Milea Timbergen

196 Table 3. Univariable Cox proportional hazards regression model for recurrence Univariable analysis a Variable n HR (95% CI) p-value Sex 0.290 Female 247 1.00 (reference) - Men 82 1.31 (0.80-2.14) 0.290 Age 288 0.99 (0.97-1.01) 0.190 Mutation type 0.006 S45F 66 1.00 (reference) - T41A 154 0.64 (0.39-1.06) 0.081 S45P 24 0.30 (0.10-0.86) 0.026 WT 85 0.34 (0.17-0.68) 0.002 Tumour site <0.001 Trunk/back 194 1.00 (reference) - Head/neck 9 2.53 (0.54-11.8) 0.236 Extremity 77 3.81 (1.98-7.35) <0.001 EA NS 49 2.70 (1.33-5.46) 0.006 Tumour size in mm b 283 1.69 (1.16-2.47) 0.007 Resection margin status 0.170 - R0 185 1.00 (reference) R1 126 1.38 (0.87-2.18) 0.170 HR, hazard ratio; CI, confidence interval; WT, wild-type; EA NS, extra-abdominal not specified a Cohort was used as a stratification variable due to a violation of the proportional hazards assumption (p = 0.019) b Used as a log transformed value Tumour size Despite the fact that none of the included studies described tumour size as a prognostic factor, a significant p-value for tumour size (log-transformed) was found in the univariable analysis. To gain more insight into this variable, we tested with an analysis of variance whether there were differences in tumour size (as a log transformed variable) between the cohorts and we found a statistically significant difference (p < 0.001). The cohort from Van Broekhoven et al. and Mussi et al. contained smaller tumours. Next, we investigated whether the tumour sizes differed between the various mutation groups and found a statistically significant difference (p = 0.001) in tumour size between mutation groups. From this analysis we concluded that tumours harbouring a S45F and S45P mutation were larger compared to T41A and WT tumours. Additionally, we looked whether the tumour size differed between the tumour sites, but this difference was not statistically significant (p = 0.392). No significant association could be found between tumour site and CTNNB1 mutation type (p = 0.261), and between mutation type and sex (p = 0.643), using the chi- 7