Differences in screening mammography outcomes among White, Chinese, and Filipino women.

BACKGROUND: The accuracy of screening mammography among Asian women in the United States has received little attention. We determined whether the accuracy of screening mammography for Chinese and Filipino women differs from that of white women.

METHODS: We examined a cohort of white, Chinese, and Filipino women 40 years and older who underwent 200,402, 72,604, and 19,087 screening examinations, respectively, between January 1986 and December 2001 in San Francisco County, California, of whom 2177 were diagnosed with breast cancer within 12 months of a screening examination. By linking screening examinations to the regional Surveillance, Epidemiology and End Results program and the California Cancer Registry, we identified the occurrence of any invasive cancer or ductal carcinoma in situ and then calculated the rate of cancer per 1000 screenings and the sensitivity of mammography.

RESULTS: The rate of invasive breast cancer per 1000 screenings was 45% lower for Chinese than for white women aged 50 to 69 years (3.8 vs 6.9; P<.001) and 29% lower for Filipino than for white women (4.9 vs 6.9; P = .03). Rates of ductal carcinoma in situ were similar across all ethnic groups (1.6-1.7 per 1000 screenings; P>or=.60). The sensitivity of mammography was similar for white, Chinese, and Filipino women (81.6%-84.3%; P>.30).

CONCLUSIONS: Screening mammography has similar accuracy among white, Chinese, and Filipino women, although the absolute benefit of screening, in terms of breast cancer deaths averted, is likely to be less among Asian women because the rates of invasive cancer are lower compared with white women of similar age. Overdiagnosis of ductal carcinoma in situ with screening mammography among Asian women is likely to be comparable to that of white women because the rate of ductal carcinoma in situ was similar in all the examined ethnic groups.