Does signet ring cell carcinoma component signify worse outcomes for patients with colorectal cancer?

The purpose of this study was to elucidate the differences in clinical pathology and prognosis between signet ring cell carcinoma component and adenocarcinoma in colorectal cancer.

From April 2007 to December 2016, a total of 4348 patients with colorectal cancer underwent surgery, of which 3283 were included in the study. One patient was diagnosed with signet ring cell carcinoma (SRCC); 16 were diagnosed with signet ring cell carcinoma component (SRCCc); and 3266 patients were diagnosed with adenocarcinoma (ADC). We matched SRCCc and ADC with a propensity score of 1:3 and analyzed overall survival rates (OS) and cancer-specific survival rate (CSS) between the 2 groups before and after matching.

Before matching, patients in the SRCCc group had more advanced cancer (stage III-IV: 87.5% vs 45.6%; P < .001), more perineural invasion (75.0% vs 44.2%; P = .013), and higher lymphatic invasion (87.5% vs 42.4%; P < .001) than those in the ADC group. Consequently, the OS (P < .001) and CSS (P = .049) of the SRCCc group were worse than the ADC group. Peritoneal metastasis was found in 4 (57%) patients with stage IV disease. However, after tumor staging and all background factors were matched, there were no significant differences in prognosis for OS (P = .127) and CSS (P = .932) between the 2 groups.

SRCCc is more likely to be associated with lymphatic invasion and perineural infiltration than ADC, leading to significantly poorer survival outcomes. However, when all background factors are matched with ADC, the prognosis of SRCCc is not worse than ADC. Improving the treatment outcomes of peritoneal metastasis may be pivotal in the treatment of SRCCc.