Aberrant p53 staining does not predict cisplatin resistance in locally advanced non-small cell lung cancer

Cisplatin based chemotherapies have increased the survival in nonsmall cell lung cancer. A mechanism for identifying tumors resistant to cisplatin would be useful in avoiding unnecessary toxicity of platinum regimens. Mutation of p53 has been shown to induce chemotherapy resistance in vitro. We hypothesized that tumors staining for p53 would be resistant to cisplatin. In Cancer and Leukemia Group B protocol 8935, patients with stage IIIA (N2 node positive) nonsmall cell lung cancer received chemotherapy followed by surgery, then post-operative chemotherapy and/or radiation. All patients underwent pre-treatment staging mediastinoscopy. Twenty-five out of forty-nine pre-treatment mediastinal lymph node specimens stained positively for p53. Positive staining did not correlate with response to chemotherapy or survival. It did predict a slightly higher complete or partial resection rate compared to negative staining (76 vs. 45%) (p = 0.042). A trend toward longer median survivals was seen in patients with positive p53 staining. This study does not support the ability of p53 staining to predict chemotherapy resistance.