The influence of tumour cell DNA content on survival in colorectal cancer: a detailed analysis.

We have investigated the influence of tumour cell DNA content (ploidy) on survival of 416 patients undergoing excisional surgery for colorectal cancer. Two hundred and eleven (51%) tumours had an abnormal DNA content (aneuploid or tetraploid). There was no correlation between ploidy status, sex, age and pathological stage, histological grade, tumour site, local tumour extension or assessment of curability. Patients with tumours with an abnormal DNA content had a poorer survival 68/211 (32%) than patients with near normal (diploid) DNA content 88/205 (43%) (test statistic 5.0, P = 0.02). The patient subgroups in which DNA content exerted an influence on survival were: stage B tumours (P = 0.0058), moderately differentiated tumours (P = 0.004), rectal tumours (P = 0.02), and mobile tumours (P = 0.02). Multivariant analysis showed that pathological stage, local tumour extension and DNA ploidy were all independent prognostic indicators whereas histological grade, tumour site and assessment of 'curability' were not. The influence of pathological stage, however, was much greater than that of local tumor extension or DNA ploidy. Tumour cell DNA content together with pathological stage and local tumour extension may be used in a prognostic index and may be important in planning adjuvant therapy.