This study is the first to evaluate for differences in multiple dimensions of the symptom experience (i.e., occurrence, severity, frequency, and distress) between older and younger adults undergoing active treatment for cancer. The majority of the age differences were found in ratings of symptom occurrence with older patients reporting significantly lower occurrence rates for 15 (46.9%) of the MSAS symptoms. While fewer age-related differences were found in ratings of symptom severity, frequency, and distress, for younger and older patients who reported a specific symptom, a similar pattern was found across all three dimensions, namely when differences occurred older patients reported significantly lower ratings.
While this secondary analysis provides interesting and important data on age-related differences in various dimensions of the symptom experience in a very large sample of oncology patients, several limitations need to be acknowledged before our findings are placed within the context of an extremely limited literature. First, detailed information was not available on the exact number or specific types of comorbidities these patients experienced. In addition, specific details on the doses of CTX and RT received by these patients were not collected for these studies. Despite these limitations, findings from this initial analysis can be used to generate testable hypotheses for future research.
For almost 50% of the MSAS symptoms, older patients reported significantly lower occurrence rates. However, eight of the eleven symptoms with the highest occurrence rates were identical in the two age groups (i.e., lack of energy, pain, feeling drowsy, difficulty sleeping, dry mouth, difficulty concentrating, worrying, feeling irritable). Consistent with previous studies of multiple symptoms [15, 35–39], these eight symptoms are among the most common symptoms reported by oncology patients regardless of cancer diagnosis, stage of disease, and/or cancer treatment. Since these eight symptom occurrence rates exhibit a similar distribution pattern in both age groups, one plausible hypothesis for the significantly lower occurrence rates for six of these symptoms in older patients (no difference in lack of energy or dry mouth) is that older patients received lower doses of CTX or RT [3, 12, 14, 40]. An equally plausible hypothesis is that older patients received comparable doses of therapy. However, because of age-related changes in a number of biological processes  and/or a variety of psychosocial factors [42, 43], older patients reported lower symptom occurrence rates. For example, age-related changes may occur in the hypothalamic-adrenal-pituitary axis (HPA) that mediate the occurrence and severity of the most common cancer-related symptoms .
Another plausible hypothesis for the lower symptom occurrence rates in older patients is that older persons may experience a “response shift” in their perception of symptoms. A “response shift” is defined as an age-related psychological shift that represents a change in a person’s internal framework for the assessment of experiences . This concept was first used in oncology to describe changes over time in QOL . In the context of older patients’ reports of symptoms, these individuals may have experienced an internal reconceptualization of their symptom experience based on their lifetime experience with symptoms or their experience with symptoms from other chronic medical conditions . In addition, based on studies of barriers to pain assessment and management in older adults , older patients tend to under-report pain because: they view it as a normal part of aging; they are concerned that if they report pain it will distract their clinician from treating their cancer; they are fearful about additional diagnostic tests and their associated costs; or they are worried about additional treatments (e.g., opioid analgesics for pain) and associated adverse events [11, 48, 49]. It is plausible that these same barriers contribute to under-reporting of other symptoms in older adults. Cough and shortness of breath were among the top most frequently occurring symptoms only in the older age group. In contrast, feeling sad and sweats were unique to the younger age group. These differences in patterns of occurrence warrant investigation in future studies.
For older and younger patients who reported a specific symptom, severity ratings for the majority of the symptoms were mild to moderate. For all but six symptoms (i.e., dry mouth, feeling drowsy, feeling sad, sweats, worrying, I don’t look like myself), no age-related differences in severity scores were reported (see Table 3). In addition to the hypotheses stated above, several potential explanations for the lack of differences in symptom severity ratings warrant consideration. If younger patients received higher doses of RT and/or CTX than older patients, one would expect higher symptom severity scores in the younger group. One potential explanation for the equivalent symptom severity scores is that younger patients received more aggressive symptom management than older patients. This hypothesis is supported by studies that found that older patients receive lower doses of opioid analgesics than younger patients with comparable pain severity scores [50, 51].
In terms of the occurrence rates for specific symptoms (see Table 8), seven of the ten symptoms with the highest severity ratings were the same in both age groups (i.e., problems with sexual interest, hair loss, constipation, difficulty sleeping, swelling of arms or legs, lack of energy, pain). A similar pattern for the most severe symptoms across age groups suggests that these symptoms are common across cancer treatments. The age differential in terms of actual severity ratings may be related to dose reductions in the elderly or due to other biological or psychological mechanisms described above. Similar hypotheses could be proposed to explain the age-related differences in the symptom frequency ratings.
While a “response shift” in older persons’ perceptions of their symptoms is a plausible explanation for the lower occurrence rates for over 50% of the MSAS symptoms, one might ask why this same hypothesis does not seem to apply for the other dimensions of the symptom experience. One reason that a “response shift” may not be as evident in patients’ ratings of symptom severity, frequency, and distress is that the age group comparisons for these three dimensions were done with only patients who reported the symptom. To verify this hypothesis, differences in symptom severity scores between older and younger patients were re-analyzed with the inclusion of patients who did not report each symptom (i.e., symptom severity scores ranged from 0 to 4 instead of from 1 to 4). In these analyses, compared to younger patients, older patients reported significantly lower severity scores for: difficulty concentrating, pain, lack of energy, feeling nervous, nausea, feeling drowsy, difficulty sleeping, feeling bloated, vomiting, feeling sad, problems with sexual interest, feeling irritable, worrying, I don’t look like myself, and changes in skin. This finding suggests that in older patients who develop a symptom as a result of their cancer or its treatment, they experience it with a similar severity as younger patients. The reasons why some older patients do and do not experience cancer symptoms warrants investigation in future studies.
Besides occurrence, the largest number of age-related differences were found in the symptom distress ratings (i.e., for 43.8% of the symptoms, older patients reported significantly lower ratings). Symptom distress is defined as the degree or amount of physical or mental upset, anguish, or suffering experienced from a specific symptom [26, 52]. In one review , out of 22 studies that assessed multiple symptoms in cancer patients, only seven (31.8%) assessed distress. Of those seven, three used the MSAS . While no studies were found that evaluated for age differences in MSAS symptom distress ratings, the symptoms with the highest distress ratings in our study are comparable to those found in other studies that used the MSAS [53–55].
As shown in Table 8, six of the ten most distressing symptoms were the same in both age groups (i.e., constipation, problems with sexual interest, lack of energy, pain, difficulty sleeping, worrying). Problems with urination, difficulty swallowing, swelling of the arms or legs, and shortness of breath were among the top most distressing symptoms in the older age group. In contrast, I don’t look like myself, feeling sad, feeling bloated, and nausea were unique to the younger age group. These differences in distress patterns warrant additional research.
Of note, no age-related differences were found in symptom distress ratings for constipation and problems with sexual interest. These two symptoms which occurred in approximately 30% of the patients in both age groups warrant a careful assessment because when they do occur, they are severe, occur frequently, and are distressing not only to older patients, but to younger patients as well.
A surprising finding in this study was that a significantly higher percentage (26%) of older patients reported being fully active compared to younger patients (15.8%). While older individuals in the general population are more likely to report poorer functional status than younger individuals , the higher functional status in the older patients in this study may be attributed to lower recruitment rates among the oldest old. An alternative explanation is that younger patients received higher doses of CTX or RT that had a negative impact on their functional status.
Despite the limitations enumerated earlier in the discussion, findings from this study provide valuable information to guide clinical practice and research. As shown in Table 8, across all four symptom dimensions, the most common, severe, frequent, and distressing symptoms are similar for both age groups. What differs is the magnitude estimation for each dimension, with older persons reporting lower rates of occurrence, severity, frequency, and distress for some symptoms. Because the age-related differences in symptom severity, frequency, and distress scores were small, additional research is warranted within each age group to determine the impact of each dimension of a symptom on younger and older patients’ functional status and QOL.
The findings summarized in Table 8 provide new information on symptoms with the highest occurrence, severity, frequency and distress ratings in both age groups. This information can be used by clinicians to guide their multidimensional symptom assessments of older oncology patients. Future research needs to focus on a detailed evaluation of patient (i.e., phenotypic and genotypic characteristics) and clinical characteristics that explain the age differences in the various dimensions of the symptom experience described in this study.