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 canc er. In 40 cases we compared the SPF with immunohistochemical staining of th e Ki-67 protein using MIB-1 antibody. Results. DNA aneuploidy was detected in 84.8% (106/125). Cell cycle analysi s 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 tumou rs with SPF 9-16% was significantly (p <0.05) increased as compared to tumo urs 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 relat ive 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 survi val 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=0.04 8) in patients with adenocarcinomas only. In the multivariate COX-regressio n model age (p=0.03) and stage (p=0.0001) were significant prognostic facto rs, ploidy state (P=0.33) was of no prognostic significance. Conclusions. Flow cytometry seems to be a useful method for understanding t he clinical behaviour of lung cancer. Especially the SPIT in adenocarcinoma s may be used as a prognostic indicator.