Purpose: Previous reports have suggested that mucinous colorectal adenocarcinomas are more advanced at diagnosis and have a poorer prognosis than nonmucinous colorectal adenocarcinomas. The purpose of this study was to clarify whether the mucin-producing histologic type of carcinoma is associated with a worse prognosis than nonmucinous, differentiated colorectal adenocarcinoma for patients who undergo curative surgery.
Methods: Using a database of 2,678 surgical patients with colorectal cancers operated on at Aichi Cancer Center between 1965 and 1994, we investigated 97 cases of mucinous adenocarcinoma and 2,197 cases of nonmucinous adenocarcinoma. We also evaluated the outcomes of patients who underwent surgery with curative intent. To determine whether the mucinous adenocarcinoma itself was an independent prognostic factor in the curative resected patients, a multivariate analysis was performed.
Results: The mucinous adenocarcinoma patients were found to be younger (P = 0.0003), have more lymph node involvement (48.5 vs 40.3 percent; P = 0.0564), more peritoneal dissemination (19.6 vs 5.6 percent; P < 0.0001), greater frequency of advanced stage disease (P = 0.0006), a lower rate of curative resection (76.3 vs 84.4 percent; P = 0.0450), and lower overall 5-year survival rates (41 vs 62.4 percent; P = 0.0002) than nonmucinous adenocarcinoma patients. In the subjects who underwent curative resection, the 5-year survival rate for those with mucinous adenocarcinoma was significantly worse than for those with nonmucinous adenocarcinoma (54 vs 73.3 percent; P = 0.0020). Multivariate analysis using the Cox proportional hazards model showed that the clinically significant predictive factors were stage at diagnosis, mucinous histology, tumor location, gender and age. The mucinous histologic type itself was an independent factor for poor prognosis for patients who underwent curative surgery.
Conclusions: In patients with colorectal carcinomas who underwent surgery with curative intent and who had colorectal carcinomas of the mucinous histologic type, there was significant correlation with prognosis as measured by overall survival rate after adjustment had been made for major confounders.