Objective: To assess the factors related to potentially inappropriate medication (PIM) use in elderly patients with cancer, as well as to compare the PIM prevalence in older adults with and without cancer. Methods: Data from the Surveillance, Epidemiology, and End Results-Medicare-linked base (2009–2011) were accessed to conduct a retrospective study comparing patients with cancers of the breast, colon/rectum, and prostate against a matched population of subjects without cancer. PIM use was defined based on the 2015 Beers Criteria and was quantified using prescription claims. Multivariable logistic regression models were used to assess the associations between the patients’ characteristics, clinical factors, and PIM use in patients with cancer based on Beers criteria. Propensity score matching was applied to compare use of PIM in patients with versus without cancer. Results: PIM usage rates in patients with colorectal and breast cancers were significantly higher than non-cancer-bearing adults; the difference in PIM usage rate was not significantly different in the prostate cancer-matched cohort. The prevalence of inappropriate medication use in the three types of cancers evaluated was directly correlated with number of medications prescribed, treatment with chemotherapy, and co-morbid medical problems. Conclusion: Patients diagnosed with cancer were more likely to use PIM compared with their non-cancer counterparts. The updated Beers criteria has the potential to serve as an important tool in geriatric oncology practice but it may still need to take into consideration different cancer types and their respective treatments.