The risk of developing breast cancer within the next 5, 10, or 20 years of a woman’s life Original Research Article

Background: The lifetime risk of developing breast cancer is a frequently misinterpreted statistic. Risk projections over a shorter time period, conditioned on current age, may be less prone to misconceptions and more relevant to populations at different ages. The purpose of this study was to estimate the risk of developing breast cancer within the next 5, 10, or 20 years for women currently aged 30 to 70 years in California’s four major race/ethnic groups. Methods: Life tables were used to obtain risk estimates based on 1993–1997 breast cancer incidence rates from the California Cancer Registry and statewide mortality rates. Results: For women currently aged 50, the estimated risk of developing invasive breast cancer within 5 years varied from 0.8% (1 in 133) among Hispanics to 1.3% (1 in 75) among Caucasians. Risk estimates within 10 years were 2.9% (1 in 34) among Caucasians, 2.3% (1 in 43) among African Americans, 2.0% (1 in 51) among Asian/Pacific Islanders, and 1.6% (1 in 63) among Hispanics. Within 20 years, estimated risks increased to 6.6% (1 in 15) among Caucasians, 5.0% (1 in 20) among African Americans, 3.9% (1 in 26) among Asian/Pacific Islanders, and 3.7% (1 in 27) among Hispanics. Risk estimates were 8% to 20% higher when in situ tumors were included in the calculations. Conclusions: Based on these estimates, the baseline risk of developing breast cancer in the next 1 or 2 decades of life varies by race/ethnicity and current age, but may be lower than the risk perceived by most women.