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/m² 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.

Funding: The Korea Health Industry Development Institute (no. HI16C2037).

Keywords: Body mass index; Breast cancer; Cervical cancer; Endometrial cancer; Incidence; Menopause; Obesity; Ovarian cancer; Waist circumference.

Fig. 1

Flow diagram of the study population selection.

Fig. 2

Association of body mass index and incidence of female-specific cancers among all women, pre-menopausal women, and post-menopausal women: (A) breast cancer, (B) endometrial cancer, (C) ovarian cancer, and (D) cervical cancer. In the total women, age, smoking status, alcohol consumption, physical activity, diabetes, parity, menopausal status, and age at menarche were adjusted. In the pre-menopausal women, age, smoking status, alcohol consumption, physical activity, diabetes, parity, and age of menarche. In the post-menopausal women, age, smoking status, alcohol consumption, physical activity, diabetes, parity, age of menarche, and hormonal replacement therapy duration were adjusted. *Reference.

Fig. 3

Association of waist circumference and incidence of female-specific cancers among all women, pre-menopausal women, and post-menopausal women: (A) breast cancer, (B) endometrial cancer, (C) ovarian cancer, and (D) cervical cancer. In the total women, age, smoking status, alcohol consumption, physical activity, diabetes, parity, menopausal status, and age at menarche were adjusted. In the pre-menopausal women, age, smoking status, alcohol consumption, physical activity, diabetes, parity, and age of menarche. In the post-menopausal women, age, smoking status, alcohol consumption, physical activity, diabetes, parity, age of menarche, and hormonal replacement therapy duration were adjusted. *Reference.

Fig. 4

Summary of relationships between combinations of general and abdominal obesity and risks of female-specific cancers. In the total women, age, smoking status, alcohol consumption, physical activity, diabetes, parity, menopausal status, and age at menarche were adjusted. In the pre-menopausal women, age, smoking status, alcohol consumption, physical activity, diabetes, parity, and age of menarche. In the post-menopausal women, age, smoking status, alcohol consumption, physical activity, diabetes, parity, age of menarche, and hormonal replacement therapy duration were adjusted.

Fig. 5

Risk of female-specific cancers according to the combination of general and abdominal obesity among all women, pre-menopausal women, and post-menopausal women: (A) breast cancer, (B) endometrial cancer, (C) ovarian cancer, and (D) cervical cancer. In the total women, age, smoking status, alcohol consumption, physical activity, diabetes, parity, menopausal status, and age at menarche were adjusted. In the pre-menopausal women, age, smoking status, alcohol consumption, physical activity, diabetes, parity, and age of menarche. In the post-menopausal women, age, smoking status, alcohol consumption, physical activity, diabetes, parity, age of menarche, and hormonal replacement therapy duration were adjusted. *Reference.