SMAD4 and colorectal carcinoma: Comparing SMAD4 mutant patients with SMAD4 wild-type patients in CRC, the summary HR for PFS/RFS was 1.59 (95% CI 1.14–2.22, P = 0.006) (Fig. 2b) and there was moderate heterogeneity between the studies (I2 = 48.2%, P heterogeneity = 0.145), so we use the fixed-effect model to pool HR.