Self-Reported Adherence to Capecitabine on XELOX Treatment as Adjuvant Therapy for Colorectal Cancer

Adherence has become an important issue in modern oncology treatment. Most studies have included heterogeneous target tumor types, regimens, and therapy settings. Our study focused on capecitabine during capecitabine plus oxaliplatin (XELOX) treatment as an adjuvant therapy for colorectal cancer. The main aims of this study were to evaluate real-life adherence to capecitabine and to investigate candidate factors that might decrease adherence. We studied 338 consecutive patients who received XELOX treatment between December 1, 2011, and April 30, 2015, at the Cancer Institute Hospital of the Japanese Foundation for Cancer Research. Our study assessed adherence to capecitabine through patient-reported treatment diaries and interviewed nonadherents to determine the reasons for not taking capecitabine at a pharmaceutical outpatient clinic. We calculated the adherence rate in a cycle as: number of times the patient took capecitabine/28. Relative dose intensities and factors associated with deteriorating adherence to capecitabine were retrospectively surveyed from electronic patient records. Uni- and multivariate logistic regression analyses were used to investigate factors associated with optimal adherence. The study covered 282 patients who received 2,055 cycles of XELOX. Median adherence rate was 94.0% in the first cycle, and median relative dose intensity of capecitabine was 77.8%. The most common reasons for nonadherence were nausea/vomiting and diarrhea. The presence of the following factors was not significantly associated with adherence: ECOG performance status ≥1 (p = 0.715), clinical stage (p = 0.408), primary tumor site (p = 0.576), age ≥70 years at study entry (p = 0.757), female gender (p = 0.504), and not living alone (p = 0.579). The adherence rate from this study was significantly higher than the adherence from metastatic settings. Adherence-enhancing interventions for capecitabine in XELOX treatment as adjuvant therapy comprised management of nausea/vomiting and diarrhea.