The incidence of all cancers combined is currently lower in the departments of the French overseas territories than in mainland France, but is following a negative trend, likely due to the ageing of the population and the increased prevalence of risk factors linked to lifestyle (sedentary lifestyle, overweight and obesity , tobacco smoking ). Preventive measures targeting these modifiable risk factors will be key to fighting against many types of cancers.
The incidence of breast cancer is highest in developed countries, particularly in France, which, along with the countries of Northern and Western Europe, has especially high incidence . After a substantial increase up to the year 2005, the incidence of breast cancer declined sharply and then stabilized after 2008 [1, 25]. Despite a reduction observed since the middle of the 1990s, mortality remains high. Breast cancer nonetheless has a good prognosis, with net survival at 5 years of 88% for cancers diagnosed between 2005 and 2010 .
Although lower than in mainland France, the incidence of breast cancer in the French overseas territories was on the rise over the period 2008–2014. In Guadeloupe, this is reflected by a lower average age at diagnosis (56 years), with more than a third of cases occurring in women aged less than 50 , thus raising the question of the age groups targeted for organized screening.
The mean childbearing age was 30 years in Martinique and Guadeloupe, and 28 years of age in French Guiana between 2005 and 2015. During the latest 5-year period (2010–2015), a mean of 2.19 and 1.98 children per women was observed respectively for Guadeloupe and Martinique. In French Guiana, United Nations statistics report an average of 3.42 children per woman . The main risk factors for breast cancer are related to hormonal and reproductive functions (early puberty, late menopause, older age when having first child, low number of children, no breast-feeding, use of hormone replacement therapy). Other risk factors have also been identified, including alcohol consumption, obesity after menopause, low levels of physical activity, and tobacco smoking . Aging is recognized as the main risk factor for breast cancer, and the increasing age profile in both Martinique and Guadeloupe will cause steep increases in breast cancer occurrence . A systematic review examined the state of the evidence regarding the influence of social determinants of health on breast cancer risk factors in the Caribbean . The authors reported that Caribbean women with indicators of a lower socioeconomic position could be at a higher risk of breast cancer as they reported higher alcohol intake, obesity, and limited breastfeeding.
Genetic predisposition reportedly accounts for 5 to 10% of breast cancers, notably through alterations of the BRCA1 and BRCA2 genes . Improved knowledge of the variants underlying hereditary cancers and improved access to genetic testing will need to be developed in the future in the Caribbean .
Furthermore, breast cancer incidence is also impacted by screening practices. The rate of participation in organized screening, which has been implemented across all of France since 2004, was 51% in 2015–2016 for women aged 50 to 74 years, but this rate varies across Departments . Individual screening also exists, but is less well documented.
The incidence of cervical cancer is lower in developed countries that have been implementing screening using the Papanicolau smear test for many years. Together with the countries of Northern and Western Europe, France is among the countries with the lowest incidence of cervical cancer . Incidence and mortality from cervical cancer have been declining steadily since the 1980s, although the decrease has slowed somewhat since the 2000s . Net survival at 5 years for women diagnosed between 2005 and 2010 was 64% . In the French overseas territories however, cervical cancer still has a high incidence rate, particularly in French Guiana.
Cervical cancer is caused by persistent infection within the cervix with high oncogenic risk subtypes of the sexually transmitted human papillomavirus (HPV) . Active smoking, the existence of other genital infections, long-term use of oral contraceptives, and acquired immune deficiency can predispose to the persistence of infection or progression towards cancer. Epidemiological studies have been performed in the French overseas territories into the profile of HPV infections [34,35,36] and showed that it is necessary to take into account the epidemiological specificities and HPV seroprevalence observed in the French overseas territories. These studies showed epidemiological specificities in HPV genotyping. A study of 540 women with normal cervical cytology living in remote villages of French Guiana showed that 27.2% of women with normal cervical cytology had a positive HPV test. The main HPV genotypes were HPV 53(3.52%), 68(3.33%), 52(2.59%), 31(2.22%) and 16 (1.85%). This study also reported a prevalence of HPV 16 of 6.8% among HPV-infected women .
The downward trend in incidence and mortality of cervical cancer is largely explained by individual screening with smear tests since the 1960s. However, screening coverage remains suboptimal in France, and was reported to be 62% in 2010–2012 in Departments covered by an organized screening programme . The National Cancer Plan for 2014–2019 planned to expand organized screening to the whole country in 2018, and set a target participation rate of 80% . Since 2007, primary prevention of cervical cancer is possible thanks to vaccination of adolescents against high risk HPV types. The effects of vaccination on incidence and mortality will only start to appear in the medium term, firstly because of the long latency time between high-risk HPV infection and the appearance of lesions, and secondly, because of the very low vaccine coverage rate currently observed. Cervical cancer could become rare in the future if available primary and secondary prevention measures were optimally implemented.
The incidence of corpus uteri cancer is highest in developed countries. In France, compared to other European countries, the standardized incidence rate is lower than the European average . Since the 1980s, incidence has been stable, and mortality has declined slightly . Prognosis is good overall, with net survival at 5 years of 74% for cases diagnosed between 2005 and 2010 .
Endometrial cancer occurs predominantly post-menopause and is most often diagnosed based on clinical signs (metrorrhagia) when still at the localized stage. It occurs primarily as adenocarcinoma of the endometrium. The main risk factors are high endogenous (early menarche, late menopause, nulliparous women) and exogenous oestrogen levels (hormone replacement therapy that is not, or poorly compensated by progesterone, use of tamoxifen) . Metabolic risk factors also exist, notably obesity and diabetes, as well as genetic determinants (Lynch syndrome, family history in a first-degree relative). Conversely, long-term use of combined oral contraceptives, regular physical exercise and tobacco smoking are all associated with a lower risk of endometrial cancer [40, 41]. Trends in the incidence and geographical distribution of endometrial cancer could also be influenced by the prevalence of women who have undergone hysterectomy for benign indications .
Due to the fact that a large and variable proportion of death certificates do not distinguish between cervical and endometrial cancer as the cause of death, mortality rates cannot be calculated for each of these two subtypes separately at a regional level.
The incidence of ovarian cancer is higher in developed countries . In France, the standardized incidence rate is similar to the average in Eastern European countries, but lower than the average of other European countries. Incidence and mortality have been declining steadily since the 1980s [1, 43], but ovarian cancer mortality remains high, with 3590 deaths from ovarian cancer recorded each year in mainland France over the period 2007–2014, corresponding to 5.7% of cancer-related deaths in women. Net survival at 5 years was 43% for women diagnosed between 2005 and 2010 . With a very low number of cases each year, no significant differences were found for ovarian cancer for the 3 regions compared to mainland France. Nevertheless, a higher trend was observed for French Guiana for both incidence and mortality.
There are a large number of histological subtypes of ovarian cancer, and each has its own specific epidemiological, etiological and prognostic characteristics. Most often, it occurs in the form of epithelial tumours, predominantly high grade serous carcinoma. Risk factors for these tumours are mainly linked to hormonal and reproductive factors. Factors that contribute to decreasing the number of ovulation cycles during a woman’s life reportedly have a protective effect (late puberty, early menopause, parity, breastfeeding, use of oral contraception). Conversely, early menarche, late menopause and the use of hormone replacement therapy are known risk factors . Several other risk factors have also been studied including tobacco, alcohol, obesity, physical exercise, diet and exposure to asbestos or talc, with results that are sometimes conflicting, or that only show a relationship with one or more histological subtypes . A genetic predisposition is thought to account for 5 to 10% of ovarian cancers, mainly through alterations of the BRCA1 gene, and more rarely, the BRCA2 gene . The significant increase in post-cancer survival is leading many patients to cope with the after-effects of oncology treatments, which incurs a potential risk of impaired fertility. The risk of infertility in women after cancer ranges between 40 and 80% depending on their age, the type of cancer (topology, histology) and the type of treatment . Parental projects and fertility are an essential part of quality of life for patients and their families.
The main limitation of our study is the lack of data on socioeconomic status, which is not recorded in the registry. Socioeconomic inequalities in French overseas territories are more pronounced than in mainland France. Compared to the mainland, there is a lower median income, larger income inequalities, and a higher rate of unemployment in the overseas territories. At the crossroads of poor and highly developed areas, French Guiana shows a disparity in socio-economic living standards and lifestyles, linked to multiethnicity. The population benefits from the national French health insurance system, which guarantees universal access to care to all French citizens and to immigrants living legally in the country, depending on administrative and socio-economic conditions. The disparity observed in socio-economic levels in these territories could contribute to social inequalities in cancer care access.
In a recent study on PBCRs data of Martinique and Guadeloupe, the association between cancer incidence and the socioeconomic level of the residence area was analysed . A specific index of social deprivation from census data at a small area level was created, using Bayesian methods. In this study, there was no clear association between area-based deprivation and the incidence of all cancers combined. Women living in the most deprived areas had a higher incidence of stomach (Relative Risk (RR) 1.77, CI 1.12–2.89), breast (RR 1.15, CI 0.90–1.45), and cervical (RR 1.13, CI 0.63–2.01) cancers and a lower incidence of respiratory cancer (RR 0.65, CI 0.38–1.11, 47]. We found no significant association between deprivation and breast or cervical cancer incidence, with a main limitation due to the small number of cases and the consequent lack of statistical power.