Health disparities in narrowband UVB phototherapy for mycosis fungoides: A multi-institutional cohort study across Fitzpatrick skin types.

Abstract

Mycosis fungoides (MF) is associated with poorer outcomes in patients with skin of color, yet evidence guiding narrowband UVB (NB-UVB) therapy in higher Fitzpatrick skin types (FSTs) remains limited. To evaluate NB-UVB response across FST groups in a multi-institutional MF cohort. Retrospective cohort study of MF patients treated with NB-UVB monotherapy at Columbia, Emory, and Johns Hopkins (2010-2025). Primary outcomes were percent change in total body surface area involvement and complete/partial response (CR/PR) rates. Among 114 patients (63 FST I-III; 51 FST IV-VI), FST IV-VI were younger and more frequently had hypopigmented MF. FST I-III patient achieved greater total body surface area reduction (-73% vs -35% at mid-year; -78% vs -26% at year-end) and higher CR/PR rates, with differences persisting after multivariable adjustment. Rapid response (complete or partial response within ≤4 months) occurred more often in FST I-III (53% vs 34%), while nonresponse was more frequent in FST IV-VI (39% vs 16%). Mixed-effects models confirmed both groups improved over time, but FST I-III demonstrated significantly greater total body surface area reduction at multiple timepoints. Retrospective design; modest sample size. NB-UVB benefits all FSTs but yields earlier and more complete clearance in FST I-III. Prospective studies are warranted to guide individualized treatment strategies.