Risk of subsequent primary malignancies after dermatofibrosarcoma protuberans diagnosis: A national study

Background: Patients frequently live many years after diagnosis of dermatofibrosarcoma protuberans (DFSP). Objective: We sought to determine the risk of subsequent primary malignancy (SPM) after DFSP diagnosis. Methods: Using the Surveillance, Epidemiology, and End Results database (1973-2008) for 3734 patients with DFSP, we compared the risk of developing 14 SPMs (12 most prevalent cancers in the United States plus other nonepithelial and soft tissue) relative to risk in the general population of same sex, race, and age and year of diagnosis. Results: Patients given the diagnosis of DFSP had an overall increased risk of SPM (observed:expected [O:E], 1.20; 95% confidence intervals [CI], 1.04-1.39), with much of the overall increased risk attributable to increased risk of nonepithelial skin cancer (O:E, 9.94; 95% CI, 3.38-22.30). Specifically, female patients with DFSP were at increased risk of other nonepithelial skin cancer (O:E, 14.50; 95% CI, 3.46-38.98), melanoma (O:E, 2.59; 95% CI, 1.02-5.35), and breast cancer (O:E, 1.44; 95% CI, 1.00-2.00). Male patients were not at increased overall risk (O:E, 1.18; 95% CI, 0.96-1.44) of SPM or at increased risk of any specific malignancy (P > .05) adjusted for multiplicity of t tests. Limitations: Surveillance bias may have led to increased rates and earlier detection of primary malignances in patients with DFSP compared with the general population. Individual data that may reveal shared environmental causes of DFSP and SPM were unavailable. Conclusions: Patients with DFSP are at increased risk of a number of SPMs. (J Am Acad Dermatol 2013;68:790-6.)