Treatment of Cutaneous Adnexal Carcinoma With Radiotherapy: A 20-Year, Single-Institution Experience in 49 Patients

Cutaneous adnexal carcinomas (CACs) are rare skin cancers with no established treatment guidelines. Given the limited data, this study aims to explore the characteristics and outcomes of patients with CAC treated with radiation therapy (RT).

Patients diagnosed with CAC between 2000 and 2020 who received RT were included. Kaplan-Meier methods measured time to local recurrence (LR), regional recurrence (RR), locoregional recurrence (LRR), distant metastasis (DM), and progression-free survival (PFS). Fisher exact test compared frequency distributions.

Forty-nine patients with an average age of 65 years were studied. Most were White males with head and neck tumors. Common subtypes were adnexal adenocarcinoma, sebaceous carcinoma, and microcystic adnexal carcinoma. Patients received RT diagnosis or recurrence. The median overall survival was 44 months, with a median follow-up of 41 months for surviving patients. For patients with de novo cancer treated with surgery and adjuvant RT (n=22), 2-year PFS, LR, RR, LRR, DM, and OS were 77%, 5%, 0%, 5%, 10%, and 95%, respectively, with all LRR occurring outside the irradiated area. Patients with de novo cancer who received definitive RT (n=9) experienced 2-year PFS, LR, RR, LRR, DM, and OS of 30%, 46%, 13%, 55%, 40%, and 67%, respectively, with all LRR events occurring within the irradiated area. LR within the irradiated volume was associated with immunosuppression (95% CI: 19-99). Patients treated at recurrence had inferior outcomes.

Surgical resection and adjuvant RT effectively control CAC, while definitive RT shows lower disease control. Novel strategies are needed to improve outcomes in patients receiving definitive RT.