Prognostic significance of p53 protein expression and DNA ploidy in surgically treated non-small cell lung carcinomas.

A series of 112 patients operated for non-small cell lung cancer was analyzed retrospectively. Nuclear suspensions were prepared from formalin-fixed, paraffin-embedded biopsies, and DNA content was measured simultaneously with p53 expression using flow cytometry. The expression of p53 protein was determined by the monoclonal antibody PAb 1801, which recognizes both wild-type (normal) and mutated forms of p53. By the level of p53 expression, four patient groups were statistically defined. Patients in the two groups with no detectable and extremely high p53 expression had a significantly better prognosis than patients in the two groups with moderately increased p53 expression. By logistic regression, p53 expression was found to be the single best predictor of 5 year survival. Patient age and tumor stage were less important prognostic factors. No difference in 5 year survival was observed between diploid and aneuploid tumors. We conclude that p53 is a useful prognostic predictor in low stage non-small cell lung carcinoma using the monoclonal antibody PAb 1801. The applicability of this antibody to archival material in flow cytometric analysis should allow a broad range of tumor types to be analyzed with respect to the prognostic significance of p53 overexpression.