Adherence to Hormonal Therapy in Breast Cancer Patients in Saudi Arabia: A Single-Center Study

Breast cancer is one of the most common types of cancer in women. Approximately three-quarters of all breast cancer patients have estrogen and/or progesterone receptor positivity. As a result, the majority of patients receive hormonal treatment for between five and 10 years. Long-term use of hormonal therapy reduces the recurrence rate and the risk of death. In Saudi patients, adherence to hormonal therapy is not adequately assessed. The primary objective of this study is to determine the clinical outcomes associated with hormonal therapy adherence in breast cancer patients. This is a retrospective cohort study of patients who received adjuvant hormonal therapy for hormone-receptor-positive breast cancer. Patients were included if they had received at least two prescription refills following their breast cancer diagnosis. The primary outcome measure was mortality and disease progression in relation to hormonal therapy adherence. Progression of disease is defined as local recurrence or radiographic evidence of metastatic disease. The secondary outcome measure was the study population's adherence to hormonal therapy. The proportion of days covered during hormonal therapy was used to assess adherence (PDC). PDC was calculated as the number of days in the prescription period divided by the total number of days in the prescription period. Patients are considered adherent if their PDC value is greater than 0.8. The mortality and disease progression curves were generated using the Kaplan-Meier method. The proportion of patients adhering to hormonal therapy was determined using descriptive analysis. The IRB granted approval. A total of 121 patients were included in the study from the 380 patients screened. Tamoxifen, letrozole, and anastrozole were administered to 58%, 27%, and 14% of patients, respectively. The median age was 53 years. Women who were postmenopausal constituted 52.3% of the study population. The majority of patients were in Stages II and I (56.2% and 16.53%, respectively). The majority of the tumors were Grade II (58.68 %). Adherence was not associated with disease progression (HR, 0.66; 95% CI, 0.25-1.72) or mortality (HR, 1.391; 95 percent CI, 0.33-5.82). Disease progression and mortality were not found to be significantly associated with hormonal therapy adherence in this study. A larger study is required to confirm the findings of our study.