Vali Constantinescu

Exon 5 Polymorphisms in the O6-Alkylguanine DNA Alkyltransferase Gene and Lung Cancer Risk in Non–Smokers Exposed to Second-Hand Smoke

Purpose: The objective of the study was to examine the association of three exon 5 variants in the O6-alkylguanine DNA alkyltransferase (AGT) gene involved in the repair of the mutagenic DNA lesion O6-alkylguanine formed by nitrosamines, with lung cancer risk in never-smokers. Experimental Design: Exon 5 of the AGT gene was sequenced in genomic DNA from 136 cases and 133 hospital- or population-based controls for whom questionnaire information on second-hand smoke and diet was available to determine the frequencies of the Gly160Arg, Ile143Val, and Lys178Arg variant alleles. Results: No codon 160Arg variant alleles were found in the study population. The codon 143Val and 178Arg variant alleles, present at allele frequencies of 0.07, showed 100% linkage. The odds ratio (OR) of lung cancer for these variant carriers was 2.05 [95% confidence interval (CI) 1.03–4.07]. The risk varied between the different lung cancer pathologies with an increased risk for adenocarcinoma (OR 2.67, 95% CI 1.21–5.87) or small cell carcinoma (OR 4.83, 95% CI 0.91–25.7) but not for squamous cell carcinoma (OR 1.07, 95% CI 0.27–4.18). Compared with individuals carrying the mutant alleles unexposed to second-hand smoke, the OR for exposed variant carriers was 1.95 (95% CI 0.53–1.15); a similar interaction, although not significative, was observed for low consumption of cruciferous vegetables and for green vegetables and tomatoes. Conclusions: These results point toward a role of AGT polymorphisms in lung cancer susceptibility among never-smokers, in particular among subjects exposed to environmental carcinogens.

Occupational exposure to vinyl chloride, acrylonitrile and styrene and lung cancer risk (Europe)

Several industry-based cohort studies have addressed the risk of lung cancer following exposure to vinyl chloride, acrylonitrile and styrene, with inconsistent results and usually without smoking adjustment. These exposures are addressed here in a large case–control study with full adjustment for smoking.Almost 6000 subjects were included in a case–control study conducted in seven European countries. For each job they held, local experts assessed the exposure to a number of occupational agents, including vinyl chloride, acrylonitrile and styrene, on the basis of detailed occupational questionnaires. Information on tobacco consumption and other risk factors was also collected.The odds ratio (OR) for ever exposure to vinyl chloride was 1.05 (95% confidence interval, CI: 0.68–1.62) and a modest, non-significant increase in the risk of lung cancer was found in the highest exposed subgroup. The OR for ever exposure to acrylonitrile was 2.20 (95% CI: 1.11–4.36) with a positive dose–response relationship between estimated cumulative exposure and lung cancer risk. No association between exposure to styrene and lung cancer risk was found. In conclusion, we cannot exclude a weak association between occupational exposure to vinyl chloride and lung cancer risk. Exposure to acrylonitrile was associated in our study with risk of lung cancer. Exposure to styrene does not seem to increase lung cancer risk.

Exposure to environmental tobacco smoke and risk of adenocarcinoma of the lung

We conducted a case‐control study of adenocarcinoma of the lung and exposure to environmental tobacco smoke (ETS) in 7 countries. We interviewed 70 cases of adenocarcinoma of the lung and 178 population or hospital controls. All subjects had smoked fewer than 400 cigarettes in their lifetimes. Ever exposure to ETS from the parents during childhood was associated with a decreased risk [odds ratio (OR) 0.6, 95% confidence interval (CI) 0.3–1.2], and there was a suggestion of a decreasing trend in risk with increasing duration of exposure. Ever exposure to ETS from the spouse was not associated with an increased risk (OR 1.0, 95% CI 0.5–1.8), while the OR of ever exposure to ETS at the workplace was 1.5 (95% CI 0.8–3.0). For both exposure sources, an increased risk was observed among the highly exposed, and the OR among those with the highest duration of exposure to ETS from the spouse or at the workplace was 1.8 (95% CI 0.5–6.2). A similar risk was estimated for current exposure to ETS from either source. Our results confirm previous reports of a weak effect of adult ETS exposure on risk of adenocarcinoma of the lung. Bias and confounding cannot be excluded as explanations for the apparent decrease in risk from childhood exposure. Int. J. Cancer 83:635–639, 1999.

O6-Alkylguanine-DNA-alkyltransferase activity in peripheral leukocytes, smoking and risk of lung cancer

The level of activity of O6-alkylguanine-DNA-alkyltransferase (AGT), a DNA repair enzyme, in blood lymphocytes may be a marker of susceptibility to lung cancer. We measured the AGT activity level, expressed as pmoles of repaired bases/mg protein, in leukocytes of 153 lung cancer cases (of whom 80 were never smokers) and 106 controls (76 never smokers) enrolled in eight centres from seven countries. Subjects were interviewed with respect to active smoking and exposure to environmental tobacco smoke (ETS). Among never smokers, the odds ratios (ORs) of lung cancer were 1.3 (95% confidence interval 0.5-3.9), 1.5 (0.6-4.1) and 1.4 (0.5-3.8) in quartiles of decreasing AGT activity level, as compared to the upper quartile (P value of test for linear trend 0.6). Corresponding ORs among smokers were 3.4 (0.9-13), 2.0 (0.5-8.3) and 0.4 (0.1-1.6) (P value of test for linear trend 0.4). No interaction was suggested between AGT activity level and either cumulative smoking or exposure to ETS. Reduced AGT activity was not clearly associated with increased lung cancer risk in either smokers or non-smokers. However, the small size of our study argues for a prudent interpretation of our results.

Lack of association between serum antibodies of Chlamydia pneumoniae infection and the risk of lung cancer.

Lack of association between serum antibodies of Chlamydia pneumoniae infection and the risk of lung cancer.