31412 Response and local control in patients treated with low-dose radiotherapy for tumoral mycosis fungoides

Abstract

Background: Mycosis fungoides (MF) is often characterized by patches or plaques that may progress into tumoral lesions (TLs). Low-dose radiotherapy (LDRT) is an effective option for local palliation, but little evidence exists regarding its efficacy for TLs. Methods: 73 lesions in 18 patients treated with LDRT (8 Gy in 2 fractions) for MF between 2013-2020 were analyzed. Response was determined at first follow-up and defined as: complete response (CR),; partial response (PR), ≥50% reduction; no response (NR), <50% reduction. Results: Median age was 68 years and 64% of lesions were on the extremities. 25 lesions were tumoral and 48 were nontumoral. A greater proportion of African American individuals were observed in the TL group (52% v. 25%). Five lesions (all TL) had biopsy-confirmed large cell transformation. Median follow-up was 9.3 months. Overall CR/PR rate was 93.2% (97.9% nonTL v. 84% TL, P = .04). In the non-TL versus TL groups, CR was observed in 16.7% v. 4.0%, PR in 81.2% v. 80.0%, NR in 2.1% v. 16.0%, respectively. Local progression occurred in 6/25 TL and 0/48 non-TL. Local control at 6-, 12-, and 24-months was 100% for non-TLs compared with 86.6%, 80.8%, and 60.6% for TLs (P < .01). Median time-to-progression was 5.5 months. Conclusion: LDRT offers clinically meaningful response and durability of palliation in most patients with tumoral MF, despite lower response rates and worse local control. This may represent a reasonable option for palliation of tumoral lesions for patients in whom the risk/benefit profile is acceptable.