Correlation of blood sex steroid hormones with body size, body fat distribution, and other known risk factors for breast cancer in post-menopausal Chinese women

Objective: Estrogen plays a central role in breast cancer. It has been suggested that many known breast cancer risk factors may exert their effect via levels of endogenous sex hormones. The objective of this analysis is to evaluate the association between measures of body size, dietary macronutrient intake, and reproductive factors with levels of endogenous sex hormones among women living in Shanghai, China. Methods: Included in this study were 420 post-menopausal healthy women randomly selected from the general population as controls who participated in the Shanghai Breast Cancer Study, a population-based case - control study conducted in Shanghai, China between 1996 and 1998. Comprehensive dietary and reproductive information was collected using a structured questionnaire during an in-person interview and anthropometrics were measured by trained interviewers according to a standard protocol. Hormone levels were log-transformed and Pearson correlation coefficients were calculated to determine the correlation between hormone levels and selected breast cancer risk factors. Results: Measures of body size were strongly correlated with hormone levels. In particular, weight, waist circumference, and hip circumference were significantly positively correlated ( p < 0.05) with levels of testosterone, estradiol, estrone, and significantly negatively correlated with sex hormone binding globulin. Macronutrient intake and reproductive factors were not correlated with endogenous sex hormone levels. Conclusions: These data suggest that breast cancer risk associated with measures of body size may be mediated, at least partially, by levels of endogenous sex hormones.