This is a prospective study of surgically resected samples and lymph nodes of lung cancer patients. For histopathologically positive lymph nodes from a complete resection, the investigators would like to analyse tumor tissue by allelotyping and comparing these results with those observed in the primary lung tumor to establish a cartography of molecular alteration in resected lung cancer. For non histopathologically positive lymph nodes, the investigators would like to research the presence (or not) of micrometastasis by allele-specific PCR (polymerase chain reaction).