Association of genetic dependences between lung cancer and chronic obstructive pulmonary disease

Recent studies have shown an increased risk of lung cancer in patients with bronchial obstructive changes, including patients with COPD. It seems that there are common factors of pathogenesis of both diseases associated with oxidative stress. In the present paper the genes linked to the repair of oxidative damage of DNA, associated with cancer, of iron metabolism and coding proteolytic enzymes were assessed.

The study was conducted in two groups of patients: 53 patients with non-small cell lung cancer and chronic obstructive pulmonary disease, and 54 patients only with chronic obstructive pulmonary disease. The polymorphisms of the single nucleotide were determined in the case of the majority of genes using the PCR-RFLP method. The statistical analysis of quantitative variables was executed using the Mann-Withney U-test and the test of medians; the analysis of genetic variables was executed using the chi² test.

Regarding the polymorphisms of genes involved in iron metabolism, statistically significant differences between the two groups have been demonstrated only in the case of haptoglobin gene HP1/2. A higher incidence of form 1/1 was found in patients with COPD and a higher incidence of form 1/2 in patients with lung cancer and COPD. Analysis of gene polymorphisms of proteolytic enzymes and inhibitors of the enzyme gene showed statistically significant differences between the two groups only for the MMP3 gene 6A/5A. In the case of the MMP12 gene polymorphism (A-82G) a tendency toward differences in the occurrence of specific alleles was identified.

These results indicate that patients with coincidence of COPD and lung cancer have disorders of the genes involved in iron metabolism, and they have different genetic polymorphisms of proteolytic enzymes comparing to COPD patients.