Flow cytometric analysis of DNA content and proliferation and immunohistochemical staining of Ki-67 in non-small cell lung cancer.

BACKGROUND

The aim of our study was to examine the significance of tumour DNA-content and proliferation in lung cancer.

METHODS

The DNA content and S-phase fraction (SPF) was determined by flow cytometry in 125 resected tumours of patients with non-small cell lung cancer. In 40 cases we compared the SPF with immunohistochemical staining of the Ki-67 protein using MIB-1 antibody.

RESULTS

DNA aneuploidy was detected in 84.8% (106/125). Cell cycle analysis for the determination of proliferation activity was only possible in 69 (55.2%) cases. An SPF of 0-8% as a sign of low proliferation was found in 27 specimens. In advanced tumours at stage III and IV the proportion of tumours with SPF 9-16% was significantly (p<0.05) increased as compared to tumours at stage I and II. There was a significant correlation (p=0.012, ascent: 0.045) between SPF and MIB-1. Patients with aneuploid tumours had a relative risk of 1.4 to die earlier than patients with diploid tumours. Patients with SPF of 9-16% in the tumour tended to decreased survival (5-year survival rate: 29%) in correlation to patients with a percentage of SPF 0-8% (5-year survival rate: 38%, p=0.5). These differences were significant (p=0.048) in patients with adenocarcinomas only. In the multivariate COX-regression model age (p=0.03) and stage (p=0.0001) were significant prognostic factors, ploidy state (p=0.33) was of no prognostic significance.

CONCLUSIONS

Flow cytometry seems to be a useful method for understanding the clinical behaviour of lung cancer. Especially the SPF in adenocarcinomas may be used as a prognostic indicator.