Risk of lymph node and distant metastases in patients with early invasive colorectal cancer classified as Haggitt's level 4 invasion: image analysis of submucosal layer invasion.

Purpose: Tumor invasion in patients with early invasive colorectal cancer has been classified into four levels proposed by Haggitt. Level 4 invasion into the submucosa has been defined as a risk factor for lymph node metastasis; however, the false-positive rate remains high. This study was designed to determine risk factors for lymph node and distant metastases in addition to Haggitt's Level 4 invasion.

Methods: Seventy-one of 142 patients with submucosa-invasive colorectal cancer underwent intestinal resection as an initial surgical treatment between 1975 and 2000. The subjects of this study were 65 of these 71 patients, all of whom were diagnosed as having Haggitt's Level 4 invasion. The depth, width, and area of submucosal invasion were measured with an image analyzer.

Results: Lymph node metastasis was noted in 11 (16.9 percent) of the 65 patients. There were no significant differences in the depth or area of submucosal invasion between node-positive and node-negative patients. However, the width of submucosal invasion was significantly greater in node-positive than in node-negative patients (P = 0.001). When 5-mm-wide submucosal invasion was used as an indicator for intestinal resection, 37 patients were found to have indications for bowel resection, and 11 (29.7 percent) of the 37 had lymph node metastases. Distant metastasis was noted in five patients (7.7 percent). The depth, width, and area of submucosal invasion in patients with distant metastasis did not differ significantly from those without distant metastasis.

Conclusion: Although further prospective investigation is required, the positive predictive value increases from 17 to 30 percent when the width of submucosal invasion is added to Haggitt's Level 4 as an indicator for bowel resection.