Oral minoxidil for the treatment of late alopecia in cancer survivors

12022 Background: Late alopecia is defined as incomplete hair regrowth > 6 months following cytotoxic chemotherapy or from initiation of endocrine therapy. It has been reported in up to 25-30% of cancer survivors and is associated with decreased quality of life and reduced dose intensity of cancer therapies. Minoxidil is an aminopyridine potassium channel opener, resulting in vasodilation and premature entry of resting hair follicles into the anagen (growth) phase and increase in hair follicle size. This study aims to assess clinical outcomes and adverse events of oral minoxidil for the treatment of cancer therapy-related late alopecia. Methods: We retrospectively assessed all women with late alopecia treated with oral minoxidil (1.25 mg daily) evaluated at an oncodermatology referral program between 1/2018-5/2021. Outcomes were assessed by standardized photography (4 views) and trichoscopy (HairMetrix, Canfield Scientific, Inc.). Trichoscopy recorded hair density (hair count/cm2) and hair thickness (shaft diameter) at uniform frontal and occipital target areas (12 and 36 cm midline from the glabella, respectively). Adverse events were recorded and graded using CTCAE v5.0. Descriptive statistics were used to summarize the patient demographics and clinical characteristics. Changes in trichoscopy measurements from baseline to follow-up were estimated using paired t-tests. Results: Two hundred and sixteen patients (mean age 57.8±13.7) were included for analysis. Thirty-one (14%) received chemotherapy alone, 65 (30%) endocrine monotherapy, and 120 (56%) chemotherapy followed by endocrine therapy. The majority of patients (n = 170, 79.1%) had a history of breast cancer. Standardized photography assessments (n = 119) after a median of 105 days (IQR = 70) on oral minoxidil revealed clinical improvement in 88 (74%). Trichoscopy assessments (n = 42) after a median of 91 days (IQR = 126) demonstrated increased frontal hair density (124.2 vs 153.2 hairs/cm2, p = 0.008) and occipital hair density (100.3 vs 123.5 hairs/cm2, p = 0.004). There was no statistically significant difference in average frontal or occipital hair thickness (69.3 vs 67.3 μm, p = 0.22, and 70.3 vs 69.9 μm, p = 0.84, respectively). No patients reported discontinuation of oral minoxidil due to adverse effects. Conclusions: Oral minoxidil may benefit both frontal and occipital late alopecia in cancer survivors treated with cytotoxic and/or endocrine therapy. This regimen was well tolerated by patients. Prospective, controlled studies are needed to confirm these observations.