Deletion at a specific locus in a chromosome in cancer cells is assumed to imply the existence of a tumor-suppressor gene. As a result of multi-step carcinogenesis, there are several hotspots of allelic deletion in lung cancer (1) . The most frequent loci where allelic deletions occur in lung cancer tissues are the short arm of chromosome 3, which contains theFHITgene at 3p14.2, the long arm of chromosome 13, which contains theRB1gene at 13q14, and the short arm of chromosome 17, which contains theTP53gene at 17p13. Deletions at these loci mean loss of the existing tumor-suppressor genes, resulting in carcinogenesis and/or tumorigenesis. Other loci, such as 5q, 9p, and 18q, are also frequently deleted in primary lesion of lung cancer, indicating the possible existence of other tumor-suppressor genes, which may also be responsible for carcinogenesis or early-stage development of lung cancer.
