Body mass index and risk of cancer in young women

It is unclear how increasing body mass index (BMI) influences risk of cancer in young women. We used data from the Medical Birth, Patient and Cause of Death registers collected between 1982 and 2014 to determine the risk of obesity-related cancer types, breast cancer, all cancer and cancer-related death in relation to BMI in 1,386,725 women, aged between 18 and 45 years, in Sweden. During a median follow-up of 16.3 years (IQR 7.7-23.5), 9808 women developed cancer. The hazard ratio (HR) of endometrial and ovarian cancer increased with higher BMI from 1.08 (95% CI 0.93-1.24) and 1.08 (95% CI 0.96-1.21) among women with BMI 22.5-< 25 to 2.33 (95% CI 1.92-2.83) and 1.48 (95% CI 1.24-1.77), respectively, among women with BMI ≥ 30. There were linear and positive associations between BMI and incident cancer in the ovary, colon, endometrium, pancreas, rectum, gallbladder, esophageal cancer and renal cell carcinoma, as well as death from obesity-related cancer forms. In conclusion, we found that elevated BMI in young women linearly associated with several obesity-related cancer forms, including death from these cancers.