Risk of female-specific cancers according to obesity and menopausal status in 2.7 million Korean women: Similar trends between Korean and Western women

Abstract

Background: Studies examining the relationship between obesity and female-specific cancers have been mainly conducted in Western populations. We aimed to investigate the risk of female-specific cancers according to obesity and menopausal status using a nationwide cohort in Korea. Methods: We identified 2,708,938 women from the National Health Insurance Service cohort, and obtained baseline body mass index (BMI), waist circumference (WC), and other healthcare data, measured and collected during a health examinations and cancer-screening survey. By setting a normal weight/WC group (BMI, 18.5-22.9 kg/m(2) or WC, 80.0-84.9 cm) as the reference, we conducted multivariate analyses using the Cox proportional hazard model to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (95% CIs) for each cancer. Findings: The total follow-up duration was 22389854.63 person-years. In post-menopausal women, the risk of breast, endometrial, and ovarian cancers significantly increased as the BMI classification level increased from normal to class II obesity (aHRs [95% CIs], 1.49 [1.38-1.61], 2.11 [1.81-2.46], and 1.38 [1.20-1.58], respectively). The risk of breast and endometrial cancers also increased as the WC classification increased from < 75.0 to >= 95.0 cm. With a WC of 80.0-84.9 cm as the reference, the lowest risk of breast and endometrial cancers was observed in WC < 75.0 cm (aHRs [95% CIs], 0.85 [0.81-0.89] and 0.75 [0.67-0.84], respectively) while the highest risk was observed in WC >= 95.0 cm (aHRs [95% CIs], 1.19 [1.10-1.29] and 1.56 [1.33-1.82], respectively). In pre-menopausal women, the risk of breast cancer significantly decreased in those with class I and II obesity compared to those with normal BMI (aHRs [95% CIs], 0.96 [0.92-0.999] and 0.89 [0.81-0.97], respectively), whereas the trends of endometrial and ovarian cancer incidence in pre-menopausal women were similar to those observed in post-menopausal women. For cervical cancer, only class II obesity was significantly associated with increased risks in both post-menopausal and pre-menopausal women (aHRs [95% CIs], 1.18 [1.01-1.39] and 1.27 [1.02-1.57], respectively). Interpretation: In this large population-based cohort study in Korean women, we observed that the impact of obesity on the development of female-specific cancers differs according to the malignancy type and menopausal status. Similar trends were observed between Korean and Western women. (C) 2021 Published by Elsevier Ltd.