Simultaneous detection of apoptosis and proliferation in colorectal carcinoma by multiparameter flow cytometry allows separation of high and low-turnover tumors with distinct clinical outcome

Abstract

BACKGROUND. Dukes C colorectal carcinoma is treated with adjuvant chemotherapy. Adjuvant treatment is not standard for patients with Dukes B tumors, even though about 20% of patients within this tumor stage die of recurrent disease. The authors investigated whether a novel method of simultaneous detection of apoptosis and proliferation would improve the assessment of prognosis in colorectal carcinoma patients, with the ultimate goal of accurately identifying patients eligible for adjuvant therapy. METHODS. A multiparameter flow cytometric assay with heat pretreatment was performed on 278 paraffin-embedded colorectal adenocarcinomas. After immunochemical isolation of tumor cells, apoptosis and proliferation were assessed simultaneously by immunostaining for the M30 antibody and by quantitative DNA analysis, respectively. Patients were followed for more than 10 years. RESULTS. The mean values of apoptosis (apoptotic fraction [AF], i.e., the percentage of M30-positive cells) and proliferation (S-phase fraction [SPF]) were 11.1% and 13.1%, respectively. The AF and SPF values were correlated positively (P = 0.01) and both increased with advancing tumor stage (P = 0.02). Combining AF and SPF, patients with tumors with a high turnover (i.e., both AF and SPF values were greater than the mean) had an overall survival rate of 13%, whereas patients with low-turnover tumors (i.e., both AF and SPF values were less than the mean) had an overall survival rate of 89% (P < 0.001 by log rank test). Moreover, within Dukes B and C stages, patients with high-turnover tumors had a poorer survival than patients with low-turnover tumors (P < 0.001 for both stages). CONCLUSIONS. The simultaneous detection of apoptosis and proliferation in archival material allows separation of high and low-turnover colorectal adenocarcinomas and improves the assessment of prognosis. This technique could be used to stratify patients for adjuvant chemotherapy. © 2003 American Cancer Society.