Prognostic value of the apoptotic index analysed jointly with selected cell cycle regulators and proliferation markers in non-small cell lung cancer

In a previous small series of surgically treated non-small cell lung cancer patients (NSCLC), we found that higher apoptotic index (AI) negatively influenced survival (Dworakowska D, Jassem E, Jassem J, Karmolinski A, Dworakowski R, Wirth T, et al. Clinical significance of apoptotic index in non-small cell lung cancer: correlation with p53, mdm2, pRb and p21WAF1/CIP1 protein expression. J Cancer Res Clin Oncol 2005; 131:617–623.). In this study we attempted to verify our previous finding in larger group of 170 NSCLC cases, additionally correlating AI to selected cell cycle regulators as well as a proliferation marker. Apoptosis was assessed with the use of the TUNEL technique, whereas the expression of p53, pRb, mdm2, p21^WAF1/CIP1, cyclin D1 and PCNA were assessed immunohistochemically. The mean and the median AI was 12 and 8, respectively. The expression of p53, pRb, mdm2, p21^WAF1/CIP1 proteins and cyclin D1 was found in 47%, 71%, 37%, 65% and 40% of cases, respectively. The mean and the median PCNA labeling index (PCNA LI) was 34 and 35, respectively. AI was not correlated with any patient characteristic or other tumor markers. In uni- and multivariate analysis AI, analysed separately or jointly with cell cycle regulators and PCNA LI, did not influence disease-free or over-all survival. However, patients with “very high AI/very high PCNA LI” had a particularly poor prognosis (P = 0.001). Patients with “very low AI/negative pRb” phenotype survived for a shorter time in comparison to others (P = 0.04). In addition, patients with the highest PCNA LI had a worse outcome in comparison to patients with the lowest PCNA LI (P = 0.04), especially those with concomitant p53 protein expression (P = 0.026) or lacking pRb protein expression (P = 0.04). This study demonstrates that joint analysis of several factors involved in apoptosis, proliferation and cell cycle regulation, but not AI alone, might provide additional prognostic information in NSCLC patients.