Topical minoxidil, procedural interventions may benefit radiation-induced alopecia

Topical minoxidil and procedural interventions were associated with improvements in persistent radiation-induced alopecia among patients treated for central nervous system or head and neck sarcomas, according to recent findings.

“Persistent radiation-induced alopecia (pRIA) and its management have not been systematically described,” Gregory S. Phillips, BS, of the dermatology service in the department of medicine at Memorial Sloan Kettering Cancer Center, in New York, and colleagues, wrote.

In the current retrospective cohort study, the researchers aimed to characterize pRIA in a cohort of 71 patients with primary central nervous system (CNS) tumors or head and neck sarcomas. Patient accrual occurred between Jan. 1, 2011 and Jan. 30, 2019 at two large tertiary care hospitals and comprehensive cancer centers.

Eligible participants had a media age of 27 years (range, 4-75 years). The cohort was 51% women. Other background data showed that 90% of patients had a CNS tumor 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. Localized alopecia occurred in 54%, while diffuse 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,” the researchers concluded.