Men tend to be neoplasia prone and women neoplasia resistant

Patients with a colorectal neoplasm are at risk for metachronous neoplasia. This risk usually is stratified according to the number, size, and histology of the index lesion(s). This study was performed to search for factors contributing not only to a very high risk of metachronous lesions but also to a very low risk.

An extensive neoplasia follow-up database was used to identify patients who were neoplasia prone and neoplasia resistant. Groups were defined as having consecutive colonoscopies that were either all positive or all negative for adenoma(s). Subgroups with two, three, and four consecutive positive or negative examinations were formed, then analyzed for gender, number of index neoplasms, and family history. Patients with familial adenomatous polyposis or with families fulfilling the Amsterdam criteria for hereditary nonpolyposis colorectal cancer were excluded.

The database showed 702 patients who had two follow-up examinations, 103 of which were neoplasia prone and 245 neoplasia resistant. After three consecutive examinations (420 patients), the numbers were 51, and 87, respectively, and after four examinations (231 patients), they were 26 and 34. As the groups became better defined, the proportion of women in the neoplasia-resistant group and the proportion of men in the neoplasia-prone group increased. When gender and number of index lesions were combined, groups were most definitively characterized. Incidence of a positive family history of colorectal cancer was not different between the groups. As the number of follow-up examinations increased, the number of large polyps found decreased.

Groups of patients particularly liable to develop colorectal neoplasia or particularly resistant to it can be identified. Female gender and a single-index lesion favor neoplasia resistance, whereas male gender and multiple-index lesions favor a predisposition for neoplasia.