Background: A minority of patients (30-40%) with advanced non-small cell lung cancer (NSCLC) have objective responses to chemotherapy. Therefore, defining molecular features that determine resistance or response to chemotherapy would have important implications in this disease. Several studies have suggested that patients whose tumors have neuroendocrine features may be more responsive to chemotherapy. In addition, increased expression of p53 may play a role in chemotherapy resistance in patients with NSCLC.
Methods: The objective of this study was to analyze retrospectively, the correlation between marker expression and response to chemotherapy and survival using immunohistochemistry for neuroendocrine markers and p53. Ninety patients with unresectable stage III or IV NSCLC, treated with platinum based combination chemotherapy were evaluated. The pathological specimens were obtained prior to chemotherapy.
Results: There was no statistically significant correlation between any individual marker and response to chemotherapy. However, patients with tumors with increased expression of p53 were more likely to have progressive disease following chemotherapy (P=0.02). Similarly, patients with tumors lacking neuroendocrine expression and with increased expression of p53 were more likely to have progressive disease when compared to patients with tumors with normal p53 expression and neuroendocrine differentiation (P=0.03). Normal expression of p53 along with the presence of neuroendocrine differentiation was a favorable factor for both survival (P=0.05) and time to disease progression (P=0.04) in the multivariate analysis.
Conclusion: The presence of neuroendocrine markers alone was not predictive of response to chemotherapy and did not impact on the survival of this group of patients with advanced stage NSCLC. The normal expression of p53 together with neuroendocrine differentiation seems to impact favorably on overall survival time and time to disease progression without significant improvement in response to chemotherapy.