Non-melanoma skin cancer in childhood cancer survivors previously treated with radiotherapy: Clinical findings, histology, and management.

Abstract

131 Background: Radiotherapy is a well-known risk factor for non-melanoma skin cancer (NMSC), but whether diagnosis, histologic features, or natural history of NMSC after radiotherapy resemble those observed in the general population is unknown. This study aims to describe clinical findings, histology, and management of NMSC on the skin of childhood cancer survivors previously treated with radiotherapy. Methods: A retrospective chart review (2000-2017) was performed including adult survivors of childhood cancer referred to the Adult Long-Term Follow-Up Program or the dermatology service at Memorial Sloan Kettering Cancer Center. Data was obtained from electronic medical records, including demographics, histologic subtype and treatment received for NMSC (basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)). Clinical features were assessed with clinical images. Results: 960 (mean age 40 years, SD ± 13) patients were assessed for the diagnosis of BCC/SCC after radiotherapy for cancer. The mean age of cancer diagnosis was 15 years (range: birth-39 years). The most common primary diagnosis was Hodgkin lymphoma. 82 patients developed NMSC; 67 of these developed NMSC in the field of prior radiotherapy. 283 in-field lesions were counted, of which 275 were BCC and 8 were SCC. Of the 275 BCC, 261 (95%) were primary lesions and 14 (5%) were recurrent lesions. All SCC were primary lesions. Based on clinical images, 30% of BCC were clinically pigmented; the most common presentation was macule (46%). The mean intervals for BCC and SCC from time of radiotherapy to diagnosis of the first in-field lesion were 24 years (range, 2-44 years) and 32 years (range, 14-46 years), respectively. Histologically, superficial subtype was most prevalent in the BCC subgroup, comprising 47% of all cases. Mohs surgery was the most common therapy (43% of BCC cases; 37% of SCC cases). Conclusions: Among survivors of childhood and young adult cancer, BCC was the most prevalent NMSC. Most of BCC arising in sites of prior radiotherapy for cancer treatment were of low-risk histologic subtype and had low rates of recurrence. An expanded role for topical therapy may be appropriate, but further research is needed.