[Significance of heterozygosity loss in the long arm of chromosome 5 (5q21) in small cell carcinoma of the lung].

BACKGROUND

Loss of heterozygosity (LOH) at 5q21, where the APC/MCC genes reside, is one of the genetic alterations that characterizes lung cancer. The aim of this study was to analyse LOH frequency on chromosome 5q21 in patients with non-small cell lung cancer and its relationship with TNM staging and histological subtypes.

PATIENTS AND METHODS

Tumor and corresponding normal DNA were isolated from 60 patients with non-small cell lung cancer and a subsequent polymerase chain reaction (PCR) with microsatellite markets within the APC/MCC region was performed. The PCR products were resolved by electrophoresis. The comparison between the normal and tumor DNA patterns allowed us to detect the samples harboring LOH.

RESULTS

LOH at 5q21 was detected in 20% of the patients. LOH at 5q21 was found in 16% of stage I patients, 8% in stage II patients and 40% in stage IIIA patients. A trend towards worse survival was detected in stage IIIA patients with LOH at 5q21 (9 months median time survival) in comparison with patients with LOH (21 months), although the difference was not statistically significant (p = 0.11). No significant differences in LOH were observed among histological types. In addition, we found no correlation between LOH and higher frequency of mutations rate affecting K-ras and p53 genes.

CONCLUSIONS

LOH at 5q21 is a frequent genetic alteration in non-small cell lung cancer and correlates with locally advanced disease (stage IIIA). Our results suggest that LOH at the 5q21 region could be a prognostic factor in non-small cell lung cancer.