Screening mammography in Asian American women.

Abstract

A recent article by Leung et al.,1 concluding that annual, population-based screening mammograms are not justified in Hong Kong, would seem to have implications for screening of Asian women in Western countries. In US Asian/Pacific Islander women aged 50 years or older, for example, 1996 breast cancer incidence and mortality rates were 126.4 and 32.7 per 100 000, respectively,2 similar to rates in Hong Kong. Following the calculations described by Leung et al., we calculated a screening prevalence of 149.8 per 100 000 and assumed 95% sensitivity, 99.1% specificity, and an 8% complication rate among 18.6% of healthy women receiving biopsies after a false-positive result. Among 100 000 women screened annually for 10 years, we would expect 8987 of 10 410 positive results to be false, with 134 of these women suffering biopsy complications. If 100 000 women were screened annually for 10 years, 65 breast cancer deaths would be prevented; 1529 women would need to be screened over 10 years to prevent 1 breast cancer death (although the mortality benefit might be underestimated if the lower breast cancer mortality rate in Asian American women reflects earlier detection). Relaxing screening guidelines for Asian Americans might be justified on the basis of these calculations. On the other hand, screening guidelines already in place in the United States, controversial or not, raise the standard of our expectation: any cancer death resulting from late detection is one that should have been prevented. Moreover, assigning low-risk status on the basis of ethnicity raises another concern—that it might contribute to a belief that Asian women are inherently at lower risk for breast cancer, when they are not. Breast cancer rates are known to rise in Asian migrants to Western countries,3 and they are rising with “Westernization” in Asian countries as well.4,5 Ethnicity is merely a surrogate for the suspected but largely unidentified factors that actually do confer lower risk. From a research perspective, what is needed is a better characterization of the rapid transition in breast cancer risk that Asian women in Western and Asian countries are undergoing and a better understanding of the social, economic, cultural, and biological factors contributing to this increase in risk. Ideally, a clearer understanding of these issues will contribute to preventive strategies and efforts toward more targeted screening. With respect to implications for screening, Asian American women as a group clearly stand to benefit less by following guidelines designed for a higher-risk population. But as long as our conception of their low-risk status rests on their ethnicity, without a clear understanding of the factors underlying their lower risk, a wholesale relaxation of guidelines for only this subset of the population is problematic. Decisions on how strictly to adhere to standard screening guidelines might best be left to individual physicians and their patients.