Signet ring cell carcinoma as a potential confounding factor in the analysis of outcomes with colorectal mucinous adenocarcinoma

Abstract

Correspondence: We read with keen interest the article titled ‘Mucinous adenocarcinomas: poor prognosis in metastatic colorectal cancer’ by Mekenkamp et al. published in the European Journal of Cancer (March 2012). We noted that the investigators have never mentioned in the entire course of their article as to whether any attempts were made to differentiate between ‘mucinous adenocarcinomas’ from ‘signet ring cell carcinomas’ during case inclusion into the study analysis. This is of vital importance, since including the signet ring cell carcinomas amongst mucinous carcinomas can alter interpretations of outcomes, given that signet ring cell carcinomas are already known to be associated with worse prognosis. Though the authors have mentioned that tumours were considered as ‘mucinous adenocarcinoma’ if >50% of their volume consisted of ‘mucin’, they have not mentioned about the specific compartment of the ‘mucin’as to it being extracellular or intracellular in accumulation. There has never been a clear boundary of demarcation between the domains of mucinous adenocarcinomas and signet ring carcinomas, with either type often being confused for the other. Though both mucinous and signet ring carcinomas are associated with an increased mucinous component, the mucinous adeno-