Abstract 3733: A meta-analysis of diet, physical activity and breast cancer risk: An evolutionary perspective

Abstract

The human genome was adapted to an environment different from that experienced by modern industrialized humans. The reconstruction of lifestyle, reproductive and dietary characteristics of human ancestors is therefore important in understanding breast cancer. Moreover, cultural evolution occurs at a faster rate than genetic adaptation, resulting in evolutionary discordance between modern human genes and lifestyle. This mismatch between genetic biology and modern lifestyle factors may foster the development and propagation of breast cancer because of potential impact on circulating hormones and body mass. Diet and exercise may differentially affect breast cancer risk during reproductive and menopausal years. This study examines evolutionary discordance in energy consumption, expenditure and reproductive events as it relates to risk of female breast cancer. Published literature evaluating relationships between breast cancer risk and dietary fat, and exercise was systematically reviewed up to May of 2010. Descriptive data, estimates of relative risk and 95% confidence interval (CI) were extracted from relative studies, sorted according to inclusion criteria and analyzed using the random effects model of DerSimonian and Laird. The results reveal disparity between exercise load, fat intake, study type and reproductive status. Cohort study results indicated significant summary relative risks between poly-unsaturated fat and breast cancer (1.091, 95% CI: 1.001; 1.184). In case-control studies no association between fat and breast cancer was observed. Reproductive status influenced the affect of dietary fat on breast cancer risk. Post-menopausal women exhibited a significant association between total fat (1.042, 95%CI: 1.013; 1.073), poly-unsaturated fat intake (1.22, 95% CI: 1.08; 1.381) and breast cancer. A non-significant inverse relationship between fat types and breast cancer was identified in premenopausal women. Evidence for significant inverse relationships between exercise and breast cancer were observed in all categories. In sum: a. Higher levels of exercise could decrease breast cancer risk b. Higher consumption of dietary fat may increase breast cancer risk c. Reproductive status may influence breast cancer risk in women These results have important implications for future breast cancer research. Interactions between modern cultural factors and ancestral biology may be expressed as higher rates of breast cancers in modern, industrialized nations. Clinical studies do not cumulatively examine population variations in socio-economic, cultural and biological risk factors and breast cancer occurrence. Applying an anthropological and biocultural perspective to future research could identify evolutionary roots to causes and risk factors of female reproductive diseases. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3733. doi:10.1158/1538-7445.AM2011-3733