The Prognostic Role of β-Catenin Mutations in Desmoid-type Fibromatosis Undergoing Resection Only: A Meta-analysis of Individual Patient Data

Objective: This meta-analysis (PROSPERO CRD42018100653) uses individual patient data (IPD) to assess the association between recurrence and CTNNB1 mutation status in surgically treated adult desmoid-type fibromatosis (DTF) patients. Summary of Background Data: The majority of sporadic DTF tumors harbor a CTNNB1 (ss-catenin) mutation: T41A, S45F, and S45P or are wild-type (WT). Results are conflicting regarding the recurrence risk after surgery for these mutation types. Methods: A systematic literature search was performed on June 6th, 2018. IPD from eligible studies was used to analyze differences in recurrence according to CTNNB1 mutation status using Cox proportional hazards analysis. Predictive factors included: sex, age, mutation type, tumor site, tumor size, resection margin status, and cohort. The PRISMA-IPD guideline was used. Results: Seven studies, describing retrospective cohorts were included and the IPD of 329 patients were used of whom 154 (46.8%) had a T41A mutation, 66 (20.1%) a S45F mutation, and 24 (7.3%) a S45P mutation, whereas 85 (25.8%) patients had a WT CTNNB1. Eighty-three patients (25.2%) experienced recurrence. Multivariable analysis, adjusting for sex, age, and tumor site yielded a P-value of 0.011 for CTNNB1 mutation. Additional adjustment for tumor size yielded a P-value of 0.082 with hazard ratio's of 0.83 [95% confidence interval (CI) 0.48-1.42), 0.37 (95% CI 0.12-1.14), and 0.44 (95% CI 0.21-0.92) for T41A, S45P and WT DTF tumors compared to S45F DTF tumors. The effect modification between tumor size and mutation type suggests that tumor size is an important mediator for recurrence. Conclusions: Primary sporadic DTFs harboring a CTNNB1 S45F mutation have a higher risk of recurrence after surgery compared to T41A, S45P, and WT DTF, but this association seems to be mediated by tumor size.