Importance of lymph node status in lung cancer: In patients with non-small cell lung cancer (NSCLC), tumor stage is the strongest determinant of prognosis. Stratification of patients into stages facilitates individual treatment decisions based on the survival statistics of a population. Within these staged populations however, subsets of patients with apparent early disease will still suffer cancer recurrence. This is due to the inability of current staging methods to detect small numbers of disseminated tumor cells (micrometastases) in these patients. Reverse transcription-PCR (RT-PCR) for cancer related messenger RNA's has been shown to detect the presence of micrometastases in histologically negative lymph node specimens, and these findings correlate with poor outcome. Unfortunately, routine clinical application of this technique has been limited by "false positive" results in control tissues and a low specificity for predicting disease recurrence. We have recently shown that quantitative RT-PCR (QRT-PCR) can discriminate between true and false positives, and that this results in an improved ability to predict recurrence. In this proposal we intend to analyze lymph nodes from patients undergoing surgical resection for NSCLC using quantitative RT-PCR. These patients will then be followed for five years to determine tumor recurrence. The goal is to use QRT-PCR to try and identify which patients are at highest risk for disease recurrence and who may therefore benefit from more aggressive therapies.