Prognostic significance of hereditary predisposition on the outcome of colorectal cancer as expressed by increased in vitro tetraploidy.

Seventy colorectal cancer patients operated on in the period 1981-1984 were consecutively investigated for in vitro tetraploidy in dermal fibroblasts, as an increased number of tetraploids is considered a marker of genetic predisposition for colorectal cancer. The difference in disease-free survival rates of increased (IVT+) and normal (IVT-) in vitro tetraploidy was not statistically significant (0.1 less than p less than 0.2), but the decrease in the disease-free survival rate of IVT+ was 1.6 times that of IVT-. To exclude the influence of other prognostic factors, a Cox multivariate regression analysis was used, with Dukes C carcinoma and poor differentiation as co-variables for IVT+. In this analysis IVT+ did not show any independent prognostic significance. A genetic predisposition for colorectal cancer, as expressed by the presence of IVT+ in skin fibroblasts, does not seem to influence the survival of patients with colorectal cancer.