DNA aneuploidy in colorectal adenomas. Role in the adenoma-carcinoma sequence.

Introduction: Aneuploidy has been observed in 6-27% of lesions known to be precursors of colorectal cancer, such as adenomas or ulcerative colitis. It has been suggested that aneuploidy may predispose to malignancy in these cases. However, its role in the adenoma-carcinoma sequence has not been definitely established. The objective of this study was to assess the incidence of aneuploidy in colon adenomas, as well as to study its possible role in the adenoma-carcinoma sequence.

Material And Methods: The study was performed on a series of 57 large bowel adenomas measuring 10 mm or more, collected from 54 consecutive patients. All specimens were obtained either by endoscopic or by surgical resection. There were 49 adenomas with low-grade dysplasia, two with high-grade dysplasia, two intramucous carcinomas, and four microinvasive carcinomas. A flow cytometric DNA analysis was performed in fresh specimens following Vindelov's method.

Results: Aneuploid DNA was detected in five out of 49 low-grade dysplasia adenomas (10%), in all four high-grade dysplasia adenomas or intramucous carcinomas (100%), and in three out of four microinvasive carcinomas (75%). The association between aneuploidy and high-grade dysplasia adenomas, intramucous, or microinvasive carcinoma was statistically significant (p < 0.001). No association was found between aneuploidy and any of the following features: age, gender, clinical symptoms of patients, and size or location of adenomas.

Conclusions: The incidence of aneuploidy in this series was 10% in low-grade dysplasia adenomas, and 87% in high-grade dysplasia adenomas or carcinomas, and this difference was statistically significant. These findings suggest that aneuploidy may play a role in the adenoma-carcinoma sequence.