Background: Features of index adenomas in the colorectum may be important for the prediction of metachronous adenoma development.
Methods: Complete colonoscopic follow-up for a mean period of 10 years was achieved in 70 of 124 patients after endoscopic polypectomy of an adenoma from the colorectum. On the basis of the clinical outcome, the patients were divided into three groups: Group I, patients who had a colorectum free of adenomas and cancer; Group II, patients who had one or more metachronous adenomatous polyps; and Group III, patients who subsequently had a colorectal carcinoma. The clinical characteristics of the patients were collected, and the neoplastic specimens were re-examined with regard to pathologic parameters and flow cytometrically determined nuclear DNA content.
Results: Aneuploid stemlines were found in 35% of the index adenomas. Significantly more aneuploid adenomas were found in the index adenomas of Group I patients than in the adenomas of Group II patients (r = -0.20; P = 0.05). However, in the index adenomas of Group II patients, aneuploidy was associated with villous architecture (P < 0.05) and inversely related to cellular atypia (P < 0.05). Such relations were not found in the adenomas from Group I. In addition, in the Group II adenomas, aneuploidy was found frequently in the more proximally localized adenomas in the large intestine. Remarkably, all adenocarcinomas of the Group III patients were localized in the right colon. No significant differences were found in ploidy and mean DNA index between index adenomas and metachronous adenomas of the Group II patients. However, the ploidy class of the index adenomas was found not to be related to that of the metachronous adenomas in the individual patients.
Conclusions: These results demonstrate that DNA cytometry in adenomas alone is not helpful in the prediction of the possibility of the development of a metachronous adenoma. However, aneuploidy in a villous adenoma located more proximally in the colon might indicate a higher risk for metachronous neoplasia development. Index and metachronous adenomas are similar in DNA content but show no relation with respect to ploidy class.