University Hospital Birmingham 9 (3.2) 67 (5.8) University Hospitals Gasthuisberg Leuven 11 (3.9) 53 (4.6) University of Ottawa 9 (3.2) 33 (2.9) Veneto Institute of Oncology 2 (0.7) 13 (1.1) Yale University 3 (1.1) 8 (0.7) Total 280 1114 RPS, retroperitoneal sarcoma Distal Pancreatectomy for Retroperitoneal Sarcoma

Objective In this study, we aimed to describe the clinical features, management, and outcomes of desmoid tumors (DTs) in familial adenomatous polyposis (FAP) patients at a high-volume sarcoma center. Methods Consecutive patients with FAP and DTs were identified from our institutional databases (1985–2021). Patient demographics, treatment, and outcomes were described. Categorical data were compared using Fisher’s exact test, and Kaplan–Meier curves were used to estimate progression-free survival (PFS). Results Forty-five patients with 67 DTs were identified: 39 mesenteric or retroperitoneal (58.2%), 17 abdominal wall (25.4%), 4 extremity (6%), 4 breast (6%) and 3 back (4.4%). Severe DT symptoms were present in 12 patients (26.7%). Initial treatments per tumor were observation in 30 (44.8%) DTs, chemotherapy in 15 (22.4%) DTs, surgery in 10 (14.9%) DTs, and other systemic therapies in 10 (14.9%) DTs. The majority of DTs remained stable with observation or a single intervention (77.8%). Median PFS was 23.4 years (95% confidence interval 7.6–39.2). In the 12 severely symptomatic patients, four patients required more than two interventions for DT control. At a median follow-up of 6.0 years (range 0.7–35.8 years), 33 (73.3%) patients were alive with disease, 7 (15.6%) were alive without disease, and 5 (11.1%) died of other causes. No patients died of DT-related complications. Conclusions The majority of DTs in FAP patients remained stable with observation or a single intervention. There were no DT-related deaths; however, 12 of 45 patients (26.7%) experienced significant tumor morbidity and required more interventions for disease control. Further studies on quality of life are required. Supplementary Information The online version contains supplementary material available at 10.1245/s10434-023-13675-1.

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