Adiposity, adult weight change and breast cancer risk in postmenopausal Japanese women: the Miyagi Cohort Study

Abstract

Background:The role of adult weight change in breast cancer (BC) risk is unclear in Japanese women.Methods:A total of 10 106 postmenopausal women aged 40–64 years (the Miyagi Cohort) were followed from 1990 to 2003, and 108 BC cases were identified. Hazard ratios (HRs) were estimated according to body mass index (BMI) at the current age and at the of age 20 years, and weight change since age 20 years.Results:Higher current BMI was associated with an increased risk of BC (P for trend=0.02), whereas higher BMI at the age 20 years was inversely associated with this risk (P for trend=0.002). There was a significant association between weight change since age 20 years and BC risk (P for trend=0.0086). Compared with stable weight, HR was 0.35 for weight loss of 5 kg or more (P for weight loss trend=0.04) and 1.55 for weight gain of 12 kg or more (P for weight gain trend=0.05).Conclusion:Adiposity at younger and current age has differential effects on BC risk among postmenopausal women; weight gain in adulthood being associated with an increased, and weight loss with a decreased risk.

Differential impact of body mass index and its change on the risk of breast cancer by molecular subtype: A case-control study in Japanese women

“…The association between high BMI or adult weight gain and breast cancer risk for postmenopausal women has been established, and found to be partly attributable to an increase in circulating endogenous estrogen levels from adipose tissue, the primary source of estrogen in postmenopausal women (Han et al 2006;Kawai et al 2010;Eliassen et al 2006). These findings are supported by the fact that the association between BMI and risk of postmenopausal breast cancer is stronger for estrogen receptor (ER)-positive than -negative tumors (Feigelson et al 2006;Vrieling et al 2010;Suzuki et al 2011).…”

“…The mechanisms underlying this inverse association remain to be elucidated. Several studies have suggested that women who are obese prior to menopause are likely to have ovulatory insufficiency or anovulatory cycles, resulting in decreased estrogen and progesterone levels (Suzuki et al 2011;Baer et al 2010;Kawai et al 2010;Key & Pike 1988), and we accept this theory in interpreting our present result. However, given our limited number of subgroup subjects and the inconsistent results across studies, additional studies with sufficient numbers of subjects of various ethnicities are needed.…”

“…Several studies have suggested an inverse association between body weight in early adulthood and the risk of breast cancer (Suzuki et al 2011;Baer et al 2010;Kawai et al 2010), but others have found no significant association (Sanderson et al 2002;Okasha et al 2003). A conclusive answer to this issue awaits further study.…”

Hip circumference is associated with the risk of premenopausal ER−/PR− breast cancer

“…They found no association in the ERÀ/PRÀ subgroup. Althuis et al 4 in their review of the literature, Chen et al 3 in their meta-analysis and more recently Kawai et al, 25 Parr et al 26 and Singh et al 27 also concluded to an increased risk of postmenopausal breast cancers associated with high BMI; this risk was more pronounced for cancers with positive receptors than those with negative receptors. It has been suggested that risk factors associated with ER þ /PR þ breast cancer may operate through exposure to estrogen and progesterone, unlike those associated with ERÀ/PRÀ breast cancer, which may involve mechanisms independent of steroid exposure.…”

Body Mass Index and Risk of Breast Cancer: A Systematic Review and Meta-Analysis in Iran

“…Since data of 8 summaries were not accessible or were not appropriate, there is a possibility of publication bias. We recommend Iranian women to be aware of effect of weight on breast 4 Int J Cancer Manag. 2017; 10(4):e5921.…”