Microsatellite instability and other molecular abnormalities in non-small cell lung cancer.

Microsatellites are highly polymorphic, short-tandem repeat sequences dispersed throughout the genome. Instability of these repeat sequences at multiple genetic loci may result from mismatch repair errors and occur in hereditary nonpolyposis colorectal carcinoma and certain sporadic cancers. In non-small cell lung cancer, we found that microsatellite instability was infrequent, affecting only 7 (6.5%) of 108 cases. Despite being observed in all histological subtypes and at different tumor stages, microsatellite instability most commonly affected only one of the six loci tested on five chromosomal arms. In addition, microsatellite instability was associated with extensive, concurrent molecular changes including K-ras and p53 mutations as well as frequent loss of heterozygosity at chromosomal regions 5q, 8p, 9p, 11p, and 17p.