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Stakeholder’s Perspective: Physician

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In laboratory experiments, we can nearly guarantee that the intervention being tested is received, short of human error. We cannot control whether the patient arrives at the clinic, but when we prescribe medications that are given intravenously, we can very accurately record whether the medication was administered. With oral medications, however, there are many black holes both in research and clinical settings, and despite the best efforts to measure adherence, the impact of nonadherence is largely unknown. Nonetheless, in oncology, the availability and use of oral agents is increasing each year, and thus consideration of adherence becomes more and more important in the care of cancer patients.

One might assume that oncology patients would have greater reasons to be strictly adherent to their prescribed medications compared with, for example, patients with hypertension. However, in reality, many of the reasons causing a hypertensive patient to not reliably take his or her daily blood pressure control medication(s) are the same as those faced by a patient with cancer. As an oncologist, the knowledge that adherence is not going to be 100%, and may even be less than 50%, is critical in evaluating treatment options for a patient. Unfortunately, the factors to consider are not fully known. For example, if a patient with renal cancer takes only 75% of the planned doses, will that impact the efficacy of the treatment? Indeed, clinical trials may report on adherence to the study medication in the actual trial. However, for the most part, the reliability of reported adherence rates is questionable, and whether a lower rate of adherence will have an impact on outcomes in general is unknown. As Dr Hansen noted, some studies have associated lower adherence rates with worse outcomes, but the factors impacting nonadherence may also impact the outcome, and whether lower adherence will impact outcomes similarly in all patients is not known.  

From my perspective as a practicing oncologist, the potential for nonadherence must be considered when deciding what treatments to recommend. In some instances, an oral drug is either the only or the best option for a patient. For example, nearly all of the recently approved options for metastatic renal cancer are oral agents. We need to discuss with our patients the assumed importance of adherence to their treatment and explore with them potential barriers to adherence and how those barriers might be managed. In some cases, oral and intravenous equivalents may be available. In these cases, the oncology team should evaluate the likelihood of adherence versus risk of nonadherence with each form of the medication to help decide, with the patient, which method of administration would be the better option for that patient.

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