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摘要

Weiss suggests that the declining incidence of invasive breast cancer, which we reported recently, could be due to increased recognition and treatment for in situ cancer. Closer examination of trend data indicates otherwise. Improvements in medical practice usually are manifested in age-period-cohort analyses as changes in the calendar period pattern of disease risk, because such improvements tend to affect the health of people simultaneously in multiple age groups when they are introduced. For example, greater use of mammography led to remarkably similar calendar period increases of in situ breast cancer incidence rates after 1982 for women in all decades of age between 20 and 69 years-of-age. For both invasive breast cancer incidence rates and breast cancer mortality rates, however, a change in the birth cohort pattern of risk is apparent for white and black U.S. women, namely, moderation in the birth cohort risk for women born after 1945.