Diabetes mellitus and the risk of vulvar and vaginal cancer: results from a large cohort study

Abstract Background Although diabetes mellitus has been associated with increased risk of several cancers, evidence in relation to vulvar and vaginal cancers has been limited and inconsistent. We investigated the association between diabetes and the risk of vulvar and vaginal cancer risk in a nationwide cohort of 2.8 million women in Taiwan. Methods A retrospective cohort study of 2.8 million women with and without diabetes mellitus aged 18–90 years was conducted. Multivariable proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between diabetes diagnosis and the risk of vulvar and vaginal cancer. Results During 7.8 years follow-up, 553 vulvar and 506 vaginal cancer cases occurred. A history of diabetes mellitus was associated with higher risk of vulvar cancer with a HR (95% CIs) of 1.34 (1.12–1.60), but not vaginal cancer (1.09, 0.91–1.31). The HR was 1.97 (0.95–4.11) for early-onset and 1.34 (1.12–1.61) for later-onset vulvar cancer and 1.81 (0.76–4.32) for early-onset and 1.09 (0.90–1.31) for later-onset vaginal cancer. The associations were similar when restricted to type 2 diabetes cases, and when excluding the first 5 years of follow-up. Conclusion These findings suggest diabetes mellitus is associated with increased risk of vulvar, but not vaginal cancer. Further studies are needed to clarify these findings.