The effectiveness of couple-based interventions on the marital outcomes of women with genital and breast cancer and their partners: a systematic review and meta-analysis

Background Breast cancer and genital cancer are known as cancers that affect people’s relationships with their partners. Women with such cancers are emotionally vulnerable and need more support from their partners. The present systematic review and meta-analysis evaluated the effectiveness of couple-based interventions on the marital outcomes of patients with these cancers and their intimate partners. Methods To perform this systematic review, Google Scholar and databases such as PubMed, Web of Science, Cochrane, Scopus, SID (Scientific Information Database), and Magiran were searched systematically. The reviewed studies included randomized controlled trials and quasiexperimental studies in which the intervention group, couple-based interventions, and the control group received routine care, general education or no intervention for cancer treatment. In this study, the included participants were patients with breast cancer or genital cancer and their intimate partners. The primary outcomes considered in this study included patients’ marital adjustment, patients’ marital satisfaction, patients’ marital intimacy, and patients’ marital relationships. The secondary outcomes were partners’ marital adjustment, partners’ marital satisfaction, partners’ marital intimacy, and partners’ marital relationships. A meta-analysis was performed with Review Manager v. 5.3 software (The Nordic Cochrane Centre, Cochrane Collaboration, 2014; Copenhagen, Denmark). The intervention impacts on continuous outcomes were measured using standardized mean differences (SMDs) with 95% confidence interval because of the use of various scales to evaluate the outcomes. The quality of evidence presented in the included studies was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. In the subgroup analysis, the studied outcomes were divided into two parts (theory-based and non-theory-based) in terms of the theoretical context of couple-based interventions. Results From a total of 138 retrieved studies, 14 trials were eligible for inclusion in the study. The results of the meta-analysis showed that the patient’s marital satisfaction increased significantly with couple-based interventions (SMD 0.46, 95% confidence interval 0.07 to 0.85; 7 trials, 341 patients, very low certainty) compared to the control group, but the evidence was uncertain. However, there were no significant differences between the groups in the partner’s marital satisfaction, the patient’s and partner’s marital adjustment, and the patient’s and partner’s marital intimacy. Additionally, the results of the subgroup analysis showed that the couple-based interventions significantly increased the patient’s marital adjustment (SMD 1.96, 95% CI 0.87 to 3.06; 4 trials, 355 patients, very low certainty), the partner’s marital adjustment (SMD 0.53, 95% CI 0.20 to 0.86; 4 trials, 347 partners, very low certainty), the patient’s marital satisfaction (SMD 0.89, 95% CI 0.35 to 1.43; 2 trials, 123 patients, very low certainty), and the partner’s marital satisfaction (SMD 0.57, 95% CI 0.20 to 0.94; 2 trials, 123 partners, very low certainty) compared to the control group in theory-based studies. In. However, in non-theory-based studies, the results of the meta-analysis revealed no significant differences between the intervention and control groups. Conclusions The results of this study demonstrated the impact of couple-based interventions on the marital outcomes of patients with breast and genital cancers. Because of the very low confidence in the evidence, high-quality randomized trials with a sufficient sample size should be conducted considering the proper theoretical context. Supplementary Information The online version contains supplementary material available at 10.1186/s12885-024-12088-x.

The effectiveness of couple-based interventions on the marital outcomes of women with genital and breast cancer and their partners: a systematic review and meta-analysis Introduction Breast, uterine, cervical, and ovarian cancers are the most common cancers among women.Breast cancer is highly prevalent in developing and developed countries and accounts for nearly one-third of newly diagnosed cancers in women [1].With nearly 2.26 million new cases in 2020, breast cancer was identified as the most common women's cancer worldwide, which includes 12.5% of all cancers in women [2].In addition to breast cancer, genital cancer is extensively prevalent among women [3].In 2020, the incidence rate of genital cancers around the world was reported by more than 1.3 million women, 7.29% of whom comprise new cancer cases worldwide [4].
Despite the increasing incidence of cancer, the enhancement of diagnostic and treatment methods has increased the cancer survival rate and the number of affected women, which has affected various people through the long-term diagnostic and treatment of cancer [5]; these findings further clarify the need to focus on patients' quality of life.Breast and genital cancers lead to broad changes in the personal and marital lives of infected women [6].The results of a recent study indicated that patients with women-specific cancers experience multiple unfavorable situations, including lowering intimacy with their partners and trying to maintain their sexual exclusivity.Women with breast cancer suffer from problems such as decreased self-esteem, a decreased sense of femininity, weakness in sexual relations, and poor body image because of mastectomy, which disturbs their marital life [7].This cancer not only creates a severe mental burden for patients but also for their life partners [8].According to the results of a systematic review, the husbands and male partners of women who suffer from breast cancer experience profound and considerable changes in terms of family life and feelings [9].Studies indicate that marital problems caused by cancer treatment are common and distressing consequences for individuals with genital and breast cancer.This can lead to changes in their intimate relationships with their partners [10,11].This not only affects cancer patients but also their partners in terms of the quality of marital life [12].
Many women are hesitate of talking about their sexual problems, and on the one hand, nurses and doctors disregard this issue; thus, these women deal with this problem alone [11].Indeed, women with cancer and their partners need considerable intervention to resolve a variety of sexual and marital problems induced by cancer treatment [13].Considering the psychosocial adaptability and ability of partners to communicate effectively and cope together, there is wide interest in couple-based interventions in cancer care [14].A couple-based intervention systematically involves the intimate partner and focuses on the couple as a unit.This type of intervention can be beneficial for both patients and their partners who are dealing with cancer and related sexual problems [15].
Research shows that intimate partners can considerably protect and support women with cancer during the treatment and recovery process [16,17].Adopting a couplecentered process may not only decrease negative cancer outcomes for both simultaneously but also support their mental growth and mutual flexibility [18].
Couple-based interventions (including both patients and their intimate partners) [19] can be more advantageous for couples [15] than can those with patients only and couple-based coaching interventions (intimate partners help the patients as assistants or coaches) [20].Such interventions have long-term effects on maintaining behavioral changes and reducing the concerns of intimate partners during daily care activities to support patients [21,22].To date, multiple studies have been conducted on couple-based interventions, but some research has shown contradictory results.For example, Zhang et al. [23] reported a considerable effect of couple-based interventions on marital satisfaction, while Price-Blackshear et al. [24] claimed the opposite result and was even harmful.Additionally, Comez et al. [25] and Li et al. [6] showed the positive effect of couple-based interventions on marital adjustment, whereas Fergus et al. [19] observed no effect of the intervention on marital adjustment.Therefore, systematic reviews seem to be required to analyze the effects of such interventions.
While several systematic reviews have been conducted on couple-based interventions among cancer patients [15,26,27], the participants in these review studies were not those with women-specific cancer patients, and the intimate partners of the patients were not included in the examination.Additionally, different outcomes have been investigated.Therefore, to address these gaps and since breast and genital cancers have a similar nature and affect women's femininity and often have unique psychological, emotional, and social implications for women, including impacts on body image and sexuality, this systematic review and meta-analysis studies the effects of couplebased interventions on marital outcomes, including marital adjustment, marital satisfaction, and marital intimacy, on couples with breast and genital cancer (women) and intimate partners.

Methodology
This systematic review is based on the Cochrane Handbook for Systematic Reviews, and the results are reported according to PRISMA; it is registered on PROSPERO (Registration number: CRD42023453336).

Search strategy
Systematic searches of databases, including PubMed, Scopus, Web of Science, Cochrane Library، SID (Scientific Information Database), and Magiran, were performed beginning on 30th April 2023 with related keywords to obtain published studies in English and Persian; the search was completed on 5th June 2023 without any date limits.The complete search strategy for each database is presented in Appendix 1.Additionally, the references used in these studies were manually searched to identify additional associated studies not registered by the electronic search.This search was performed in two steps, once at the beginning and exactly before the end (final search) of the study.There were no differences between the studies included in both periods.

Inclusion and exclusion criteria
All randomized controlled and quasi-experimental trials in English and Persian that investigated the effectiveness of couple-based interventions in patients with breast and genital cancers and their intimate partners to improve marital outcomes were included in this study.The exclusion criteria were abstracts from conferences, study protocols, and studies without related data.

Participants
Women with breast and genital cancers and their intimate partners were included in this study.

The type of interventions
The interventions included any type of couple-based interventions with the involvement of patients with breast and genital cancers and their intimate partners.The control group received no intervention or received routine care or general education.

Study outcomes
The primary outcomes of this study included the patient's marital satisfaction, the patient's marital adjustment, the patient's marital intimacy, and the patient's marital relationship.Secondary outcomes included the partner's marital satisfaction, the partner's marital adjustment, the partner's marital intimacy, and the partner's marital relationship.

Study selection
EndNote software was used to manage the studies (Clarivate, Thomson Reuters, Philadelphia, Pennsylvania).After removing duplicate cases, two authors, H.Z. and Z.A-D., separately investigated the titles and abstracts of the extracted articles in terms of the inclusion and exclusion criteria, followed by evaluating the full texts of the papers.Any disagreement about the eligibility of the studies was resolved through discussion; otherwise, it was consulted by a third author (M.H.). Figure 1 shows the study flow, the number of identified/excluded studies, and the number of included studies.

Data extraction and management
To extract data, two authors (H.Z & Z. A-D) extracted the study characteristics independently using a dataextraction form based on the Cochrane Handbook [28].Any disagreements were resolved through discussion.The extracted data included the first author's name, country, year of publication, study design, study groups, type of intervention, type of blinding, follow-up period, number of participants in each group, participants' health status, primary outcomes, secondary outcomes, results, and theoretical contexts.

Risk of bias assessment in the included studies
Two authors (H.Z & Z. A-D) independently investigated the risk of bias in all included studies using the criteria listed in the Cochrane Handbook.To evaluate the risk of bias in this study, the included randomized controlled trials were investigated by the ROB-1 approach [29] in terms of random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessors, selective reporting, and incomplete outcome data.In addition, the included semiexperimental trials were reviewed using the ROBINS-1 approach [30].Then, the judgments were adapted to each other, and any disagreement was resolved by consulting the third author (M.H.).

The quality assessment of a control set using the GRADE approach
The quality of evidence in the included studies (related to the research outcomes) was evaluated by the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach, which includes five dimensions: risk of bias, imprecision, inconsistency, indirectness, and publication bias [31].This evaluation was independently performed by two authors (H.Z.& Z.A-D.), and any disagreements between the two authors were resolved through discussion with a third author (M.H.).To explore the presence of clinical heterogeneity, all the trials included in the study were described and compared in terms of the studied population's characteristics and those of interventions offered to the studied groups.The presence of statistical heterogeneity was assessed using the I 2 statistic and a confidence interval of 95%.In cases with I 2 ≥ 25%, the certainty of evidence was reduced due to contradictions [32].To evaluate the indirectness, the study population, type of intervention, control group, and study outcomes were examined in terms of response to the current systematic review [33].To evaluate the imprecision, the trials were assessed in terms of sufficient participants to calculate the estimation effect and confidence interval around this effect [34].To compute the quality of evidence for each studied outcome, the quality of evidence was reduced to one and two degrees if there were severe and very severe concerns, respectively.

Measures of treatment effect
Data on marital satisfaction, marital adjustment, and marital intimacy were extracted from the patients and intimate partners for the control and intervention groups.To calculate the impacts of the interventions on the continuously studied outcomes of the trials, the mean difference and standard deviation before and after the intervention were first obtained for the intervention and control groups.In addition, a standardized mean difference (SMD) (with a 95% confidence interval) was used to report outcomes using different scales to examine continuous outcomes [35].

Data analysis
The data were analyzed to compare the study outcomes between the intervention and control groups in cases with at least two trials with Review Manager 5.3 software.In the case of high heterogeneity between the studies (I 2 ≥ 25%), the random effect method was used rather than the fixed effect method to calculate the size of the intervention impact on the outcome of interest.Regarding the studies the control group did not receive routine care or no intervention, we excluded those studies and did a meta-analysis again.In the subgroup analysis, the studies were divided into two parts (theory-based and non-theory-based) in terms of the theoretical context.The theories used in the included studies are the Roy adaptation model, the systemic transactional model of stress and coping, the PLISSIT model, attachment behavior and attachment style, theories of behavioral couples, and the preliminary live with love conceptual framework.

Description of the studies
The results of the search strategy for the studies are summarized in the PRISMA diagram (Fig. 1).From a total of 138 retrieved studies in the searching process, 113 studies were screened and excluded because they did not meet the inclusion criteria for this study.Finally, 14 trials out of 25 reviewed studies were included in the final analysis based on the research target and inclusion criteria (Table 1), with 11 excluded studies (Table 2).

Characteristics of included studies
The characteristics of the trials included in the systematic review, including the first author's name, country, year of publication, study design, study groups, type of intervention, type of blinding, follow-up period, number of participants in each group, participants' health status, main outcomes, secondary outcomes, results, and theoretical contexts, are summarized in Table 1.
The 14 studies comprised randomized controlled trials (RCTs, n = 6), multicenter RCTs (n = 2), pilot RCTs (n = 2), and quasi-experimental (n = 4).These studies concentrated on women with breast and genital cancers and their intimate partners.The sample volume (couples included in the study) was 2192 participants (628 and 468 subjects in the intervention and control groups, respectively).These studies were performed in the USA (n = 5) and China (n = 2), as well as in Greece, Canada, Denmark, Turkey, Iceland, South Korea, and Iran, each with one study.Additionally, nine out of the 14 included studies contained a theoretical context for the intervention.The studies were published in English from 1983 to 2023, except for one study published in Persian.

Characteristics of couple-based interventions
In all 14 trials included, couple-based interventions were provided as an intervention along with routine care during cancer treatment, and the control group received routine care, general education or no intervention.In the intervention conditions of these trials, couple-based interventions were provided by trained nurses, clinical psychologists, therapists, advisers, and mental health professionals to women with breast and genital cancers and their intimate partners.The intervention duration ranged from 4 weeks to 4 months, and the intervention was carried out in 3-8 sessions.The number of participants in each educational session ranged between 8 and 82, and the duration of each session ranged from 45 to 120 min.The frequency of sessions was different between once and twice a week or once a month.These interventions were implemented as face-to-face, educational videos, telephone advice through a website, and the sending of educational articles on an Internet platform.The provided educational content included enhancing relationships, adjuvant treatment, postoperative recovery, promoting a sense of control and the patient's/life partner's dominance, breast cancer and treating methods, preventing and managing treatment-related symptoms, arm and shoulder exercises, pregnancy, therapeutic conversation based on couples' strengths, mental education, skill training, consultation, knowing and dealing with family and marital problems, enhancing relationship skills, and learning problem solving related to intimate relationships.In the trials included in this study, the control group received routine care in seven studies [23,25,[36][37][38][39][40].Three studies contained no intervention control group [17,19,41].In one study, a control group received individualized training [24].In another study, the control group received general education about diet and exercise [6].Two other studies did not explicitly report the intervention type received by the control group [42,43].

Health status of participants
The participants included in this systematic review were women with breast and genital cancers and their intimate partners.The participants provided informed consent to participate in the trials, and the descriptions of the articles indicated the participants' consent for randomization.In a study by Hedayati et al. [41], the "marital intimacy" outcome was reported for couples but not for a patient and the intimate partner separately.The first author was asked for the expected consequence of a patient and partner separately, but no response was received.In a study by Kalaitzi, the "marital satisfaction" outcome was only reported for the patient, not for the intimate partner [43].

Risk of bias in the included studies
The evaluation of the quality of the RCTs included in this study is reported in Figs. 2 and 3.All RCTs included in the study were rated as low risk in terms of random sequence generation, except for three cases as an unknown risk [24,42,43].In terms of allocation concealment, however, only three studies were rated as low risk [6,23,39], and the remaining studies were rated as high risk or unknown.Based on the nature of the study, i.e., couple-based interventions, blinding the participants and personnel was difficult.Therefore, the participants of the study were only blinded in one study where both the couples and the assessor were blinded to the intervention [37].The outcome assessors were blinded only in three studies [23,36,39], and the remaining were at a high risk.
In terms of incomplete outcome data or attrition bias, all studies were rated as low risk, and only three studies were rated as unknown risk [36,42,43].In terms of selective reporting bias, all studies were rated as low risk, and only one study was rated as high risk [39] (see Table 3; Figs. 2 and 3).
The overall risk of bias in quasi-experimental trials was considered serious due to at least a serious bias in the study subdomains.In terms of bias due to confounding, two studies were at moderate risk [25,38], one study was at serious risk [41], and one study was at low risk [17].In terms of bias in the selection of participants, except for one low-risk study [17], the other included studies were at serious [25,41] or moderate [38] risk.In terms of bias in the classification of interventions, only one study was rated at moderate risk [41], and the others were rated at low risk.In terms of bias due to deviations from intended interventions, all the studies were considered low risk.Regarding bias due to missing data, two studies were at low risk [17,25], one study was at moderate risk [38], Bultz et al. 2000 [54] Lewis et al.2019 [20] Razavi et al.2000 [55] Participants in the educational intervention were only partners Shahed et al.2016 [56] Participants in the educational intervention were only patients Differences in methodology Naghiyaee et al. 2014 [57] Single-case experimental design Harb et al.2022 [58] A Mixed-Methods Integrative Study Manne et al.2004 [59] Correlational study Weakness in clarity of outcomes Scott et al.2004 [60] The sexual adjustment scale is not clearly stated.No study Data Suzuki et al.2020 [61] Lack of access to the full text of the article Zimmermann et al.2016 [62] Lack of access to the full text of the article The language of the article Nho et al.2013 [63] Writing an article in Korean Fig. 2 Risk of bias graph.Review authors' judgments about each risk of bias item presented as percentages across all included studies and one study was at no information [41].All the studies were at serious risk because of bias in the measurement of outcomes.In terms of bias in the selection of reported results, all studies were at moderate risk.In summary, all the quasi-experimental trials included in this study were at serious risk of bias (Table 4).

Marital adjustment of patients
Seven RCTs [6,19,24,37,39,40,42] and one quasiexperimental trial [25] compared patients' marital adjustment in two groups: intervention (receiving couple-based education) and control (receiving routine care or general education or waitlist).Three studies used the Revised Dyadic Adjustment Scale (RDAS) [6,19,39], one study utilized the Locke-Wallace Marital Adjustment Test (MAT) [42], one study employed the Dyadic Adjustment Scale [24], one study applied the Dyadic Adjustment Scale (DAS-7) [40], and another used the PAL-C Scale [37].The results of two studies showed that providing couple-based interventions for couples could positively affect the marital adjustment of patients compared to the control group [6,39].On the other hand, two studies indicated the opposite result, that is, a partial decrease in patients' marital adjustment [24,40].In two other studies, couple-based interventions had no effect on patients' marital adjustment [19,42].All these studies were included in the meta-analysis, except for one study by Budin et al., who separately evaluated emotional, physical, and social compatibility in patients with breast cancer and their partners [37].The results from seven studies conducted on 519 patients indicated that couplebased interventions did not affect marital adjustment compared to routine care, but the evidence is uncertain (Fig. 4) (SMD 0.27, 95% CI -0.12 to 0.66; 7 trials, 519 patients, very low certainty).The result of meta-analysis with excluding studies that the control group received general education showed that there was no change in the significance (SMD 0.33, 95% CI -0.34 to 0.51; 5 trials, 344 patients, very low certainty).The subgroup analysis results showed that theory-based couple-based interventions significantly increased patients; marital adjustment compared to the control group (SMD 0.5, 95% CI 0.05 to 0.95; 4 trials, 355 patients, very low certainty).In contrast, non-theory-based interventions did not significantly influence the patients' marital adjustment compared to the control group (SMD − 0.12, 95% CI -0.48 to 0.25; 3 trials, 164 patients, very low certainty).

Marital satisfaction of patients
Seven RCTs [19,23,24,36,40,42,43]  Scale [43].Studies showed that couple-based interventions could improve the marital satisfaction of patients [43] compared to the control group [23,36,40,42].However, the results of one study revealed no change in the patient's marital satisfaction [19], and another study indicated the opposite effect [24].All these studies were included in the meta-analysis.The results of seven studies conducted on 341 couples indicated that providing couple-based interventions with routine care might increase patients' marital satisfaction compared to the control group, but the evidence is uncertain (Fig. 5) (SMD 0.46, 95% CI 0.07 to 0.85; 7 trials, 341 patients, very low certainty).The result of the meta-analysis with excluding studies that the control group received general education showed that there was no change in the significance (SMD 0.59, 95% CI 0.33 to 0.85; 6 trials, 264 patients, very low certainty).Additionally, the subgroup analysis results showed that theory-based couple-based interventions significantly increased patients' marital satisfaction compared to the control group (SMD 0.89, 95% CI 0.35 to 1.43; 2 trials, 123 patients, very low certainty).In contrast, nontheory-based couple-based interventions did not significantly influence patients' marital satisfaction compared to the control group (SMD 0.22, 95% CI -0.16 to 0.59; 5 trials, 218 patients, very low certainty).

Marital intimacy of patients
One RCT [40] and three quasi-experimental trials [17,38,41] compared the patients' marital intimacy in the intervention (receiving couple-based intervention) and control (receiving routine care) groups.To evaluate marital intimacy, Reese et al. used the PAIR questionnaire [40], Jonsdottir et al. utilized the Ice-Beliefs questionnaire [17], Nho et al. employed the Marital Intimacy questionnaire [38], and Hedayati et al. applied the Marital Intimacy Questionnaire Bagarozzi [41].The results of two studies showed that couple-based interventions significantly increased the marital intimacy of patients [17,41].On the other hand, Reese et al. reported no significant changes in women's marital intimacy despite providing couple-based interventions [40].Although Hedayati et al. reported marital intimacy based on couples but not separately by patients and intimate partners.Additionally, Jonsdottir et al. did not report the results of the control and intervention groups separately.This means that the data of both the control and intervention groups were reported as integrated.Thus, this study was not included in the meta-analysis.A meta-analysis of data from two trials of 71 patients indicated that couple-based Table 4 Risk of bias of included studies (Semi-experimental study) interventions did not affect the marital intimacy of patients compared to that of routine care, but the evidence is uncertain (Fig. 6) (SMD 0.20, 95% CI -0.27 to 0.68; 2 trials, 71 patients, very low certainty).

Marital relationship of patients
No studies were found regarding the effect of couplebased interventions on marital relationships.

Marital adjustment of partner
Seven RCTs [6,19,24,37,39,40,42] and one quasiexperimental trial [25] compared the marital adjustment of intimate partners in both intervention (receiving couple-based education) and control (receiving routine care or general education or waitlist) groups.Three studies used the Revised Dyadic Adjustment Scale (RDAS) [6,19,39], one used the Locke-Wallace Marital Adjustment Test (MAT) [42], one study employed the Dyadic Adjustment Scale [24], one research applied the Dyadic Adjustment Scale (DAS-7) [40], and Budin et al. used the PAL-C [37].The results of two studies revealed a positive and significant effect of couple-based interventions on the marital adjustment of intimate partners compared with the control group [6,39].Additionally, one study reported no change in the marital adjustment of intimate partners [24], and another reported a partial increase [40].In two other studies, couple-based interventions did not affect the marital adjustment of intimate partners [19,42].All the studies were included in the meta-analysis, except for one study evaluating various outcomes [37].Data obtained from seven studies performed on 509 partners showed that marital adjustment of partners was not influenced by couple-based interventions compared to routine care (Fig. 7) (SMD 0.29, 95% CI -0.06 to 0.65; 7 trials, 509 partners, very low certainty.(The result of

Marital satisfaction of partners
Six RCTs [19,23,24,36,40,42] compared the marital satisfaction of intervention groups (receiving couplebased education) with control groups (receiving routine care or general education or a waitlist) in intimate partners of patients.To evaluate marital satisfaction, Fergus et al. used the Kansas Marital Satisfaction Survey [19], Zhang et al. utilized the Olson Marital Quality Questionnaire [23], two studies employed the QMI [24,36], Reese et al. applied the PROMIS SexFS [40], Christensen et al. used the SSS [42], and Kalaitzi et al. utilized a sexuality and body image tool [43].The results of most studies showed that couple-based interventions improved the marital satisfaction of partners compared to the control group [23,36,40,42].However, the results of one study indicated no changes in the marital satisfaction of partners [19], and the opposite effect was observed in another study [24].All these studies were included in the metaanalysis.Data obtained from six studies performed on 299 partners disclosed that the coupled-based intervention could not affect marital satisfaction compared with the control group, but the evidence is uncertain (Fig. 8) (SMD 0.22, 95% CI -0.10 to 0.54; 6 trials, 299 patients, very low certainty).The result of meta-analysis with excluding studies that the control group received general education showed that there was no change in the significance of the result (SMD 0.32, 95% CI -0.01 to 0.66; 5 trials, 224 patients, very low certainty).

Marital intimacy of partners
One RCT [40] and three quasi-experimental trials [17,38,41] [41].The results of two studies showed that couple-based interventions led to a significant increase in marital intimacy between couples [17,41].In a study by Nho et al., marital intimacy significantly increased between intimate partners [38].Although Hedayati et al. reported marital intimacy based on couples, they did not report it separately by patients and intimate partners.Additionally, Jonsdottir et al. reported the results of control and intervention groups with each other, thus these two studies were not included in the meta-analysis.A meta-analysis applied to data from two trials performed on 71 patients indicated that couple-based interventions had no effect on the marital intimacy of partners compared to routine care, but the evidence is uncertain (Fig. 9) )SMD 0.06, 95% CI -0.76 to 0.89; 2 trials, 71 patients, very low certainty).
According to the quality or certainty of evidence evaluated using the GRADE approach, the quality of evidence decreased by three degrees and reached a very low certainty in marital adjustment outcomes of patients and partners and patients' marital satisfaction due to the serious concern about evaluating the risk of bias and inconsistency in the included studies.In the marital intimacy outcome of patients, the quality of evidence was reduced by three degrees and reached very low certainty due to the serious concern about evaluating the risk of bias and imprecision in the included studies.In the marital satisfaction outcome of the partner and marital intimacy of the partner, the quality of evidence was reduced by three degrees and reached very low certainty due to the severe concern about evaluating the risk of bias, inconsistency, and imprecision (Table 5).

Marital relationship of partners
No studies were found regarding the effect of couplebased interventions on marital relationships.

Discussion
The results of this systematic review of 10 RCTs and four quasi-experimental trials demonstrated that, compared with no intervention, couple-based interventions might increase patients' marital satisfaction (providing routine care, general education or no intervention); however, the evidence is uncertain.However, there were no significant differences between the groups in outcomes such as the marital satisfaction of partners, marital adjustment, and marital intimacy between patients and partners.On the other hand, the results of the subgroup analysis showed that the marital satisfaction and marital adjustment of patients and partners increased significantly compared to the control group in studies that used couple-based interventions with a theoretical basis or conceptual framework for the intervention.In contrast, no significant difference between the intervention and control groups was observed in the studies that did not follow a specific conceptual framework.
Regarding the outcome of marital satisfaction, Wang et al. performed a systematic review of 12 RCTs to evaluate the effectiveness of couple-based interventions in the health-related quality of life (including marital satisfaction and depression and anxiety) in patients with cancer and their spouses.The results of the study showed that couple-based interventions significantly improved marital satisfaction and reduced depression and anxiety in the patients and their spouses.The result of this study is in line with those of the current study [44].Li et al. conducted a systematic review of couple-based interventions on couples coping with cancer by including 12 RCTs and five cohort studies.In their study, the patients suffered from any kind of cancer, including prostate, breast, and digestive cancers.The results showed improvements in marital satisfaction and sexual performance in the patients and their partners, which corresponds to the findings of the current study [45].However, only one of the included studies in these two systematic reviews was specific to the outcome of marital satisfaction in breast cancer patients, and the remaining studies were related to different types of cancer.Considering that breast and genital cancer, which affect femininity, can have a greater impact on marital satisfaction [46,47], On the other hand, marital satisfaction is an issue related to couples, which highlights the importance of couple interventions in this type of cancer patients and their intimate partners.
Regarding our findings about subgroup analysis and theory-based intervention, the results of a systematic review showed that a web-based training program based on Roy's theory improved couples' marital adjustment.This finding shows the importance of using theory in interventions [48].To fully realize the potential of health services research in enhancing healthcare delivery, it is recommended that institutions and researchers prioritize the integration of theory [49].Studies indicate that incorporating theory as the foundation for interventions leads to greater changes in health behaviors compared to interventions without a theoretical basis [50].Couple-based interventions, which are rooted in theory and conceptual frameworks, offer a structured approach to address the unique needs of couples [51].Li et al. 's study emphasizes the significance of developing a conceptual framework for couple-based interventions in cancer patients and their intimate partners.This study combines the theories used in the included studies and presents a preliminary Live With Love Conceptual Framework (P-LLCF) theory for cancer couples [52].In another study by Manne et al., the authors emphasized the importance of using theory in the interventions of couples facing cancer.In this study, resource theories such as cognitive-social processing theory explained how marital relationships can provide support for both patients and partners during challenging life events such as cancer [53].It seems that by utilizing theory, interventions can target specific aspects of the couple's relationship, communication patterns, coping strategies, and emotional expression, thereby increasing the likelihood of improving marital outcomes.
In our study, we found a nonsignificant difference in marital intimacy outcome, possibly because of the low number of included studies and patients.This can be described by the very small sample volume of the included studies to determine the effectiveness of the intervention.On the other hand, Hedayati et al. 's study reported the positive effect of a couple-based intervention on couples' marital intimacy.However, considering that the results were reported for the couple (not for the patient and partner separately), it was not included in the meta-analysis [41].Therefore, it seems that more intervention studies are needed in this regard to help the findings of the current study.
Overall, experiencing a cancer diagnosis and undergoing treatment can significantly impact not only the individuals directly affected but also their intimate partners.Cancer can strain even the strongest relationships, leading to increased conflict, decreased intimacy, and reduced satisfaction.Considering the significant impact that a cancer diagnosis and treatment can have on both individuals and their intimate partners, it is crucial to consider couple-based interventions.These findings may indicate that implementing couple-based interventions is more needed in patients with breast and genital cancers than in those with other types of cancer.

Strengths and limitations
The strengths of the current study are the use of the Cochrane Handbook for the Systematic Review of Trials and the study registration in PROSPERO.The studies were searched in two steps, at the beginning and before the end of the study, and no limitations were applied to the publication dates of the studies.Additionally, almost all the studies mentioned the outcomes of partners, except for one study that focused only on the outcomes of patients.Regarding the limitations of this study, the included studies were limited to the English and Persian languages.In addition, only three studies were performed on patients with genital cancer and their intimate partners, and the rest were related to breast cancer.Therefore, additional studies should be conducted in this context to help confirm the findings of the present study.Additionally, the conclusion was limited due to the very low-certainty evidence.

Conclusion
According to the meta-analysis results, couple-based interventions according to the theoretical context are effective at improving the marital outcomes of patients with breast and genital cancers and their partners, but the evidence is uncertain.The results of this systematic review indicate that few studies are available about the effect of couple-based interventions on some outcomes, such as marital intimacy.Therefore, high-quality RCTs and sufficient sample volumes should be carried out based on the CONSORT statement and a useful theoretical context to clarify the impact of couple-based education on these outcomes.Additionally, couple-based interventions for male cancer patients and their intimate partners are recommended for further studies.

Fig. 1
Fig. 1 Flow diagram of the systematic review process compared patients' marital satisfaction in both the intervention (receiving couple-based interventions) and control (receiving routine care or general education or waitlist) groups.To evaluate marital satisfaction, Fergus et al. used the Kansas Marital Satisfaction Survey [19], Zhang et al. utilized the Olson Marital Quality Questionnaire [23], two studies employed the Quality of Marriage Index (QMI) [24, 36], Reese et al. applied the PROMIS SexFS [40], Christensen et al. used the Sexual Satisfaction Scale (SSS) [42], and Kalaitzi et al. utilized the Sexuality and Body Image

Fig. 3
Fig. 3 Risk of bias summary: Review authors' judgments about each risk of bias item for each included study

Fig. 5
Fig. 5 Couple-based intervention group versus control group, Outcome 2: Marital satisfaction of patients

Fig. 7 Fig. 6
Fig. 7 Couple-based intervention group versus control group, Outcome 4: Marital adjustment of partners

Fig. 9
Fig. 9 Couple-based intervention group versus control group, Outcome 6: Marital Intimacy of partners

Table 1
Characteristics of excluded trials Author (s) Location/ (

Table 1 (
continued) a Randomized Controlled TrialTable 1 (continued) compared marital intimacy in intimate partners of patients in both intervention (receiving couple-based education) and control (receiving routine care) groups.To evaluate marital intimacy, Reese et al. used the PAIR questionnaire [40], Jonsdottir et al. utilized the Ice-Beliefs Questionnaire [17], Nho et al. employed the Marital Intimacy Tool [38], and Hedayati et al. applied the Marital Intimacy Questionnaire Bagarozzi