Multicenter observational study on adherence and acceptance of lapatinib treatment in patients with HER2+ metastatic breast cancer.

Abstract

e11102 Background: Lapatinib, an oral tyrosine kinase inhibitor, is active in combination with capecitabine in women with HER2-positive metastatic breast cancer that has progressed after trastuzumab-based therapy. Patient sharing and adherence are critical in evaluating the effectiveness of an oral therapy. We investigated the level of therapy approvement, the rates and predictors of nonadherence to anti-HER2 oral therapy in patients enrolled. Methods: Between January 2010 and November 2010, patients with HER2+ metastatic breast cancer eligible for treatment with lapatinib were enrolled. The level of acceptance was evaluated using a questionnaire with sixteen questions administered every 3 months thereafter during the treatment. Patients scored each item on a 5-point ordinal scale range ranging from 0 to 4 during the previous 7 days. Medication adherence was estimated monthly from three sources of data: patient-completed medication diaries, self-report during the physician interview, and the pharmacy control of the drug box. Results: Overall, 69 patients were enrolled. Median age was 57 years (range, 34 to 71 years), 34 received a previous oral therapy, and 20 had at least one comorbidity. Forty women were married, 29 had high school qualification, 21 patients were homemakers. In total, 441 cycles of therapy were administered, with a median of 6.4. Overall acceptance of therapy did not change during the treatment. Adherence was 82% across all cycles, and adherence did not vary by cycle. Dosing violations occurred in 45 of the patients (65%). Adherence was not related to age, tumor stage, or performance status. On the other hand the marital status and the educational qualification influence the adherence. Conclusions: Our results suggest that despite the advanced disease, most women accept the therapy with lapatinib without any difficulties. Patients with metastatic breast cancer were adherent to oral target therapy. The level of adherence depend on cultural, familiar and social factors.