OBJECTIVES : The prevalence of cancer survivorship is increasing. Compared to patients without a history of cancer, cancer survivors are more likely to develop chronic conditions and have poorer health outcomes overall. Nonadherence to chronic medications may further contribute to these outcomes. Cancer survivors face a variety of barriers to medication adherence, including financial and attitudinal. Patient characteristics may be associated with nonadherence. While most literature on cancer survivorship has been focused on patterns and predictors of screening behaviors, the goal of this study was to examine factors associated with chronic medication nonadherence in cancer survivors.

METHODS : A systematic literature search of MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, CINAHL, and Web of Science through July 2019 was performed to identify case-control and cohort studies evaluating factors contributing to nonadherence to chronic disease medications amongst survivors of adult cancer. Studies examining adherence to cancer-related medications, vaccines, or non-pharmacological treatments or whose populations were survivors of pediatric cancer or patients with active cancer were excluded.

RESULTS : Of 1,422 records found through database searching, 190 abstracts were screened. Fifty-seven full-text articles were assessed by two independent reviewers, yielding 16 full-text articles in the final qualitative analysis. Studies most commonly included breast cancer survivors (n = 12), using self-reported adherence data (n = 9). Studies examined demographics, health, and cost-related characteristics associated with nonadherence. Few (n = 7) studies investigated the impact of patient attitudes on medication nonadherence; some (n=2) mentioned patient perceptions of their cancer prognosis.

CONCLUSIONS : Existing studies on predictors of nonadherence to chronic medications in cancer survivors are varied in their data sources, patient populations, and predictors investigated. Publicly-available real-world data like the Medical Expenditure Panel Survey (MEPS), may provide insight into factors affecting adherence. Future studies focused on findings from MEPS may inform future interventions aimed at improving adherence in cancer survivors.