Mucinous histology as a poor prognostic factor in young patients with Stage II rectal cancer: A population-based...

Mucinous adenocarcinoma (MA) is a distinct histotype of rectal cancer, possibly having prognostic differences with adenocarcinoma (AD). We investigated the prognostic significance of mucinous histology in patients with Stage II rectal cancer.

Eligible patients were retrieved from the Surveillance, Epidemiology, and End Results database from 2004 to 2017, and the survival difference between AD and MA patients in the overall and subgroup populations (divided by age) was compared. Multivariate Cox proportional hazard regression analysis was performed to assess whether the mucinous histotype was an independent prognostic factor.

A total of 10, 910 patients with Stage II rectal cancer were enrolled and divided into a young group (≤55 years, n = 3248) and an old group (>55 years, n = 7662). Patients with MA exhibited a lower cancer-specific survival rate than those with common AD in the overall population and the young group, but not in the old group. The analysis revealed that the mucinous histotype was an independent prognostic factor in the young group, but not in the old group. Moreover, after excluding patients with risk factors (including poorly differentiated or undifferentiated tumor grade, T4 stage, <12 lymph nodes examined, and elevated preoperative carcinoembryonic antigen level), prognosis of the mucinous histotype was poorer in the young group than that in the old group.

The mucinous histotype was an independent prognostic factor in young patients with Stage II rectal cancer. The presence of mucinous histology reflected poor prognosis, especially in the low-risk young population.