THE ROLE OF FLOW-CYTOMETRY IN CARCINOMA OF THE COLON AND RECTUM

Flow cytometry was performed upon 312 patients with adenocarcinoma of the colon and rectum, satisfactory results being obtained with 275 (10 8 diploid, 130 aneuploid and 37 tetraploid). The proportion of non-dip loid instances increased from 28 percent if one, to 80 percent when si x specimens were assessed per patient. Reproducibility of the techniqu e showed substantial agreement in the assessment of deoxyribonucleic a cid ploidy (Kappa value equals 0.74). Increasing values of cells in th e diving (G2/M) phase of the cell cycle were associated with little ly mphocytic tumor infiltration (p=0.0002) and extensive tumor fibrosis ( p=0.003). Univariate survival analysis revealed that, although diploid tumors tended to have a better prognosis than nondiploid tumors (p=0. 06), no flow cytometric variable was significantly related to survival . Flow cytometry similarly was not of prognostic value in instances wi thout lymph node metastases or without distant metastases. Multivariat e regression analysis of flow cytometric and clinicopathologic variabl es identified Dukes' stage, patient age and tumor differentiation as t he combination of variables most closely related to survival. No flow cytometric variable could significantly improve on the prognostic mode l containing these three variables. It is concluded that conventional histologic variables remain the best predictors of prognosis in carcin oma of the colon and rectum.