Prospective study of Ki-67 labeling index in the mucosa adjacent to cancer as a marker for colorectal cancer metastasis.

Multivariate regression analysis has shown that Ki-67 labeling index in the mucosa adjacent to cancer was the most significant marker for colorectal cancer metastasis among several metastasis-related parameters according to our previous retrospective data base (7). We have performed a prospective study to ascertain whether Ki-67 labeling index in the mucosa adjacent to cancer is a useful preoperative diagnostic marker for colorectal cancer metastasis. In 182 registered cases colonoscopically biopsied, we performed surgical resection of the cancer in 37 adenocarcinoma cases, which were registered in the study. In 31 out of the 37 cases except for 6 cases with an insufficient amount of non-neoplastic mucosa, preoperative diagnosis for metastasis was performed using the Ki-67 cutoff line. The cutoff line was set at 15% according to our previous retrospective database. The preoperative diagnosis for metastasis was compared to the pathological findings of the resected specimen. The incidences of correct diagnosis for metastasis was 81% (25/31). There were 3 false positive cases and 3 false negative cases in Dukes' A-B and Dukes' C, respectively. The mean Ki-67 labeling index in the mucosa adjacent to cancer of Dukes' A-B and Dukes' C-D cases, except for the 6 misdiagnosed cases, was 7.4+/-5.0% and 29.9+9.8%, being significant at p<0.0001 by unpaired Mann-Whitney U test. These results suggest that Ki-67 labeling index in the mucosa adjacent to cancer might be a good marker for metastasis in colorectal cancer.