Risk factors of local recurrence after surgery in extraabdominal desmoid‐type fibromatosis: A multicenter study in Japan

This study was undertaken to clarify the risk factors, including the mutation status of CTNNB1, for the local recurrence after surgery of the rare disease desmoid‐type fibromatosis. It was designed as a multiinstitutional joint research project with 7 major centers in Japan participating. The committee members of 7 major medical centers specializing in bone and soft tissue tumors formed this study group to develop clinical care guidelines. Of 196 cases with specimens and medical records collected from the 7 institutions, 88 surgically treated ones were analyzed regarding clinicopathologic prognostic factors including CTNNB1 mutation status. Excluding R2 cases (n = 3), 5‐year local recurrence‐free survival (LRFS) was 52.9%. No case had received pre‐ or postoperative radiotherapy. Univariate analysis revealed that extremity location (P