Persistence and discontinuation of adjuvant endocrine therapy in women with breast cancer

Although 8-73 % of breast cancer patients who receive adjuvant endocrine therapy discontinue it, discontinuation is little studied in Asian breast cancer patients. To determine frequency and reasons for discontinuation at a single institution, we reviewed records and database information for women with hormone receptor-positive breast cancer who were treated at the National Kyushu Cancer Center 2001-2006, defining "persistence" as continued endocrine treatment (even when physicians decided to stop because of recurrent disease or severe adverse effects), and "discontinuation" as ending therapy due to patient's wishes. Among 686 patients who started adjuvant endocrine therapy, 607 patients (88 %) persisted, 79 patients (12 %) discontinued. Of the 79 patients who discontinued, 37 (46 %) did so because of side effects, 26 (33 %) stopped appointments, 11 (14 %) stopped for "no particular reason", 4 (5 %) to get pregnant, and 1 (1 %) for economic reasons. The rate of persistence was higher in patients with lymph node involvement than in those without lymph node involvement (92 vs. 87 %; P = 0.03). Clinicians should discuss side effects with patients, both as part of informed consent and to prepare them to continue therapy, and should be aware that over time, patients' reasons for discontinuation change.