Clinicopathological characteristics of poorly differentiated adenocarcinoma of the colon and rectum.

Background/Aims: The clinicopathological significance of poorly differentiated adenocarcinoma (Por) of the colorectum remains controversial. The purpose of this study was to investigate the clinicopathological characteristics of Por by comparison with well (Well) and moderately differentiated adenocarcinoma (Mod) of the colorectum and by subclassification of Por into three types according to the amount of fibrous stroma in tumor tissue. Methodology: Eleven patients with Por, 64 with Well and 254 with Mod were clinicopathologically compared. Results: Por was located predominantly in the right side of the colon. The maximal size of the tumors in Por (72.3±25.0mm) was significantly larger than in Well (42.2±26.8mm) and Mod (52.2±22.8mm) (p=0.0009, 0.0047). The frequency of lymph node metastasis in Por was significantly higher than in Well (p=0.0009). The five-year survival rate for patients with Por was 45.5%, for Well was 71.4% and for Mod was 59.5% (NS). The medullary type of Por had a good prognosis. Conclusions: Por proliferated and metastasized more rapidly than Well. The subclassification of Por according to the amount of fibrous stroma in tumor tissue could play an important role in the clinicopathological study of colorectal carcinoma.