P137 Survival of dermatofibrosarcoma protuberans after Mohs micrographic surgery vs. wide local excision in the USA

Abstract Dermatofibrosarcoma protuberans (DFSP) is a rare, malignant skin cancer commonly found on the trunk. DFSP includes primary DFSP and Bednar tumour, a pigmented, intermediate-grade subtype of primary DFSP that has an increased tendency for local invasion and secondary recurrence. DFSP can be surgically resected with Mohs micrographic surgery (MMS) or wide local excision (WLE). Despite MMS being considered the ‘gold standard’ for the treatment of several malignant skin cancers, WLE is frequently used to treat DFSP, and the difference in outcomes has not been well explored. To fill in this literature gap, data from the National Cancer Database were analysed to explore survival based on surgical modality. A retrospective cohort study of 8878 patients diagnosed with primary DFSP (8699) and Bednar tumours (179) between 2004 and 2021 was conducted across 1500 Commission on Cancer facilities located in 49 US states and Puerto Rico. The impact of surgical treatment type on survival was analysed by Kaplan–Meier survival analysis. Other demographic factors, such as age, sex, race and comorbidity were considered to determine any trends in our cohort. In total, 5090 patients with DFSP had survival data based on surgery type, with 805 undergoing MMS and 4285 undergoing WLE. Overall, 53.7% of patients were female. With respect to race, 70.3% of patients were White, 21.7% Black, 4.3% Asian and 3.7% other. The average age of our cohort was 43.2 years (SD 15.7, range 0–90). Lastly, > 90% of the patients had a Charlson–Deyo comorbidity score of zero and were relatively healthy. MMS was associated with significantly increased survival compared with WLE (P = 0.012), with patients living approximately 6 months longer than those treated with WLE (210 months vs. 204 months, respectively). While the standard of practice for DFSP is general surgical excision, including WLE, this study supports MMS as the preferred treatment based on improved survival outcomes. Although there are many factors that may require non-MMS surgery, these results highlight the importance of increased access to a variety of surgical treatment options for all patients. Furthermore, they emphasize the need for more clinical data on DFSP to better equip physicians to diagnose and treat this rare but dangerous skin cancer. Especially in comparison with the average age of skin cancer diagnosis at 70 years, six additional months of survival becomes increasingly important for the young and healthy patient population affected by DFSP.