Factors influencing adherence to cancer treatment in older adults with cancer: a systematic review

Cancer is a disease that mostly affects older adults. Treatment adherence is crucial to obtain optimal outcomes such as cure or improvement in quality of life. Older adults have numerous comorbidites as well as cognitive and sensory impairments that may affect adherence. The aim of this systematic review was to examine factors that influence adherence to cancer treatment in older adults with cancer. Systematic review of the literature published between inception of the databases and February 2013. English, Dutch, French and German-language articles reporting cross-sectional or longitudinal, intervention or observational studies of cancer treatment adherence were included. Data sources included MEDLINE, EMBASE, PsychINFO, Cumulative Index to Nursing and Allied Health (CINAHL), Web of Science, ASSIA, Ageline, Allied and Complementary Medicine (AMED), SocAbstracts and the Cochrane Library. Two reviewers reviewed abstracts and abstracted data using standardized forms. Study quality was assessed using the Mixed Methods Appraisal Tool 2011. Twenty-two manuscripts were identified reporting on 18 unique studies. The quality of most studies was good. Most studies focused on women with breast cancer and adherence to adjuvant hormonal therapy. More than half of the studies used data from administrative or clinical databases or chart reviews. The adherence rate varied from 52% to 100%. Only one qualitative study asked older adults about reasons for non-adherence. Factors associated with non-adherence varied widely across studies. Non-adherence was common across studies but little is known about the factors influencing non-adherence. More research is needed to investigate why older adults choose to adhere or not adhere to their treatment regimens taking into account their multimorbidity.