Metaphase cytogenetics and DNA flow cytometry with analysis of S-phase fraction in prostate cancer: influence on prognosis.

OBJECTIVES

To compare the prognostic significance of chromosome aberrations, DNA ploidy, and S-phase fraction (SPF) in prostate adenocarcinomas and to compare the sensitivity of metaphase cytogenetics with flow cytometry (FCM) in detecting abnormal tumor clones.

METHODS

Prostate adenocarcinomas from 57 men were previously successfully analyzed with metaphase cytogenetics. Archival material from these tumors were further analyzed with FCM for DNA content and SPF.

RESULTS

The patients were followed for 4.5 to 7.7 years. DNA ploidy was analyzed in 51, and SPF in 45 of the 57 tumors. Clonal chromosomal aberrations, DNA aneuploidy, and high SPF were all significantly associated with poor survival. Of these three variables, SPF was the best predictor of survival, but compared with tumor stage and grade in multivariate analysis, SPF was not an independent prognostic factor. Patients with locally advanced tumors or metastatic disease with SPF less than 8% had a median survival of 5.9 years, compared with only 1.3 years for those with SPF more than 8%. Twenty-eight abnormal clones were detected with FCM and 20 with cytogenetic analysis, but only for two of these clones could the results from the two different methods be regarded as concordant.

CONCLUSIONS

SPF was superior to karyotype and ploidy in predicting death in prostate cancer, but it remains to be shown whether SPF analysis adds prognostic information to tumor stage and grade. The cytogenetic analyses correlated poorly with results of FCM, indicating low sensitivity of both methods.