Mammographic Surveillance in Older Women With Breast Cancer in Canada and the United States: Are We Choosing Wisely?

Abstract

Guidelines on mammographic surveillance after breast cancer treatment have been disseminated internationally and incorporated into Choosing Wisely recommendations to reduce low-value care. However, adherence within different countries before their publication is unknown. Low-value mammography, defined as "short-interval" (within 6 months of radiation) or "high-frequency" (>1 within 12 months of radiation), was compared in Medicare fee-for-service in the United States and Ontario, Canada. Women ≥65 years diagnosed with breast cancer who underwent breast-conserving therapy with a minimum of 24 months of follow-up were included (n = 19,715 United States; 6479 Ontario). Secondary outcomes were patient and physician characteristics associated with discordance. Short-interval mammography was higher in the United States than in Ontario (55.9% vs 38.0%, P < .001), as was high-frequency (39.6% vs 7.9%, P < .001). In Ontario, younger age (42% ≥85 vs 58% <74 years, P < .001) and chemotherapy (69% vs 51%, P < .001) were associated with short-interval mammography; in the United States, age, earlier diagnosis year, stage, chemotherapy, rurality, and academic center treatment were associated with greater use. Chemotherapy was associated with high-frequency mammography in both countries (13% vs 7% in Ontario, P < .001; 69% vs 51% in United States, P = .02); younger age, earlier diagnosis year, stage, and nonacademic center treatment were associated in the United States. In both countries, radiation oncologists had the highest proportion of providers ordering low-value mammograms. Despite significant evidence guiding surveillance mammography recommendations, there are high rates of short-interval mammography in both the United States and Ontario, and high rates of high-frequency mammography in the United States. Further international efforts, such as Choosing Wisely, are needed to reduce low-value mammography.