Neither the putative risk genotypes ADH1B*2/*1 (OR 0.86, 95% confidence interval (CI): 0.41-1.82) or ADH1C*1/*1 (OR 1.06, CI 0.7-1.62) nor GSTM1 null (OR 0.94, CI 0.62-1.42) or GSTT1 null (OR 1.34, CI 0.74-2.42) were associated with an overall increased risk for laryngeal cancer.
We showed that the risk of developing laryngeal cancer was increased by 2.6-fold [95% CI 1.6--6.1] in patients with the GSTM1 null genotype and by 2.8-fold [95% CI 0.9--8.1] in patients with the homozygous GSTP1 val105 genotype.
In conclusion, this meta-analysis demonstrates that the GSTM1 null gene polymorphism is an increased risk of laryngeal cancer in Asians and Caucasians.
Furthermore, the TP53 mutational hot spots for lung and laryngeal cancers from smokers included codons 157, 245 and 273, whereas for oral tumors included codons 280 and 281.
The combined GSTM3 (AB or BB) and GSTM1-null genotype conferred a 4-fold risk (95% CI, 1.6-10.1) of larynx cancer as compared with the combined GSTM3 AA and GSTM1-positive genotype.
Subgroup analyses by ethnicity showed that the GSTM1 null genotype was associated with increased laryngeal cancer risk in both Caucasians (fixed-effects OR = 1.17, 95 % CI 1.04-1.33, P = 0.012) and Asians (random-effects OR = 1.89, 95 % CI 1.28-2.77, P = 0.001).
We screened exons 5-8 of TP53 for mutations in DNA from tumor biopsies (n = 44) and blood samples (n = 42) from the same LC patients, and blood samples from a healthy, matched control group (n = 40), using polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis and direct sequencing.
TP53 mutations were found in 22 of 58 (37.9%) patients with advanced larynx cancer, including missense mutations in 13 of 58 (22.4%) patients, nonsense mutations in four of 58 (6.9%), and deletions in five of 58 (8.6%).
However, we did not find a significant increase in laryngeal cancer risk for the homozygous Pro/Pro TP53 genotype OR=2.093 (95% CI=1.046-4.192, P=0.0530).
Moreover, a significant interaction between the GSTM1 genotype and levels of tobacco consumption (P < 0.05) was found; the GSTM1 null genotype was associated with an increased risk of larynx cancer among smokers of 20 g/day or less (OR = 2.9, 95% CI = 1.3-6.3) but not among heavier smokers (OR = 1.0; 95% CI = 0.5-2.0).
Neither the putative risk genotypes ADH1B*2/*1 (OR 0.86, 95% confidence interval (CI): 0.41-1.82) or ADH1C*1/*1 (OR 1.06, CI 0.7-1.62) nor GSTM1 null (OR 0.94, CI 0.62-1.42) or GSTT1 null (OR 1.34, CI 0.74-2.42) were associated with an overall increased risk for laryngeal cancer.
These data confirm that the GSTM1 null genotype is an important risk modifier for larynx cancer among Korean smokers and combined GSTM1 and GSTT1 null genotypes could be a useful predictor of genetic susceptibility to larynx cancer.
Firstly, these results confirm the p53 mutational status of laryngeal cancer without any clinical correlation and secondly may suggest an oncogenic potential for the proline/proline genotype of codon 72 for laryngeal cancer as has already been assumed for lung cancer.
The results suggest that the GSTM1 deficiency significantly increases susceptibility to laryngeal cancer whereas GSTT1 null genotype might not be a risk factor.
The combined results based on all studies showed that GSTM1 null genotype was associated with increased laryngeal cancer risk (OR = 1.17, 95% CI = 1.04∼1.31).
This study was conducted to investigate the association between the cyclin D1 gene polymorphism and laryngeal cancer risk, as well as the clinical outcome.