Potential Medication-Related Problems in Older Breast, Colon, and Lung Cancer Patients in the United States

Background: Older adults are often exposed to multiple medications, some of which could be inappropriate or have the potential to interact with each other. Older cancer patients may be at increased risk for medication-related problems due to exposure to cancer-directed treatment. Methods: We described patterns of potentially inappropriate medication (PIM) use and potential drug–chemotherapy interactions among adults age 66+ years diagnosed with stage I–III breast, stage II–III colon, and stage I to II lung cancer. Within the Surveillance, Epidemiology, and End Results–Medicare database, patients had to have Medicare Part D coverage with 1+ prescription in the diagnosis month and Medicare Parts A/B coverage in the prior 12 months. We estimated monthly prevalence of any and cancer-related PIM from 6 months pre- to 23 months postcancer diagnosis and 12-month period prevalence of potential drug–chemotherapy interactions. Results: Overall, 19,318 breast, 7,283 colon, and 7,237 lung cancer patients were evaluated. Monthly PIM prevalence was stable prediagnosis (37%–40%), but increased in the year following a colon or lung cancer diagnosis, and decreased following a breast cancer diagnosis. Changes in PIM prevalence were driven primarily by cancer-related PIM in patients on chemotherapy. Potential drug–chemotherapy interactions were observed in all cohorts, with prevalent interactions involving hydrochlorothiazide, warfarin, and proton-pump inhibitors. Conclusions: There was a high burden of potential medication-related problems among older cancer patients; future research to evaluate outcomes of these exposures is warranted. Impact: Older adults diagnosed with cancer have unique medication management needs. Thus, pharmacy specialists should be integrated into multidisciplinary teams caring for these patients. Cancer Epidemiol Biomarkers Prev; 27(1); 41–49. ©2017 AACR.