Mammography use, breast cancer stage at diagnosis, and survival among older women

BACKGROUND: Women age 65 years and older account for most newly diagnosed b reast cancers and deaths from breast cancer. Yet, older women are least lik ely to undergo mammography, perhaps because mammography's value is less wel l demonstrated in older women. OBJECTIVE: To investigate the relationship between prior mammography use, c ancer stage at diagnosis, and breast cancer mortality among older women wit h breast cancer. DESIGN: Retrospective cohort study using the Linked Medicare-Tumor Registry Database. SETTING: Population-based data from three geographic areas included in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SE ER) program. PARTICIPANTS: Women aged 67 and older diagnosed with a first primary breast cancer, from 1987 to 1993, residing in Connecticut, metropolitan Atlanta, Georgia, or Seattle-Puget Sound, Washington. MEASUREMENTS: Medicare claims were reviewed and women were classified accor ding to their mammography use during the 2 years before diagnosis: nonusers (no prior mammograms), regular users (at least two mammograms at least 10 months apart), or peri-diagnosis users (only mammogram(s) within 3 months b efore diagnosis). Mammography utilization was linked with SEER data to dete rmine stage at diagnosis and cause of death. Our main outcome variables wer e (1) stage at diagnosis, classified as early (in situ/Stage I) or late (St age IT or greater), and (2) breast cancer mortality, measured from diagnosi s until death from breast cancer or end of the follow-up period (December 3 1, 1994). RESULTS: Older women who were nonusers of mammography were diagnosed with b reast cancer at Stage II or greater more often than regular users (adjusted odds ratio (OR), 3.12; 95% confidence interval(CI), 2.74-3.58). This assoc iation was present within each age group studied. Nonusers of mammography w ere at significantly greater risk of dying from their breast cancer than re gular users for all women (adjusted hazard ratio (HR), 3.38; 95% CI, 2.65-4 .32) and for women within each age group. Even assuming a lead time of 1.25 years, nonusers of mammography continued to be at increased risk of dying from breast cancer. Our findings remained significant for all women and for the two youngest age groups (67-74 years,, 75-85 years), although the bene fit was no longer statistically significant for the oldest women (85 years and older). CONCLUSIONS: Older women who undergo regular mammography are diagnosed with an earlier stage of disease and are less likely to die from their disease. These data support the use of regular mammography in older women and sugge st that mammography can reduce breast cancer mortality in older women, even for women age 85 and older.