Introduction: Cancer patients tend to prefer oral instead of parenteral chemotherapy. To date, there is little evidence on the medication adherence in cancer patients. We investigated medication adherence to tyrosine kinase inhibitors in patients suffering from non-small cell lung cancer.
Methods: Tyrosine kinase inhibitor adherence was measured electronically by MEMS® (medication event monitoring system) over at least six months. Adherence rates were calculated in terms of Dosing Compliance, Timing Compliance, Taking Compliance, and Drug Holidays. Patients were dichotomized as adherent when Dosing Compliance and Timing Compliance were ≥80%, Taking Compliance ranged between 90 and 110%, and <1 Drug Holiday was registered. Quality of life was assessed by two questionnaires (EORTC QLQ-C30 version 3.0, EORTC QLQ-LC13) at three time points. Adverse drug events were reported via patient diaries.
Results: Out of 32 patients enrolled, data from 23 patients were evaluable. Median Dosing Compliance, Taking Compliance, and Timing Compliance adherence rates of tyrosine kinase inhibitor intake amounted to 100%, 98%, and 99%, respectively; Drug Holidays were observed in three patients. Four patients were dichotomized as non-adherent. Three of them had a twice-daily tyrosine kinase inhibitor regimen. Median quality of life scores amounted to 67 (max. 100) and remained unchanged over the study period. Fatigue and rash were the most frequently reported adverse drug events.
Conclusion: Medication adherence of non-small cell lung cancer patients treated with tyrosine kinase inhibitors was extraordinarily high and is likely to support the effectiveness of tyrosine kinase inhibitor treatment and a good quality of life over a long period of time. Adherence facilitating information and education is especially relevant for patients taking tyrosine kinase inhibitors in a twice-daily regimen.
Keywords: Lung cancer; electronic adherence measurement; medication adherence rate; quality of life; tyrosine kinase inhibitor.