To the Editor.
—Drs Lindfors and Rosenquist1 estimate the cost-effectiveness of several alternative mammographic screening strategies. They estimate that adding annual screening for women in their 40s to biennial screening for women 50 to 79 years of age increases the marginal cost per year of life saved (MCYLS) of screening to only $20 200. However, this estimate is based on the comparison between screening for women aged 40 to 79 years vs no screening at all, and does not reflect the true marginal cost of adding annual screening for women in their 40s.2,3 The MCYLS of screening from 40 to 79 years vs 50 to 79 years should be estimated as $32 000 ($1915 minus $1120 divided by 0.0950 year minus.0701 year). Although this MCYLS may still be considered cost-effective, it is highly sensitive to the assumed breast cancer mortality reduction in the 40- to 49-year-old age range.