Clinicopathological Characteristics of Small Advanced Colorectal Carcinoma

抄録

The majority of colorectal carcinomas develop from preexisting polypoid adenomas, although some colorectal carcinomas can arise from flat or depressed neoplasias. In general, flat or depressed lesions are smaller than polypoid adenomas. The aim of this study is to clarify clinicopathologic characteristics of small advanced colorectal carcinoma. Patients with small advanced carcinoma were retrospectively recruited from 1,078 consecutive patients who had undergone surgical resection. Small advanced carcinomas were defined as those where the tumor size was 2cm or less in diameter and where the tumor had invaded the muscularis propria (pT2) or beyond (pT3-4). These carcinomas were classified as polypoid growth (PG) or non-polypoid growth (NPG) carcinomas. Among the 1,078 carcinoma cases there were 58 (5.4%) cases of small advanced carcinoma of which 13 (22%) were PG carcinomas and 45 (78%) were NPG carcinomas. The prevalence of pT3 invasion was significantly higher in NPG (17 of 45; 38%) than in PG carcinomas (1 of 13; 8%, P=0.04). The incidence of vascular invasion was also significantly higher in NPG (40 of 45; 89%) than in PG carcinomas (8 of 13, 62%; P=0.02). Approximately 80% of small advanced colorectal carcinomas were NPG carcinomas. A review of the clinicopathologic characteristics of small NPG carcinomas demonstrated that these tumors have a high incidence of vascular invasion with infiltration into deep tissue layers.