Leisure Time Physical Activity Is Associated with Substantial Reduction in Risk of Breast Cancer and Breast Cancer Subtypes in Nigerian Women (P16-007-19)

Abstract

Abstract Objectives To examine the association between leisure-time physical activity (LTPA) and breast cancer in Nigerian women. The hypothesis was that LTPA decreased breast cancer cases in Nigerian women. To examine the association between LTPA and estrogen receptor positive (ER+), triple negative breast cancer (TNBC+), Luminal A breast cancer in Nigerian women. The hypothesis was that LTPA decreased breast cancer subtypes in Nigerian women. Methods We enrolled 739 newly diagnosed primary invasive breast cancer and 739 age-matched controls in Nigeria from 01/2014 to 07/2016. This analysis is restricted to the 40% of cases for whom we have complete ER, TNBC, and Luminal-A data and their matched controls. We derived the average amount of time per week spent on LTPA over the past year using a modified Nurses’ Health Study II PA questionnaire. LTPA was calculated from the total metabolic equivalent (METs) assigned for each reported physical activity hour/week (i.e., walking, cycling, and dancing). We examined LTPA by comparing participants who attained the WHO physical activity recommendations of at least 150 minutes of moderate-intensity or/and 75 minutes of vigorous-intensity aerobic activity weekly with those who did not. We used conditional logistic regression to estimate the adjusted Odds Ratio (OR) of LTPA and overall as well as subtypes of breast cancer. Results The mean (SD) age of cases was 41.6 (9.1) and controls 43.9 (11.8) years. Women who attained the WHO physical activity recommendations had 43% decreased the risk of breast cancer (OR = 0.57, 95% CI:0.42–0.77) compared with those who did not, after controlling for demographic, anthropometric and fertility-related factors. LTPA was also associated with reduced risk of breast cancer subtypes by 41% for ER+, 59% for TNBC+and 59% for Luminal A. Conclusions Physical activity is associated with reduced risk of breast cancer overall and by subtypes in Nigerian women. Funding Sources Training Program in Nigeria for Non-Communicable Diseases Research (TRAPING NCD) grant number FIC/NIH D43TW009106 from the Fogarty International Centre. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Fogarty International Centre or the National Institutes of Health.