Prognostic significance of ploidy determination in rectal cancer.

Between 1965 and 1981, 154 patients with potentially curable rectal adenocarcinoma underwent surgical treatment at the University of Chicago Medical Center. In 134 cases, enough histological material was available to perform determinations of DNA content by the cytophotometric method (n = 108), or by the flow cytometric technique (n = 109). In 83 cases, DNA content was analyzed in the same specimen with both techniques, and in 77 of these cases the sections obtained from the paraffin blocks were contiguous. When using flow cytometry, 62% of stage B and 74% of stage C lesions were classified as aneuploid on the basis of a DNA index greater than 1. This correlation was statistically significant (p = 0.002). Patients with diploid tumors had an actuarial five-year survival equal to 62% in comparison with a 46-51% five-year survival for patients with aneuploid tumors. This difference was not statistically significant and it was explained by the tendency for aneuploid tumors to be in an advanced histopathological stage.