Long-term surveillance mammography and mortality in older women with a history of early stage invasive breast cancer

Abstract

Annual surveillance mammograms in older long-term breast cancer survivors are recommended, but this recommendation is based on little evidence and with no guidelines on when to stop. Surveillance mammograms should decrease breast cancer mortality by detecting second breast cancer events at an earlier stage. We examined the association between surveillance mammography beyond 5 years after diagnosis on breast cancer-specific mortality in a cohort of women aged ≥ 65 years diagnosed 1990-1994 with early stage breast cancer. Our cohort included women who survived disease free for ≥ 5 years (N = 1,235) and were followed from year 6 through death, disenrollment, or 15 years after diagnosis. Asymptomatic surveillance mammograms were ascertained through medical record review. We used Cox proportional hazards regression stratified by follow-up year to calculate the association between time-varying surveillance mammography and breast cancer-specific and other-than-breast mortality adjusting for site, stage, primary surgery type, age and time-varying Charlson Comorbidity Index. The majority (85 %) of the 1,235 5-year breast cancer survivors received ≥ 1 surveillance mammogram in years 5-9 (yearly proportions ranged from 48 to 58 %); 82 % of women received ≥ 1 surveillance mammogram in years 10-14. A total of 120 women died of breast cancer and 393 women died from other causes (average follow-up 7.3 years). Multivariable models and lasagna plots suggested a modest reduction in breast cancer-specific mortality with surveillance mammogram receipt in the preceding year (IRR 0.82, 95 % CI 0.56-1.19, p = 0.29); the association with other-cause mortality was 0.95 (95 % CI 0.78-1.17, p = 0.64). Among older breast cancer survivors, surveillance mammography may reduce breast cancer-specific mortality even after 5 years of disease-free survival. Continuing surveillance mammography in older breast cancer survivors likely requires physician-patient discussions similar to those recommended for screening, taking into account comorbid conditions and life-expectancy.