Strengthening Global Partnership in Breast Cancer Research

The global diaspora of peoples has major implications for health and disease and can provide critical insights for understanding etiology and improving treatment. Historically, for example, women in East Asia have experienced lower risks of breast cancer than women of European descent living in Europe and North America. Studies on women of East Asian descent who migrated to North America, however, have demonstrated rates of breast cancer comparable to those of women of European descent among second-generation immigrants, with intermediate rates among first-generation women. The Michigan-Ghana study team report a higher proportion of triple-negative breast cancer (TNBC) among women in West Africa compared with women of European descent living in North America, with North American women of mixed African and European descent falling in between the two proportions. Because TNBC is most common among women with premenopausal onset of breast cancer, the age distribution of the reported patients with breast cancer is important to consider. Theauthors state that the rankingspersisted among women younger than age 50 years. More recently, the Michigan-Ghana group has expanded their work to include breast cancers among Ethiopian women. Rates of TNBC are much lower among these women compared with those in West Africa, consistent with genetic admixture with peoples of Arab descent. Their preliminary work suggests potential biologic underpinnings, which hopefully will be followed by more expansive investigations of multiple factors. A key remaining question is to what extent these observed differences in the proportion of specific subtypesofbreast cancerarea result of underlying genetic factors, constitutional or environmental factors, or, most likely, a combination of these risk factors. Studying differences in exposures across varied populations may help in detecting clues for prevention.