Obesity and risk of ovarian cancer subtypes: evidence from the Ovarian Cancer Association Consortium

Abstract

Whilst previous studies have reported that higher body-mass index (BMI) increases a woman’s risk of developing ovarian cancer, associations for the different histological subtypes have not been well defined. As the prevalence of obesity has increased dramatically, and classification of ovarian histology has improved in the last decade, we sought to examine the association in a pooled analysis of recent studies participating in the Ovarian Cancer Association Consortium. We evaluated the association between BMI (recent, maximum, and in young adulthood) and ovarian cancer risk using original data from 15 case-control studies (13,548 cases, 17,913 controls). We combined study-specific adjusted odds ratios (ORs) using a random–effects model. We further examined the associations by histological subtype, menopausal status and post-menopausal hormone use. High BMI (all time-points) was associated with increased risk. This was most pronounced for borderline serous (recent BMI: pooled OR=1.24 per 5kg/m2; 95%CI 1.18–1.30), invasive endometrioid (1.17; 1.11–1.23) and invasive mucinous (1.19; 1.06–1.32) tumours. There was no association with serous invasive cancer overall (0.98; 0.94–1.02), but increased risks for low grade serous invasive tumours (1.13, 1.03–1.25) and in pre-menopausal women (1.11; 1.04–1.18). Among post–menopausal women, the associations did not differ between HRT users and non–users. Whilst obesity appears to increase risk of the less common histological subtypes of ovarian cancer, it does not increase risk of high grade invasive serous cancers, and reducing BMI is therefore unlikely to prevent the majority of ovarian cancer deaths. Other modifiable factors must be identified to control this disease.

Modifiable lifestyle factors and ovarian cancer incidence in women

“…Epidemiological studies [7,8] indicate a relationship between increased body weight and the risk of ovarian cancer. Pan et al [8] in their clinical-cohort study investigated the relationship between obesity and the risk of ovarian cancer.…”

Reproductive and hormone‐related risk factors for epithelial ovarian cancer by histologic pathways, invasiveness and histologic subtypes: Results from the EPIC cohort

“…1,[4][5][6][7][8][9][10][11][12][13] For example, a collaborative reanalysis of 45 epidemiologic studies found the risk reduction afforded by OC use was evident for serous, endometrioid and clear cell, but not mucinous, tumors 13 and an analysis in the Ovarian Cancer Cohort Consortium (OCAC) found a positive association between body mass index (BMI) and risk of invasive endometrioid, mucinous and clear cell, but not high grade serous, tumors. 12 However, heterogeneous associations between BMI and EOC histologic subgroups have not been observed in all studies. 14 The extent to which reproductive and hormone-related factors impact risk differentially by histologic subtype remains unclear.…”

Genetic Variants at 6p21.1 and 7p15.3 Identified by GWASs of Multiple Cancers and Ovarian Cancer Risk: a Case-control Study in Han Chinese Women

“…Several risk factors of ovarian cancer have already been identified, such as parity (Pasalich et al, 2013), never breastfeeding (Luan et al, 2013), endometriosis (Vargas-Hernandez 2013), tubal ligation (Cramer 2012), body mass index and height (BMI) (Olsen et al, 2013) and family history (Moorman et al, 2013). Furthermore, there is growing evidence suggesting that genetic variants may contribute to the susceptibility to ovarian cancer (Mohamed et al, 2013;Shen et al, 2013).…”