Milea Timbergen

188 tumours 19, 22-24 . However, others report conflicting results and could not reveal an impact of specific CTNNB1 mutations on outcome 20, 25 . These contradictory results are almost certainly due to the fact that these are relatively small retrospective studies including heterogeneous patient cohorts, which hinders the assessment of the true prognostic value of specific CTNNB1 mutations on outcome. Because the insight into prognostic factors can be crucial to come to a more personalized treatment approach for DTF patients who undergo a resection, we performed a meta-analysis using individual patient data (IPD) to study the impact of the CTNNB1 mutation on the risk of local recurrence in a large series of sporadic DTF patients. The hypothesis is that S45F mutated DTF tumours have a higher risk of local recurrence than WT or other CTNNB1- mutated DTF tumours. The objective of this meta-analysis with IPD is to evaluate the impact of the CTNNB1 mutation type on recurrence and recurrence-free survival (RFS) in adult patients with primary DTF tumours undergoing surgical resection alone. Materials and methods Protocol and registration This study was approved by the local Medical Ethics Committee of the Erasmus Medical Center (MC) (MEC-2018-1386) Rotterdam, the Netherlands. The protocol of this meta- analysis was registered on PROSPERO (CRD42018100653) and can be accessed at www. crd.york.ac.uk/PROSPERO 26 . Information sources A systematic literature search was performed by an Erasmus MC librarian expert on June 6 th , 2018. The following databases were used for the search: Embase.com, Medline Ovid, Web of science, Cochrane Central, Psych INFO Ovid and Google Scholar. Duplicated records were removed. No data or language filters were applied. The search strategy is provided in Supplemental Table 1. Eligibility criteria Studies with surgically treated sporadic DTF as a main subject were included. Papers describing follow-up, risk of recurrence, or recurrence-free survival (RFS) in primary DTF tumours with known CTNNB1 mutational type were included for this meta-analysis. The flowchart depicting the study selection procedure is available in Supplemental Table 2. 7