De Novo Submucosal Colorectal Cancer in a 3 mm Sessile Polyp / 대한소화기내시경학회지

The majority of colorectal carcinomas (95~100%) are thought to arise from adenomas. Yet colorectal carcinomas may rarely arise de novo. The popular definition of de novo carcinoma is that the lesion should consist exclusively of a carcinoma histologically and contain no adenomatous elements. Without an adenoma-carcinoma sequence, de novo carcinomas have a much higher rate of submucosal invasion, despite their small size. Their speed of growth is thought to be rapid. Some studies have shown that de novo carcinomas might arise as a macroscopically flat or depressed lesion, rather than a protruded one. However, the typical macroscopic findings of de novo carcinomas have not been established. They might be variable macroscopically and include a protruded type. We report a case of de novo colorectal carcinoma that invaded the submucosal layer involving a minute sessile polyp only 3 mm in diameter, which was removed by endoscopic mucosal resection.

Risk Factors for Lymph Node Metastasis in Patients with Submucosal Invasive Colorectal Carcinoma

PURPOSE: This study was designed to determine the risk factors of lymph node (LN) metastasis in patients with submucosal invasive colorectal cancer (SICC). METHODS: Between January 1998 and January 2009, we reviewed patients who had undergone radical colon resection with LN dissection for SICC. RESULTS: There were 36 males and 40 females (mean age, 61.1 years; range, 35~86 years). In the univariate analysis, the risk of LN metastasis was related to the depth (absolute and relative), lymphovascular invasion, tumor budding, and tumor differentiation (P<0.05). The relative depth by Kudo classification and lymphovascular invasion were significant predictors of LN metastasis both in univariate and multivariate analysis. In SICC with an absolute depth <1,800 microm, no LN metastasis was detected. Regardless of the size of the SICC, tumors that invaded within the sm2 layer and had no lymphovascular invasion had no LN metastasis. CONCLUSION: In the SICC, lymphovascular invasion and depth of submucosal invasion are strong predictors of LN metastasis. If deep invasion exceeds sm2 and positive lymphovascular invasion exists in the resected specimen, additional colectomy with LN dissection appears to be necessary.

The Risk Factors of Lymph Node Metastasis in Submucosal Invasive Colorectal Cancer

PURPOSE: Recent studies have shown a 7~15% lymph node (LN) metastasis rate in submucosal invasive colorectal cancer (SICC). Identification of risk factors for LN metastasis is crucial in the choice of therapeutic modalities for SICC. The present study was performed to assess the possibility of LN metastasis and to determine the risk factors of LN metastasis in SICC. METHODS: A retrospective study of 168 patients with SICC who underwent a curative resection between June 1989 and December 2004 at Asan Medical Center was conducted. The level of submucosal invasion was classified into upper third (sm1), middle third (sm2), and lower third (sm3) according to the submucosal depth of invasion. The following carcinoma-related variables were assessed: tumor size, tumor location, level of submucosal invasion, cell differentiation, lymphovascular invasion, neural invasion, and tumor cell dissociation (TCD). RESULTS: The overall LN metastasis rate was 14.3%. According to the level of submucosal invasion, LN metastasis was seen as follows: sm1, n=4 (4.2%), sm2, n= 10 (21.3%), and sm3, n=10 (38.5%) (P=0.039). According to cell differentiation, LN metastasis was observed as follows: well-differentiated, n=4 (4.9%), moderately differentiated, n=19 (22.9%), and poorly differentiated, n=1 (25.0%) (P=0.028). Nineteen of the 66 cases (28.8%) with TCD had significantly higher risk of LN metastasis as did 5 of the 102 cases (4.9%) without TCD (P=0.045). No statistical difference was observed in the risk of LN metastasis with regard to tumor location, tumor size, neural invasion, or lymphovascular invasion. CONCLUSIONS: Submucosal invasion, cell differentiation, and tumor cell dissociation were significant pathologic predictors of LN metastasis in SICC. As SICC has considerable risk of LN metastasis, local excision should be reserved to highly selective sm1 cancers.