Potentially inappropriate medication use in older patients with breast and colorectal cancer.

<bold>Background: </bold>The objective of this study was to determine patient characteristics associated with potentially inappropriate medication (PIM) use and its impact on outcomes for patients with breast or colorectal cancer receiving adjuvant chemotherapy.<bold>Methods: </bold>The Surveillance, Epidemiology, and End Results database, linked to Medicare claims, was used. The cohort included patients who were 66 years old or older and were diagnosed with stage II or III breast or colorectal cancer between July 1, 2007, and December 31, 2009. The Drugs to Avoid in the Elderly (DAE) list and the Beers criteria were used to identify PIM use. Univariate/multivariate logistic regression determined the association of baseline PIMs with covariates. Event-free survival (EFS) was defined as the time from chemotherapy initiation to the first emergency room (ER) visit, hospitalization, death, or a composite until 3 months after chemotherapy. Cox proportional hazards modeling determined the association of PIMs with EFS.<bold>Results: </bold>The analysis included 1595 patients with breast cancer and 1528 patients with colorectal cancer. The baseline PIM frequencies were 22.2% (according to the DAE list) and 27.6% (according to the Beers criteria) in the breast cohort and 15.5% (according to the DAE list) and 24.8% (according to the Beers criteria) in the colorectal cohort. Among patients with breast cancer, 37.5% had at least 1 adverse outcome; associations included the use of ≥5 medications, an advanced stage, higher comorbidity, and prior ER visits/hospitalizations. Baseline PIM use according to the DAE list was associated with an increased risk of death in patients with breast cancer. Among patients with colorectal cancer, 45% had at least 1 adverse outcome, and associations included the use of ≥5 medications, older age, female sex, and higher comorbidity. A time-to-event analysis revealed no association between baseline PIM use and most outcomes.<bold>Conclusions: </bold>These findings require further prospective confirmation, but they support a correlation between polypharmacy and adverse outcomes for cancer patients and call into question the association with PIMs. Cancer 2018;124:3000-7. © 2018 American Cancer Society. [ABSTRACT FROM AUTHOR]