Prognostic Role of Acellular Mucin Pools in Patients with Rectal Cancer after Pathological Complete Response to Preoperative Chemoradiation: Systematic Review and Meta-Analysis

The prognostic implication of acellular mucin pools (AMP) in rectal cancer is controversial. There is no Level-I evidence regarding their prognostic impact. This systematic review was performed to determine the impact of AMP on survival in patients with rectal cancer, who demonstrate pathological complete response (PCR) to preoperative chemoradiation (CRT). A systematic literature review was performed by searching MEDLINE and EMBASE database. For overall survival, the overall random effect model favored mucin negative tumors (HR=2, 95% CI=0.8-4.8) with heterogeneity (I-squared=0, p=0.6). However, the pooled analysis was not significant due to small sample. For disease-free survival, four studies showed HR >1; however, the pooled random effect model indicated little difference in risk (HR=1.06, 95% CI=0.4-2.4) with heterogeneity (I-squared=49.5%, p=0.07). No definite prognostic role of AMP in rectal cancer patients with PCR was found. These results, however, should be interpreted with caution.