Obesity and survival among women with ovarian cancer: results from the Ovarian Cancer Association Consortium

Background:

Observational studies have reported a modest association between obesity and risk of ovarian cancer; however, whether it is also associated with survival and whether this association varies for the different histologic subtypes are not clear. We undertook an international collaborative analysis to assess the association between body mass index (BMI), assessed shortly before diagnosis, progression-free survival (PFS), ovarian cancer-specific survival and overall survival (OS) among women with invasive ovarian cancer.

Methods:

We used original data from 21 studies, which included 12 390 women with ovarian carcinoma. We combined study-specific adjusted hazard ratios (HRs) using random-effects models to estimate pooled HRs (pHR). We further explored associations by histologic subtype.

Results:

Overall, 6715 (54%) deaths occurred during follow-up. A significant OS disadvantage was observed for women who were obese (BMI: 30–34.9, pHR: 1.10 (95% confidence intervals (CIs): 0.99–1.23); BMI: ⩾35, pHR: 1.12 (95% CI: 1.01–1.25)). Results were similar for PFS and ovarian cancer-specific survival. In analyses stratified by histologic subtype, associations were strongest for women with low-grade serous (pHR: 1.12 per 5 kg m⁻²) and endometrioid subtypes (pHR: 1.08 per 5 kg m⁻²), and more modest for the high-grade serous (pHR: 1.04 per 5 kg m⁻²) subtype, but only the association with high-grade serous cancers was significant.

Conclusions:

Higher BMI is associated with adverse survival among the majority of women with ovarian cancer.

Obesity and ovarian cancer survival: a systematic review and meta-analysis

Studies that have examined the association between obesity and ovarian cancer survival have provided conflicting results. We reviewed and quantitatively summarized existing evidence, exploring potentially important sources of variability, such as the timing of body mass index (BMI) assessment and different cutpoints used to categorize BMI. A systematic search of MEDLINE and EMBASE was conducted to identify original data evaluating the association between obesity and survival in women with ovarian cancer. Adjusted hazard ratios (HR) from studies were pooled using a random-effects model. The meta-analysis of 14 studies showed slightly poorer survival among obese than in non-obese women [pooled HR, 1.17; 95% confidence interval (CI), 1.03-1.34]. This estimate did not vary appreciably when BMI was measured before diagnosis (1.13; 0.95-1.35), at the time of diagnosis (1.13; 0.81-1.57) or at the commencement of chemotherapy (1.12; 0.96-1.31). We found a slightly stronger association in studies that only included women with a BMI ≥ 30 in their "obese" group (1.20) than in studies that also included overweight women (BMI ≥ 25; 1.14). Women with ovarian cancer who are obese appear to have slightly worse survival than non-obese women. However, there is a large amount of inter-study variation, which means that no solid conclusions can be drawn.