Endocrine therapy-induced alopecia (EIA) has been anecdotally reported but not systematically described.

To characterize EIA in patients with breast cancer.

Retrospective cohort study of 112 patients with breast cancer, diagnosed with EIA from January 1, 2009, to December 31, 2016, the patients were examined at the dermatology service in a large tertiary care hospital and comprehensive cancer center.

The clinical features, alopecia-related quality of life (QoL), and response to minoxidil of EIA in patients with breast cancer were assessed. Data from the Hairdex Questionnaire was used to assess the impact of the alopecia on patients QoL. Higher score indicates lower QoL (0-100 score). Efficacy of minoxidil was measured at 3 or 6 months by a single-blinded investigator through standardized clinical photographs of the scalp.

A total of 112 female patients with breast cancer were included (median [range] age, 60 [34-90] years). A total of 104 patients (93%) had standardized clinical photographs; of these, 59 patients (53%) had trichoscopy images available at baseline, and 46 patients (41%) were assessed for response to minoxidil. Alopecia was attributed to aromatase inhibitors in 75 patients (67%) and tamoxifen in 37 (33%). Severity was grade 1 in 96 of 104 patients (92%), and the pattern was similar to androgenetic alopecia. The predominant trichoscopic feature at baseline was the presence of vellus hairs and intermediate- and thick-diameter terminal hair shafts. A negative impact on QoL was reported, with a higher effect in the emotion domain according to the Hairdex score (mean [SD], 41.8 [21.3]; P < .001). After treatment with topical minoxidil, moderate or significant improvement in alopecia was observed in 37 of 46 patients (80%).

Endocrine therapies are associated with a pattern alopecia similar to androgenetic-type, consistent with the mechanism of action of causal agents. A significant negative impact on QoL was reported by patients, despite mostly mild alopecia severity.