Prognosis of three histological subtypes of colorectal adenocarcinoma: A retrospective analysis of 8005 Chinese patients

Background and objectives To evaluate the effect of the varied histological subtypes on clinical outcomes and to determine the prognostic implications of mucinous adenocarcinomas (MAC) and signet ring cell carcinomas (SRCC) compared with classic adenocarcinomas (AC). Methods A total of 8005 patients, including 7502 AC, 428 MAC and 75 SRCC, who underwent definitive surgery between 2007 and 2015 at Fudan University Shanghai Cancer Center were remained for analysis in this study. Results MAC and SRCC were more common in right‐sided colon cancer, in males and in young patients, compared to AC; moreover, MAC and SRCC led to a higher probability to develop lymph node metastasis, lymphovascular invasion and perineural invasion. For survival outcomes, we found that the 5‐year overall survival (OS) of SRCC was significantly lower than that of MAC and AC, while the 5‐year OS of MAC is much lower than that of AC. However, in multivariable analysis, the difference in survival between SRCC, MAC and AC was no longer significant, especially when stratified by N stage. Conclusions MAC and SRCC are rare subtypes of colorectal cancer with a higher T stage, N stage as well as higher incidence of lymphovascular and nerve invasion. However, neither MAC nor SRCC was an independent predictor of decreased survival in multivariate analysis. Our study sought to evaluate the effect of the varied histological subtypes on clinical outcome with the aim of determining the clinical significance of three different histological subtypes of colorectal adenocarcinoma in prognosis by investigating 8005 Chinese cases enrolled in this retrospective study. We found that MAC and SRCC are rare subtypes of colorectal cancer with a higher T stage, N stage as well as higher incidence of lymphovascular and nerve invasion; however, in multivariable analysis, the difference in survival between SRCC, MAC, and AC was no longer significant, especially when stratified by N stage.