DNA adducts linked to oral cancer in smokers

By Sarah Guy, medwireNews Reporter

Having a high susceptibility to certain types of DNA damage caused by tobacco smoking could significantly increase the risk for oral cancer, show results of a Taiwanese study.

Levels of BaP 7,8-diol 9,10-epoxide (BPDE) - a metabolite of Benzo[a]pyrene, an important carcinogen found in cigarette smoke - correlated positively with smoking status in a cohort of individuals with oral cancer, report the researchers.

The findings also indicate a significantly increased risk for oral cancer among individuals with high DNA adduct levels compared with their peers with low levels.

"Based on our finding, we suggest that detected BPDE-like DNA adducts could be used as a biomarker for oral cancer risk," write Huei Lee (Taipei Medical University) and colleagues in the Archives of Oral Biology.

The team analyzed BPDE-DNA adduct levels in oral tissue samples from 158 oral cancer patients and 64 individuals without cancer (controls), using immunohistochemistry and enzyme-linked immunosorbent assay (ELISA).

The results of these assays significantly and positively correlated , so that immunohistochemistry-negative patients did not have detectable DNA adduct levels using ELISA and vice versa.

DNA adduct levels also positively correlated with smoking status among the cancer patients, note the researchers, with significantly higher adduct levels among smokers than nonsmokers, at 93.18 versus 0.04 adducts per 10⁸ nucleotides.

Lee and co-workers also observed that cancer patients had significantly higher DNA adduct levels than controls, at a range of 0-358.00 versus 0-39.50 adducts per 10⁸ nucleotides.

Indeed, DNA adduct level was an independent risk biomarker for oral cancer in multivariate analysis, which indicated a 9.94-fold increased risk for the disease among individuals with high levels, defined as more than two standard deviations above the mean adduct level in the low group - which equates to 34.03 adducts per 10⁸ nucleotides.

"These results strongly suggest that a high susceptibility to DNA damage derived from exposure to cigarette carcinogens is associated with the high risk of oral cancer in Taiwanese oral cancer patients," conclude Lee et al.

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