Reduced mammographic screening may explain declines in breast carcinoma in older women

OBJECTIVES: To examine whether declines in breast cancer in the oldest-old women correspond with declines in the use of cancer testing. DESIGN: Cross-sectional evaluation of three databases. SETTING: Public access data. PARTICIPANTS: Cases recorded in the California Registry and the Surveillance, Epidemiology, and End Results Program between 1988 and 1997. The study also included respondents to the 2002 Centers for Disease Control and Prevention Behavioral Risk Factor Surveillance System. MEASUREMENTS: Cancer incidence and self-reported mammography within the previous 2 years. RESULTS: Most previous analyses have combined all individuals aged 75, 80, or 85 and older. Creating separate categories for age ranges 85 to 89, 90 to 94, 95 to 99, and 100 and older suggests different incidence patterns for a variety of cancers, including mammary carcinoma in situ (CIS). Between the ages of 40 and 74, there is a significant rise in CIS. Beginning at age 75, there is a significant decline in CIS through the highest age categories. The use of mammographic screening increases between the ages of 40 and 60. Beginning at age 75, there is a significant decline in the use of mammography that parallels the decline in incident cases of CIS. CONCLUSION: There may be a substantial reservoir of undiagnosed CIS in the population. Surveillance bias might explain the decreasing incidence of CIS with advancing age in the oldest age groups. Autopsy studies are needed to estimate the true prevalence of CIS in older women.