Clinical significance of signet-ring-cell colorectal cancer as a prognostic factor

Purpose: The aim of this study is to evaluate the prognosis for patients with a signet-ring-cell carcinoma (SRCC) who undergo curative surgery by comparing them to patients with an adenocarcinoma (ADC), excluding a mucinous ADC. Methods: Between September 1994 and December 2013, 14,110 patients with colorectal cancer underwent surgery and among them, 12,631 patients were enrolled in this study. 71 patients with a SRCC and 12,570 patients with a ADC were identified. We analyzed the disease-free survival and the overall survival rates before and after a 1:2 propensity score matching and evaluated those rates after stage stratification. Results: The median follow-up durations were 48.5 months for the SRC group and 48.6 months for the ADC group. The disease-free survival rates and the overall survival rates were significantly lower in the SRC group before and after propensity score matching (P < 0.001). After stratification by stage, no differences were observed between the SRC and the ADC groups for the disease-free survival (DFS) and the overall survival (OS) rates for patients with cancer in its early stages (P = 0.913 and P = 0.380 for the DFS and the OS, respectively, in stages 0 and I, and P = 0.223 and P = 0.991 for the DFS and the OS, respectively, in stage II), but those rates were significantly lower in the SRC group for cancer in its later stages (P < 0.001, respectively in stages III and IV). Conclusion: For cancer in advanced stages, patients with a resectable colorectal SRCC had a poorer prognosis after propensity score matching than those with an ADC did. Therefore, more intensive surveillance and closer observation should be offered to such patients.