Topical Minoxidil, Procedural Interventions May Benefit Persistent Radiation-Induced Alopecia

Findings published in JAMA Dermatology suggest the possible utility of topical minoxidil, hair transplantation, and plastic surgical reconstruction in the treatment of persistent radiation-induced alopecia (pRIA) for patients with primary central nervous system (CNS) tumors or head and neck sarcomas.

“These findings may inform pretherapy counseling and efforts to identify preventive and therapeutic strategies, including randomized clinical trials in cancer survivors, for this burdensome sequela of a principal axis of cancer therapy,” the authors wrote.

In this retrospective cohort study, researchers evaluated 71 children and adults diagnosed with primary CNS tumors or head and neck sarcomas from 2 large tertiary care hospitals and comprehensive cancer centers. Of those included in the study, 64 (90%) had a CNS tumor and 7 (10%) had head and neck sarcoma.

Overall, alopecia severity was grade 1 in 40 of 70 patients (56%), with localized (29 of 54 [54%]), diffuse (13 of 54 [24%]), or mixed (12 of 54 [22%]) patterns. Further, the median (range) estimated scalp radiation dose was found to be 39.6 (15.1-50.0) Gy, with a higher dose (OR, 1.15; 95% CI, 1.04-1.28) and proton irradiation (OR, 5.7; 95% CI, 1.05-30.8) associated with greater alopecia severity (P < .001). In addition, the dose at which 50% of patients were estimated to have severe or grade 2 alopecia was 36.1 Gy (95% CI, 33.7-39.6 Gy).

“Our estimation of maximum scalp dose was limited in part because it did not directly consider the radiation field volume and involved scalp surface area; however, point approximation of scalp surface dose may be a convenient metric for use during treatment planning,” the authors explained.

Trichoscopic findings were analyzed in 28 of 71 patients (39%). The predominant trichoscopic features observed included white patches (57%), thin arborizing vessels (36%), and milky red areas (32%). Additionally, hair caliber was negatively correlated with the estimated scalp radiation dose in 15 patients with trichoscopy and radiotherapy treatment plans (Spearman correlation coefficient ρ = -0.624; P = .01). Ultimately though, the association between hair density and scalp radiation dose was not statistically significant (ρ = -0.381, P = .16).

“Larger, prospective studies would be better suited to deciphering the potential relevance of trichoscopy to pRIA prognosis and treatment allocation,” the authors noted.

Further, topical minoxidil, 5%, solution was prescribed to 53 patients (75%). In total, 28 of 34 evaluable patients (82%) responded to minoxidil treatment, with a median follow-up time of 61 weeks (95% CI, 41-97; IQR, 21-105; range, 7-226 weeks). Among 25 recipients of minoxidil with clinical images available, complete response occurred in 4 patients (16%), partial response in 13 patients (52%), stable alopecia in 7 patients (28%), and progression of alopecia in 1 patient (4%). In addition, 3 patients (4%) underwent a procedural intervention for pRIA, including 2 patients who received hair transplantation with partial and complete responses and 1 patient who underwent scalp expansion and plastic surgical reconstruction with a complete response.

“These findings suggest that topical minoxidil could have benefit in pRIA and that clinical trials are warranted to determine efficacy and tolerability for pRIA in cancer survivors,” the authors wrote.

Importantly, the researchers indicated that the retrospective study design and limited availability and analysis of radiotherapy treatment plans, standardized clinical photographs, and trichoscopy images were limitations of this study.

Reference:

Phillips GS, Freret ME, Friedman DN, et al. Assessment and Treatment Outcomes of Persistent Radiation-Induced Alopecia in Patients With Cancer. JAMA Dermatology. doi: 10.1001/jamadermatol.2020.2127