Smoky
coal contains
polycyclic aromatic hydrocarbons (PAHs) and has been strongly implicated in etiology of
lung cancer in Xuan Wei, China. While PAHs form bulky adducts in nuclear
DNA, they have a 40-90-fold greater affinity for
mitochondrial DNA (
mtDNA).
mtDNA content may increase to compensate for
mtDNA damage. We conducted a population-based case-control study of
lung cancer in Xuan Wei, China hypothesizing that
mtDNA content is positively associated with
lung cancer risk. Cases (n=122) and controls (n=121) were individually matched on age (+/-2 years), sex, village of residence, and current fuel type. Lifetime smoky
coal use and potential confounders were determined with questionnaires.
mtDNA was extracted from sputum and
mtDNA content was determined with quantitative PCR.
ORs and 95% CIs were calculated with unconditional logistic regression.
mtDNA content >157 copies per cell was associated with
lung cancer risk (OR=1.8; 95% CI=1.0-3.2) compared with those with <or=157 copies. In summary,
mtDNA content was positively associated with
lung cancer risk. Furthermore,
mtDNA content was more strongly associated with
lung cancer risk among older individuals. However, due to the small sample size, additional studies are needed to evaluate this potential association.