|| Checking for direct PDF access through Ovid
To compare metastatic patterns, survival and local recurrence rates between signet-ring cell (SC) and non-signet cell mucinous carcinomas (MC) of the colon and rectum to non-mucinous adenocarcinomas (NMC).A literature search of Medline, Embase, Ovid and Cochrane Library was performed to identify comparative studies investigating the outcomes between SC, MC versus NMC. Random and fixed-effects meta-analytical models were used. Hazard ratios (HR) were used to assess survival. Odds ratios (OR) were used to compare the patterns of metastatic disease and local recurrence.Twenty-three studies were included reporting on 1945 patients with SC, 19 624 with MC and 173 546 with NMC. Five-year survival was significantly worse for SC compared to NMC (HR = 2.13; P < 0.0001) and MC to NMC (HR = 1.24; P = 0.01) group. Haematogenous metastases occurred less frequently in patients with SC (OR = 0.40; P = 0.01) and MC (OR = 0.58; P = 0.0005). However peritoneal metastases were more frequently observed in SC (OR = 4.81; P < 0.000001) and MC (OR = 3.74; P = 0.003). In stage III disease, 5-year locoregional recurrence rates were higher for SC (OR = 15.29; P = 0.04) but not for MC (OR = 2.64; P = 0.35) compared to NMC.This study suggests a poorerprognosis for SC, with high likelihood of locoregional recurrence compared to NMC. SC and MCpredominantly metastasise peritonealy/transcolemicaly whereas NMC showed apropensity for haematogenous spread. These findings may impact the surgical and oncological management of colorectal cancer, depending on histopathological characteristics.