Eligibility, compliance and persistence of sequential therapy with aromatase inhibitors following 2-3 years of tamoxifen in endocrine adjuvant breast cancer therapy.

Objective: This study evaluated the eligibility, compliance and persistence of sequential therapy, i.e. a switch to an aromatase inhibitor (AI) following 2-3 years of tamoxifen, in adjuvant endocrine breast cancer (BC) treatment.

Methods: Data concerning 388 BC patients (age ≤70 years) who started endocrine adjuvant therapy between 1998 and 2008 were analyzed.

Results: From the 263 patients who started therapy with tamoxifen, 167 (63.5%) were eligible for a sequential therapy. Fifty-nine patients (35.3%) were offered a switch by their physicians; women who had their follow-up at oncological units received the offer more often when compared to those treated by general practitioners (p < 0.001). Out of these 59 patients, 50 followed the proposal (compliance 84.7%). Of those who agreed to a sequential therapy, 2 (4%) were non-persistent to endocrine therapy; in 9 cases (18.0%), a re-switch to tamoxifen was done due to AI-related adverse side effects.

Conclusions: Only a minority of the patients who started an endocrine adjuvant BC therapy was eligible for sequential therapy. Patients who underwent a switch had a high rate of persistence. Efforts should be made to make sure that all physicians, above all general practitioners, who are involved in the treatment of BC patients, are provided with current therapy guidelines.