Background: Alterations of the p53 gene are one of the most common genetic changes in various types of cancer, including lung cancer. Abnormalities in the ras genes, including point mutations and overexpression, are another common feature in the molecular biology of lung cancer and are associated with a poorer prognosis. The authors' purpose was to determine expression of the mutated p53 gene in nonsmall cell lung cancer (NSCLC) specimens that were studied for expression of ras p21 and to document whether altered p53 expression was also an important factor for survival.
Methods: Ninety-six patients with NSCLC underwent surgical resection between 1977 and 1985, 63 of whom received postoperative combination chemotherapy. None received radiation therapy. Tumor specimens were analyzed for altered p53 expression by immunohistochemistry. Univariate and multivariate analyses were performed to assess the association between p53 expression and survival.
Results: Fifty-six (58%) of 96 tumor specimens showed altered p53 expression, and 91 patients were analyzed for survival. Altered p53 expression did not correlate with clinicopathologic characteristics except for postsurgical pathologic tumor (pT) classification. The patients with altered p53 expression survived for a significantly shorter period after surgery than those without p53 expression, including all patients who underwent resection and potentially curative resection (P = 0.02 and P = 0.048, respectively, generalized Wilcoxon test). Multivariate analysis showed independent prognostic significance for altered p53 expression (hazard ratio [HR] = 1.72, P = 0.04) and surgical cure (HR = 4.69, P < 0.001). The combined analysis of mutated p53 and ras p21 expression in the same tumor specimens revealed that patients with p53- and ras p21-negative tumors survived the longest among those with different p53 and ras p21 features (P = 0.005, generalized Wilcoxon test).
Conclusion: Altered p53 expression is a significant and independent negative prognostic factor for patients with surgically resected NSCLC: Combined immunohistochemical analysis of mutated p53 and ras p21 expression can divide patients with NSCLC into more accurate prognostic groups. If the current findings can be confirmed in larger prospective studies, combined immunohistochemical analysis of mutated p53 and ras p21 expression can be a useful clinical tool for stratifying patients with NSCLC into accurate prognostic groups and for identifying the population with a different risk of recurrence.