Multi-ethnic differences in breast cancer: current concepts and future directions.

Abstract

Breast cancer poses a serious public health concern throughout the world in both developed and developing nations. Recent data show a small decline in breast cancer mortality in the United States and Northern Europe where the disease has been a leading cause of death.' This reduction has been attributed in part to the early detection of breast cancer in addition to advances in clinical management. The decline in mortality has also been postulated to be due to a decreased risk in women developing breast cancer in the last 2 decades associated with increased fertility as part of the post-Second World War baby boom. 1 Despite these encouraging results, other European nations such as Spain, Portugal, Greece, Hungary, Poland and Italy have not reported a reduction in breast cancer mortality. The true reasons for these breast cancer trends, particularly across continents, remain perplexing to both epidemiologists and clinicians. Any observed variation of incidence and oncologic outcome between different populations and ethnic backgrounds may relate to the underlying biological behavior of breast cancer at the cellular and molecular level. Application of biomarker studies could therefore enhance the information obtained from classical study designs and further expand the areas of scientific inquiry to which epidemiology can contribute. This approach may yield important clues in breast cancer pathogenesis, develop potential preventive strategies, improve early detection and treatment of disease with distinctive protocols, tailored to the needs of individual target populations. Conclusions from the workshop on Multicultural Aspects of Breast Cancer Etiology in Washington DC by the Etiology working group of the National Action Plan on Breast Cancer (NAPBC) in March 1999 highlighted the importance of ethno-oncology that addresses the comparison of population groups with extreme differences in the rates of incidence, mortality and survival. 2 This article reviews the evidence for global multiethnic differences in breast cancer outcome and discusses the future clinical implications of ethno-oncology.