Association between adherence to oral therapies in cancer patients and clinical outcome: A systematic review of the literature

Aims: Adherence to therapy is a key factor in successful treatment. The aim of this systematic review is to assess the extent to which patients with better adherence to oral therapy have better clinical outcomes among cancer patients.

Methods: All studies published in PubMed up to 20 October 2020, which considered the use of oral anticancer drugs for cancer patients and which correlated treatment adherence with a clinical outcome, were considered.

Results: From the 42 studies considered in the systematic review, 14 were for oncological indications and 28 for haematological indications. There was considerable variance in calculation methods, outcomes considered, and in the definitions of adherence. However, it emerged that most studies reported a significant correlation between adherence to therapy and clinical outcome.

Conclusion: As adherence to therapy is a key factor in achieving a better clinical outcome, future studies with large samples, robust endpoints and the use of at least two methods of assessing adherence would be desirable in order to produce more robust evidence.