Purpose: To determine how many breast cancer patients who initiated adjuvant endocrine therapy discontinued early and to evaluate adherence in patients who persisted with therapy. Secondary objectives were to explore possible trends to see if certain factors may correlate to early discontinuation of therapy.
Methods: A retrospective review of charts and pharmacy dispensing records was conducted, including patients who initiated adjuvant endocrine therapy for breast cancer at the Cross Cancer Institute from 1 January to 31 December, 2006.
Results: Out of 346 patients, 81 (22%) discontinued therapy within 2 years. Adherence rates calculated for the 265 patients who remained on therapy beyond 2 years showed that 247 (93%) of these patients had 80% or better adherence. Patients who did not undergo chemotherapy and patients with Cross Cancer Institute follow-up times of less than 1 year were significantly more likely to discontinue therapy early.
Conclusions: The majority of patients who were prescribed adjuvant endocrine therapy for breast cancer at the Cross Cancer Institute remained on therapy for at least 2 years and were adherent. Longer follow-up by Cross Cancer Institute practitioners may help decrease discontinuation rates.
Keywords: Adherence; aromatase inhibitors; breast cancer; endocrine therapy; tamoxifen.