Breast cancer incidence rates in England are lower in black and South Asian women compared with white women, but the reasons for these differences have not been fully understood. Data from the Million Women Study showed that South Asian women had an 18% lower rate of breast cancer compared with white women, and black women had a 15% lower rate of breast cancer compared with white women.
South Asian and black women drink less alcohol and have more children than white women – and both these factors influence the risk of developing breast cancer. But when these, and other lifestyle and reproductive factors were excluded from the analysis, the risk of developing breast cancer was found to be similar for women of all ethnic groups.
Many of the black and South Asian women in the study were first-generation immigrants. And it is likely that as second and subsequent generations of women of ethnic minority origin change their lifestyles, their risk of breast cancer will increase.
Study author Dr Toral Gathani from the University of Oxford, said: “In this study of largely postmenopausal women in England, we see that the lower risk of breast cancer in South Asian and black women is largely explained by differences in lifestyle and reproductive patterns. It’s important for women of all ethnic groups to understand what are the modifiable risk factors for breast cancer, such as obesity and excessive alcohol consumption, and to take measures to reduce their risk.”
The study, funded by Cancer Research UK and the Medical Research Council, is following the health of than one million white women, almost 6,000 south Asian women and almost 5,000 black women in England. Women were recruited between 1996 and 2001, when they were aged 50-64 years, and filled in questionnaires asking about their lifestyle and other risk factors. Information on breast cancer was obtained from National Health Service cancer registries.
Source: Ethnic differences in breast cancer incidence in England are due to differences in known risk factors for the disease: prospective study. T Gathani, et al. British Journal of Cancer (2014) 110, 224–229. Published online 29 October 2013.