Difficult to swallow: issues affecting optimal adherence to oral anticancer agents

The number of anticancer drugs currently available in oral formulation has increased dramatically over the past 15 to 20 years, especially with the recent development of new hormonal and targeted therapies. At present, approximately 25% of all cancer drugs are available in oral formulation, with numbers expected to increase exponentially in the coming years. The convenience associated with the self-administration of oral therapy, the requirement of fewer trips to the physician's office, and the lack of infusion reactions are all benefits for patients, allowing them to potentially maintain their relative independence while undergoing active anticancer treatment. On the other hand, there are growing concerns regarding patients' poor adherence to oral therapy as well as the challenges of monitoring patient compliance when treatment administration does not occur in the presence of health care professional (HCPs). More importantly, poor adherence to proven therapies may detrimentally affect the patients' clinical outcomes, such as survival. Thus, there is an urgent need to identify more effective strategies to measure and monitor adherence to oral anticancer agents in an effort to maximize their therapeutic benefits.