Patient preferences and treatment adherence among women diagnosed with metastatic breast cancer

Given the various profiles (eg, oral vs intravenous administration, risk of hot flashes vs fatigue) of treatment options (eg, endocrine therapy, chemotherapy) for metastatic breast cancer (mBC), how patients value these attributes of their medications has implications on making treatment decisions and on adherence.

To understand how patients trade off medication side effects with improved effectiveness and/or quality of life, to provide estimates of nonadherence among women with mBC, and to quantify the association of medication nonadherence with health outcomes.

The study was a cross-sectional, Internet-based survey of 181 women diagnosed with mBC who were recruited from cancer-specific online panels (response rate, 7%). Treatment information, demographics, nonadherent behaviors, and quality of life assessed by the Functional Assessment of Cancer Therapy-Breast (FACT-B) were collected in the survey, and each respondent completed a choice-based conjoint exercise to assess patient preferences. The patients' preferences were analyzed using hierarchical Bayesian logistic regression models, and the association between the number of nonadherent behaviors and the health outcomes was analyzed using general linear models.

The mean age of the patient sample was 52.2 years (standard deviation, ±9.1), with 93.9% of participants being non-Hispanic white. Results from the conjoint model indicated that effectiveness (overall survival) was of primary importance to patients, followed by side effects-notably alopecia, fatigue, neutropenia, motor neuropathy, and nausea/vomiting-and finally, dosing regimen. In all, 34.8% of survey respondents either discontinued their treatment or were nonadherent to their treatment regimen. Among those who have ever used oral chemotherapy (N = 95; 52.5%) and those currently using oral chemotherapy (N = 44; 24.3%), the number of nonadherent behaviors was significantly associated with a decrease in functional well-being (b [unstandardized regression coefficient] = -2.01 for patients who had ever used a targeted therapy and b = -3.14 for current users of a targeted therapy), FACT-General total score (b = -4.30 and b = -7.37, respectively), FACT-B total score (b = -3.93 and b = -6.11, respectively), and FACT trial outcome index (b = -5.22 and b = -8.63, respectively; all P <.05).

Patients were willing to accept substantial additional risks from side effects for gains in overall survival. Approximately 33% of women with mBC reported engaging in nonadherent behaviors. Because forgetfulness and adverse events were among the most frequent reasons for nonadherence, these results suggest that less complex treatment regimens, as well as regimens with less toxic profiles, may be associated with improvements in adherence and, subsequently, could correspond to perceptible patient benefits.