Risk factors for head and neck cancer in more and less developed countries: Analysis from the INHANCE consortium.

OBJECTIVE: We analyzed the pooled case-control data from the International Head and Neck Cancer Epidemiology (INHANCE) consortium to compare cigarette smoking and alcohol consumption risk factors for head and neck cancer between less developed and more developed countries. SUBJECTS AND METHODS: The location of each study was categorized as either a less developed or more developed country. We compared the risk of overall head and neck cancer and cancer of specific anatomic subsites associated with cigarette smoking and alcohol consumption. Additionally, age and sex distribution between categories was compared. RESULTS: The odds ratios for head and neck cancer sites associated with smoking duration differed between less developed and more developed countries. Smoking greater than 20 years conferred a higher risk for oral cavity and laryngeal cancer in more developed countries, whereas the risk was greater for oropharynx and hypopharynx cancer in less developed countries. Alcohol consumed for more than 20 years conferred a higher risk for oropharynx, hypopharynx, and larynx cancer in less developed countries. The proportion of cases that were young (<45 years) or female differed by country type for some HNC subsites. CONCLUSION: These findings suggest the degree of industrialization and economic development affects the relationship between smoking and alcohol with head and neck cancer.

CYP1A1, CYP2E1, GSTM1, GSTT1, EPHX1 exons 3 and 4, and NAT2 polymorphisms, smoking, consumption of alcohol and fruit and vegetables and risk of head and neck cancer.

PURPOSE: As risk-modifiers of alcohol and tobacco effects, metabolic genes polymorphisms were investigated as susceptibility candidates for squamous cell carcinoma of the head and neck (SCCHN). METHODS: A total of 210 cases and 245 hospital controls, age and gender matched, were genotyped for CYP1A1, CYP2E1, GSTM1, GSTT1, EPHX1 exons 3 and 4, and NAT2 polymorphisms. A measurement of the biological interaction among two risk factors was estimated by the attributable proportion (AP) due to interaction and its 95% confidence interval (CI). RESULTS: SCCHN risk was associated with high-levels of alcohol intake [OR = 3.50 (95%CI: 1.93-6.35) and OR = 6.47 (95%CI: 2.92-14.35) for 19-30 g/day and >30 g/day, respectively], cigarette smoking [OR = 3.47 (95%CI: 1.88-6.41) and OR = 7.65 (95%CI: 4.20-13.90) for 1-25 and >25 pack-years of smoking, respectively] and low-fruit and vegetables consumption (OR = 2.45; 95%CI: 1.53-3.92). No differences were observed for the genotypes or haplotypes distributions among cases and controls, and no biological interaction emerged from gene-gene and gene-environment interaction analyses. An attributable proportion (AP) due to biological interaction of 0.65 (95%CI: 0.40-0.90) was detected for heavy drinkers with a low intake of fruit and vegetables, and an AP of 0.40 (95%CI: 0.10-0.72) resulted forever smokers with low fruit and vegetables consumption. CONCLUSIONS: Even in presence of high alcohol consumption or cigarette smoking, a high intake of fruit and vegetables might prevent the development of around one quarter of SCCHN cases. The lack of interaction between the studied polymorphisms and the environmental exposures suggests that chronic consumption of tobacco and alcohol overwhelm enzyme defences, irrespective of genotype.