Background The breast cancer mortality rate is high among Brazilian women, a fact probably related to late diagnosis of this condition. Adjuvant endocrine treatment with tamoxifen for 5 years can increase the survival rate of patients with hormone receptor-positive tumours. Because it is an orally administered drug, the patient plays an important role in compliance with the correct treatment (adherence) assuming much of the responsibility for her treatment. Therefore, Pharmaceutical Care has subsidies to influence treatment of these patients, identifying, preventing and resolving drug treatment problems (DTPs).

Purpose To evaluate adherence to tamoxifen and to identify the most important DTPs in patients with breast cancer on adjuvant endocrine treatment.

Materials and Methods A prospective study was conducted in a university hospital specialising in women’s health. Over 6 months patients with breast cancer were included if they were on adjuvant endocrine treatment for at least 1 month. All were interviewed by the pharmacist (Minnesota model). The instrument used to evaluate adherence was the Morisky-Green test.

Results Forty-one patients were included (mean age 55.0 years; ranging from 34–78). In the first visit, the pharmacist identified 82 DTPs (mean: 2.0 ± 1.1 DTPs/patient), 63.4% related to drug safety. The adherence to oral endocrine treatment was 36.6%; according to the Morisky-Green test; among the non-adherent patients 92.3% were non-intentional (mostly by forgetting to take doses of tamoxifen). The patient’s average time on endocrine therapy was 24.9 ± 17.6 months.

Conclusions We observed that the DTPs are present in oral endocrine therapy and adherence to this treatment can be considered inappropriate. The results obtained may contribute to the development of strategies in pharmaceutical care to improve adherence to oral endocrine therapy and decrease DTPs in breast cancer patients using tamoxifen.

No conflict of interest.