Influence Of Diet, Physical Activity, Body Size On Breast Cancer In South Africa: A Study Of Women In Transition

Sabina RINALDI, International Agency for Research on Cancer, France
JOFFE M. 2 , NORRIS S. 2 , VORSTER E. 4 , TALJAARD C. 4 , CUBASCH H. 3 , ROMIEU I. 1

1 International Agency for Research on Cancer, Lyon, France
2 MRC/Wits Developmental Pathways for Health Research Unit, University of the Witwatersrand, Johannesburg, South Africa
3 Batho Pele Breast Unit, Chris Hani Baragwanath Academic Hospital, Soweto, South Africa
4 Faculty of Health Sciences, North-West University (Potchefstroom Campus), Potchefstroom, South Africa

Purpose
There are suggestions of a different epidemiology of breast cancer (BC) in women of African ethnicity, a burden that appears in younger women with a higher proportion of ER- cases. Influences of diet, body fatness and physical activity on BC need to be investigated in African women in Africa because of the uniqueness of this population in rapid lifestyle transition, where BC has now become one of the most common incident cancers in women. Large differences between urban and rural populations in terms of dietary intake upon urbanisation, and lack of physical activity leading to obesity have been shown in South Africa, and prevalence of overweight and obesity is high. We have set up a population-based case-control study at the Baragwanath Hospital in Soweto, South Africa (The SABC study) to study BC etiology.
 Methods
Questionnaire data on lifestyle, reproductive factors, physical activity/inactivity, and diet are collected from all women, as well as biological samples (serum, plasma, red blood cells, buffy coat and urine), which are stored at -80C. Anthropometry is measured for all women, who also undergo dual-energy X-ray absorptiometry and computed ultrasonography. Statistical differences between cases and controls for preliminary results were analysed by logistic regression models adjusting for potential confounding factors.
Results
To date, 118 cases and matched controls have been recruited in the study. 55% of the cases are classified as luminal A, and 15% as triple negative. Preliminary analyses showed no associations between obesity and pre-menopausal BC, while a strong inverse association was observed in post. High physical activity was protective against BC in all women.
 Conclusions
Preliminary data indicate strong associations of lifestyle factors with BC risk in this population. The study will recruit a total of 500 cases and controls over the next 2 years.
Funding sources
WCRF grant 2012/591