The Effect of the Mucinous Component Presence on the Clinical Outcomes of Colorectal Cancer

Background. The effect of colorectal cancer (CRC) histological subtypes on the prognosis is still a controversial issue. We aimed to compare clinical findings, histopathologic data, and survival outcomes in CRC patients with classical and mucinous subtypes. 
Methods. Patients who were operated on for CRC between 2010 and 2017 were included in the study. Patients were classified into two groups according to the presence of a mucinous component: mucinous adenocarcinoma (MAC) - mucinous component > 50% and classical adenocarcinoma (CAC). Clinical and histopathologic findings, recurrence, metastasis, and survival rates were compared. 
Results. Data of the 484 CRC patients were documented. Sixty-nine patients (14.3%) were in the MAC group and 415 (85.7%) patients were in the CAC group. The mean age of patients with MAC and CAC was 63.4 ± 13.5 and 68.5 ± 12.7 years, respectively (p = 0.002). Proximal colon localization was found in 30 (43.5%) MAC patients and 123 (29.6%) CAC patients (p = 0.029). The number of patients with metastatic lymph nodes was higher in the MAC group (58% vs. 41.2%, p = 0.03). Nevertheless, there was no significant difference between the CAC and MAC groups in terms of disease-free survival (63.1% vs. 69.6%, p = 0.37) and disease-related mortality (23.6% vs. 23.2%, p = 0.94) over the follow-up period. Multivariate analysis showed that the presence of perineural invasion, patient’s age, and disease stage were associated with mortality in CRC patients. 
Conclusions. MACs occurred at a younger age than CACs and were more likely localized in the proximal colon as compared to CACs. Despite increased lymph node metastasis in MAC patients, no statistical significance was detected in overall survival or disease-free survival. Multivariate analysis revealed that age, perineural invasion, and disease stage were relevant to mortality in CRC patients.