Variation in the promoter region of the myeloperoxidase gene is not directly related to lung cancer risk among male smokers in Finland

In order to examine whether a polymorphism in the promoter region of the myeloperoxidase (MPO) gene is associated with lung cancer among male smokers, we conducted a case–control study nested within a Finnish clinical trial cohort. Although we found no evidence of an overall association between lung cancer risk and MPO genotype, the variant MPO genotype was associated with an increased risk of lung cancer among a subset of older men. These findings contrast with those from previous studies that report decreased lung cancer risk among MPO variant individuals.