Topical minoxidil has been found associated with improvements in persistent radiation-induced alopecia (pRIA) among patients treated for central nervous system or head and neck sarcomas, according to a recent study published in JAMA Dermatology.
Minoxidil is an antihypertensive vasodilator used for the treatment of male-pattern hair loss.
The new retrospective cohort study aimed to characterise pRIA in a cohort of 71 patients with primary central nervous system (CNS) tumours or head and neck sarcomas. Patient enrolment occurred between Jan. 1, 2011 and Jan. 30, 2019 at two large tertiary care hospitals and comprehensive cancer centres. Eligible participants had a median age of 27 years (range, 4-75 years). The cohort was 51% women. Other background data showed that 90% of patients had a CNS tumour while 10% had head and neck sarcoma.
Clinicians used clinical photographs of the scalp, trichoscopic images and radiotherapy treatment plans to assess clinical and trichoscopic features, the dose-response relationship of scalp radiation and reactions to topical minoxidil use.
Grade 1 alopecia was reported in 56% of the cohort. Localised alopecia occurred in 54%, while diffuse alopecia occurred in 24% and mixed patterns occurred in 22%.
Patients underwent a median scalp radiation dose of 39.6 Gy (range, 15.1-50.0).
Greater alopecia severity was more likely to occur among patients treated with a higher radiation dose (OR = 1.15; 95% CI, 1.04-1.28) and in those who underwent proton irradiation (OR = 5.7; 95% CI, 1.05-30.8; P<.001).
A dosing threshold of 36.1 Gy was determined to yield grade 2 alopecia in 50% of patients (95% CI, 33.7-39.6 Gy).
White patches were the most dominant trichoscopic features reported in the cohort, at 57%. A negative correlation was reported between hair-shaft caliber and scalp dose in 15 patients (correlation coefficient, 0.624; P=.01).
The researchers observed a significant association between hair density and scalp radiation dose (0.381; P=.16).
An 82% response rate was reported among 34 patients treated for alopecia with topical minoxidil. Among 25 patients treated with topical minoxidil who had clinical images, alopecia severity grade improved in 16%.
Hair transplantation yielded response in two patients, while one patient responded to plastic surgical reconstruction, according to the findings.
“The findings of this study suggest that topical minoxidil and procedural interventions may have benefit in the treatment of pRIA. Surgical procedures may be effective in nonresponders,” the researchers concluded.