Introduction/Background Ovarian cancer is one the deadliest gynaecological malignancies and many risk factors for its occurrence have been described. Despite the wealth of data on the subject, the robustness of evidence available has not yet been extensively evaluated. This review aims to fill this gap and assess the strength and validity of evidence regarding the interrelationship between various risk factors and ovarian cancer incidence and mortality.

Methodology Design: Umbrella review of systematic reviews and meta-analyses.

Data sources: PubMed, Medline, Cochrane Database of Systematic Reviews.

Eligibility criteria: Systematic reviews and meta analyses of observational studies investigating the relationship between various risks factors and ovarian cancer incidence and mortality and all- cause mortality.

Data analysis: The evidence from the meta-analyses were graded according to a statistical criteria comprised of the random effects estimate of the meta-analyses and of their largest study, the number of cases, 95% prediction intervals, I²statistic of heterogeneity between studies, excess significance bias, small studies effect and sensitivity analysis using credibility ceilings. From this, meta-analyses were classified as strong, highly suggestive, suggestive or weak evidence.

Results 205 meta-analyses from 71 eligible papers were assessed and 29 risk factors were identified. We observed strong evidence on the association between BMI as categorical variable (>30 vs. <25) and ovarian cancer incidence: RR 1.27 (1.19–1.36). For BMI as a continuous variable (per 5 unit increase), the summary effect estimate was smaller (1.27 v 1.08), and the evidence was judged as only suggestive. Between DM types 1 and 2 together and ovarian cancer incidence and mortality, the evidence was considered weak but suggestive evidence was observed for DM and all- cause ovarian cancer mortality. Additional data will be presented at the conference.

Conclusion Ovarian cancer incidence appears to be strongly associated with high BMI, while a weaker association was observed with DM.

Disclosure Nothing to disclose.