Invasive micropapillary carcinoma component is an independent prognosticator of poorer survival in Stage III colorectal cancer patients

Background Invasive micropapillary carcinoma (IMPC) is an aggressive variant of adenocarcinoma found in several organs. Recent studies showed that IMPC in colorectal cancer leads to poorer prognosis than conventional colorectal cancer; however, the influence of IMPC on outcomes remains unclear. The present study aimed to identify the clinicopathological characteristics of colorectal cancers with IMPCs, and to evaluate the prognostic significance of IMPCs per se. Methods We retrospectively analyzed data from 837 patients with colorectal cancer who underwent surgical treatment. We compared the clinicopathological characteristics and survival outcomes of colorectal cancer patients with IMPCs to those without. Results Among 837 patients, 130 (16%) had an IMPC component, including 0 (0%) of 18, 9 (4.2%) of 215, 34 (13%) of 254, 59 (24%) of 249 and 28 (27%) of 101 patients with TNM Stages 0, I, II, III and IV, respectively. The 3-year disease-free survival (DFS) rates were significantly worse for Stage III patients with IMPC than for those without (55.3% vs. 78.7% respectively, P < 0.001), but not in patients with other stages. Multivariate analyses of patients with Stage III colorectal cancer found IMPC to be associated with significantly worse DFS (P = 0.026), as were high CEA levels, tumor budding and TNM staging. IMPC was only significantly associated with tumor invasion (P = 0.045) and venous invasion (P = 0.045) in Stage III tumors. Conclusions Identifying IMPC components in Stage III colorectal cancer is crucial, as their presence is significantly associated with poorer survival.