Prognostic model of stage II non-small cell lung cancer by a discriminant analysis of the immunohistochemical protein expression

Purpose. We aimed to identify the key proteins that influence the prognosis of non-small cell lung cancer (NSCLC) using protein expression profiles of previously known prognostic markers. Methods. Thirty-one cases of Stage II NSCLC with 5-year follow-up data were selected. Tissue microarrays (TMA) and immunohistochemistry were used to make protein expression profiles of 18 previously reported immunohistochemical prognostic markers and their value in NSCLC was statistically re-evaluated by a discriminant analysis. Results. For the discriminant analysis using marker protein expression profiles, we selected three significant markers, TTF-1, RCAS1 and c-MET, to evaluate each patient's 5-year survival. The requested discriminant function was V = -1.08754 x (RCAS1 score) - 0.83174 x (TTF1 score) + 0.55204 x (cMET score) + 5.46972, and V = 0 served as a cut-off point. The correctness for evaluating a patient's 5-year survival by a discriminant analysis was 87.1%. Conclusions. A discriminant analysis is thus considered to be a useful statistical method for analyzing the protein expression profiles obtained by combined TMA and immunohistochemical techniques using archival NSCLC tissues. However, the sample size and selection of the marker protein depending on the histology greatly influence the results of a NSCLC study.