Asbestos burden in lungs of mesothelioma patients with pleural plaques, lung fibrosis and/or ferruginous bodies at histology: a postmortem SEM-EDS study.

The causal attribution of asbestos-related diseases to past asbestos exposures is of crucial importance in clinical and legal contexts. Often this evaluation is made based on the history of exposure, but this method presents important limitations. To assess past asbestos exposure, pleural plaques (PP), lung fibrosis and histological evidence of ferruginous bodies (FB) can be used in combination with anamnestic data. However, such markers have never been associated with a threshold value of inhaled asbestos. With this study we attempted to shed light on the dose-response relationship of PP, lung fibrosis and FBs, investigating if their prevalence in exposed individuals who died from malignant mesothelioma (MM) is related to the concentration of asbestos in lungs assessed using scanning electron microscopy equipped with energy dispersive spectroscopy. Moreover, we estimated the values of asbestos concentration in lungs associated with PP, lung fibrosis and FB. Lung fibrosis showed a significant positive relationship with asbestos lung content, whereas PP and FB did not. We identified, for the first time, critical lung concentrations of asbestos related to the presence of PP, lung fibrosis and FB at histology (respectively, 19 800, 26 400 and 27 400 fibers per gram of dry weight), that were all well-below the background levels of asbestos identified in our laboratory. Such data suggest that PP, lung fibrosis and FB at histology should be used with caution in the causal attribution of MM to past asbestos exposures, while evaluation of amphibole lung content using analytical electron microscopy should be preferred.

A postmortem case control study of asbestos burden in lungs of malignant mesothelioma cases.

BACKGROUND: Asbestos lung content is regarded as the most reliable tool for causal attribution of malignant mesothelioma (MM) to previous asbestos exposures. However, there is a lack of studies on asbestos burden in lungs of MM patients in comparison with healthy individuals. This study aims to provide such a comparison, investigating, as well, differences in asbestos lung burden with sex and time trends. METHODS: Asbestos lung content has been assessed on formalin-fixed lung fragments using scanning electron microscopy coupled with energy dispersion spectroscopy (SEM-EDS) on individuals deceased from MM (cases) and healthy subjects without any lung disease who died from violent causes (controls) between 2005 and 2023. RESULTS: Asbestos and asbestos bodies (ABs) were found, respectively, in 73.7% and 43.2% of cases and in 28 and 22% of controls; in MM cases the most represented asbestos types were crocidolite and amosite, whereas in controls it was tremolite-actinolite asbestos. The concentration of both asbestos fibers and ABs was statistically significantly higher in MM cases compared to controls. The mean asbestos fibers width was also significantly higher in cases than controls. Males and females with MM showed similar asbestos and ABs concentrations, but females had higher concentrations of chrysotile, and significantly lower fibers width compared to males. Time trends show that MM lung asbestos concentrations decreased starting in 2011. DISCUSSION: The results suggest a correlation between asbestos burden in lungs and MM risk. The different concentration of chrysotile, as well as the different width of asbestos fibers in MM males and females might reflect a sex difference in response of the lung microenvironment to inhaled asbestos. Finally, this study provides the first pathological evidence of the effect of the ban of asbestos use, demonstrating a significant decrease of asbestos lung content after 2011.

Recurrence-free survival after total thyroidectomy and lobectomy in patients with papillary thyroid microcarcinoma.

PURPOSE: The incidence of papillary thyroid microcarcinoma is increasing. We evaluated the recurrence-free survival following total thyroidectomy and lobectomy to identify the optimal surgical choice. METHODS: A meta-analysis was performed using the National Library of Medicine and the National Institutes of Health PubMed database to identify eligible studies. Summary 5- and 10-year RFS estimates after TT versus LT were calculated using random effects models. RESULTS: The literature search yielded 1117 studies (1990-2019). Nine studies met the inclusion criteria comprising 10,186 total thyroidectomy and 11,408 lobectomy patients. The 5-year recurrence-free survival was 98% [95% confidence interval (CI) 97-99%] after total thyroidectomy and 97% (95% CI 96-99%) after lobectomy, based on eight studies (9421 total thyroidectomy and 11,283 lobectomy patients); the 10-year recurrence-free survival was 95% (95% CI 92-98%) after total thyroidectomy and 92% (95% CI 86-96%) after lobectomy, based on eight studies (total thyroidectomy = 10,100, lobectomy = 11,389 patients). CONCLUSION: The present meta-analysis demonstrates excellent, long-term recurrence-free survival following both total thyroidectomy and lobectomy surgery in patients with papillary thyroid microcarcinoma. The analysis also suggests that patients undergoing total thyroidectomy trended toward a slightly better long-term 10-year recurrence-free survival in comparison to patients undergoing lobectomy, a finding of potential, clinical significance in the management decision-making process.

Associations between human papillomavirus and history of cancer among U.S. adults in the National Health and Nutrition Examination Survey (2003-2010).

BACKGROUND: Human papillomavirus (HPV) is an infectious agent that has been associated with human cancer. We have updated the U.S. population sero-prevalence using a large National Health and Nutrition Examination Survey (NHANES) sample of adults from 2003 to 2010, and have analysed the associations between HPV seropositivity and self-reported history of cancer. METHODS: Four cross-sectional cycles (2003-2004, 2005-2006, 2007-2008, and 2009-2010) were used, for a total of 12 759 participants who had both cancer history and HPV serum information. RESULTS: The sero-prevalences of HPV types 6, 11, 16, and 18 were 15.0%, 4.8%, 11.5%, and 4.1%, respectively. Females had significantly higher HPV prevalence than males (P<0.05) for all subtypes. Positive associations between HPV 16/18 seropositivity and lifetime history of any cancer (adjusted odds ratio-ORadj=1.68; 95% CI: 1.35, 2.01), history of any of eight selected cancers (ORadj=2.63; 95% CI: 1.78, 3.90), lung cancer (ORadj=5.14; 95% CI: 1.29, 20.44), and cervical cancer (ORadj=2.55; 95% CI: 1.63, 3.98) were observed. CONCLUSIONS: The finding of significant associations between HPV 16/18 seropositivity and lifetime history of cancer adds epidemiological evidence to the carcinogenicity potential of HPV 16 and 18 in other tissues. With increasing coverage of the HPV vaccine in the U.S., future NHANES data and sample collection may allow further detailed evaluation of the population impact of the HPV vaccination on cancer prevention.

Cleft lip and palate in family members of cancer survivors.

The presence of cleft lip with or without cleft palate (CL/P) in family members of cancer patients was investigated. An epidemiological questionnaire including family history of cancer and congenital oral cleft malformations was administered to 168 cancer survivors and a population-based sample of 170 healthy subjects. In the control group, 1.2% reported a family member with CL/P; among cancer survivors the figure was 4.2% (odds ratio: 3.7; 95% confidence interval: 0.75­17.8; p = .07). Among cancer survivors with a family member with CL/P, there was an apparent excess of testicular cancer and melanoma in comparison with the cancer survivors with no family history of CL/P. These preliminary results suggest a common etiologic background for cancer and CL/P.

Meta- and pooled analyses of the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and colorectal cancer: a HuGE-GSEC review.

Worldwide, over 1 million cases of colorectal cancer (CRC) were reported in 2002, with a 50% mortality rate, making CRC the second most common cancer in adults. Certain racial/ethnic populations continue to experience a disproportionate burden of CRC. A common polymorphism in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene has been associated with a lower risk of CRC. The authors performed both a meta-analysis (29 studies; 11,936 cases, 18,714 controls) and a pooled analysis (14 studies; 5,068 cases, 7,876 controls) of the C677T MTHFR polymorphism and CRC, with stratification by racial/ethnic population and behavioral risk factors. There were few studies on different racial/ethnic populations. The overall meta-analysis odds ratio for CRC for persons with the TT genotype was 0.83 (95% confidence interval (CI): 0.77, 0.90). An inverse association was observed in whites (odds ratio = 0.83, 95% CI: 0.74, 0.94) and Asians (odds ratio = 0.80, 95% CI: 0.67, 0.96) but not in Latinos or blacks. Similar results were observed for Asians, Latinos, and blacks in the pooled analysis. The inverse association between the MTHFR 677TT polymorphism and CRC was not significantly modified by smoking status or body mass index; however, it was present in regular alcohol users only. The MTHFR 677TT polymorphism seems to be associated with a reduced risk of CRC, but this may not hold true for all populations.

Review and pooled analysis of studies on MTHFR C677T polymorphism and esophageal cancer.

Esophageal cancer has been associated with tobacco and alcohol consumption, gastric reflux, exposure to nitrosamines from food or other environmental sources, and diets lacking folate. Susceptibility to esophageal cancer may be modified by functional polymorphisms in genes along the folate metabolic pathway, such as methylenetetrahydrofolate reductase (MTHFR). The C677T polymorphism is the most common functional variant, leading to a reduction in enzyme activity. We report a pooled analysis of 5 studies on the association of MTHFR C677T polymorphism and esophageal cancer, including 725 cases and 1531 controls. A significant association between the MTHFR 677 TT genotype and esophageal cancer was observed (OR=2.63, 95% CI: 1.75-3.94), although there was significant heterogeneity between studies. A sensitivity analysis excluded one study; the association between TT genotype and esophageal cancer was still present, although of reduced magnitude (OR=1.57, 95% CI: 0.96-2.56). A significant interaction between smoking and TT genotype on esophageal cancer risk was observed, while no interaction was observed between alcohol consumption and genotype.

Effect of vitamin levels on biomarkers of exposure and oxidative damage-the EXPAH study.

DNA adducts are markers of carcinogen exposure and of their biological effect; they have been shown to be related to mutagenesis, and therefore they could be a predictive biomarker of human cancer. The objective of this study was to assess if there is a relationship between vitamins A, C, and E, which are known to play a significant role as free radical scavengers and antioxidant agents, and biomarkers of genotoxicity and oxidative stress. Three hundred and fifty-six subjects from Czech Republic, Slovak Republic and Bulgaria, who completed a questionnaire on dietary information and had a measurement of plasma A, C, E vitamins, DNA adduct levels (benzo[a]pyrene (B[a]P) and bulky (DNA-Tot) DNA adducts) and oxidative damage (cyclic pyrimidopurinone N-1,N2 malondialdehyde-2 deoxyguanosine (M1dG) and 8-oxo-7,8-dihydro-2_deoxyguanosine (8-oxodG)) were analyzed. A significant inverse correlation was observed between plasma vitamin levels and both benzo[a]pyrene (B[a]P) and bulky DNA adducts. Vitamin A was also significantly inversely correlated with M1dG, a marker of oxidative damage. The associations were stronger in non-smokers than in smokers. Dietary intake of certain antioxidants such as vitamins is associated with reduced levels of markers of DNA damage (B[a]P and DNA-Tot) and oxidation (M1dG and 8-oxodG) measured in peripheral white blood cells. This could contribute to the protective role of such a dietary pattern on cancer risk. The protective effect of dietary vitamins is less evident in smokers.

Cancer screening and cancer mortality in Nevis, West Indies.

OBJECTIVE: Cancer screening is one approach that can reduce morbidity and mortality through early detection of pre-cancers; however anxiety, fear, and lack of information are important barriers to universal cancer screening in the Caribbean. Nevis is a small island located in the Eastern Caribbean. We report available data on screening prevalence and cancer mortality for four common cancers: cervical, breast, colon and prostate. METHODS: Demographic information, screening utilization (when available) and cancer mortality statistics were obtained from the Charlestown Health Clinic and the annual reports from the Ministry of Health. Moreover physicians and key stakeholders were interviewed to assess current guidelines for cancer screening as well as to indicate areas of need. RESULTS: Cervical cancer screening is under-utilized in Nevis. Between 2001 and 2007, the overall prevalence of Pap testing fluctuated minutely (mean: 6.87%, range: 6.06-7.41%). Systematic screening for breast, colon, and prostate cancer is not routinely performed, thus utilization rates are not available. Cancer mortality varied slightly between 2002 and 2006; prostate cancer had the highest overall crude mortality rate (30.6 deaths/100,000 persons). Physician interviews revealed that adherence to US and European cancer screening guidelines are inappropriate for their population of patients. Breast and prostate cancers are frequently diagnosed in these geographic areas before the age when cancer screening is currently recommended. CONCLUSION: Cancer is perceived as an important health problem by physicians, key stakeholders and citizens, however cancer screening is under-utilized in Nevis. Future research should focus on generating screening guidelines that are relevant for this population, as well as methods to promote screening.

Prevalence of cancer-associated viral infections in healthy afro-Caribbean populations: a review of the literature.

Cancer is one of the five leading causes of death in the Caribbean. Viral infections have been associated with cancer development and propagation, but the prevalence of such infections in the Caribbean is unknown. This review of the published literature shows that in 161,196 subjects from 14 Caribbean Islands, the adjusted prevalence of HHV8 infection is 4.5%, HTLV-1: 1.0%, HPV: 57.5%, HCV: 0.4%, HBV: 9.4%, and EBV: 92.2%. With the exception of HCV, the prevalence was significantly higher in the Caribbean than in the United States. These findings may significantly contribute to the high incidence of cancer observed in the Caribbean.

Association of A313 G polymorphism (GSTP1*B) in the glutathione-S-transferase P1 gene with sporadic Parkinson's disease.

Genetic predisposition, environmental toxins and aging contribute to Parkinson's disease (PD) multifactorial etiology. Weak environmental neurotoxic factors may accumulate over time increasing the disease risk in genetically predisposed subjects. Polymorphic genes encoding drug-metabolizing-enzymes (DMEs) are considered to account for PD susceptibility by determining individual toxic response variability. In this work, the allelic distributions and genotype associations of three major brain-expressed DMEs were characterized, in sporadic PD cases and controls. No significant association was found between CYP2D6 genotype and PD, but subjects with extensive metabolizer (EM) CYP2D6 phenotype, and the variant GSTP1*B genotype were at significantly higher PD risk than the corresponding poor or intermediary metabolizers (CYP2D6 poor metabolizer phenotype+intermediary metabolizers). A significant association was observed between the GSTP1*B allele and zygosity with PD (GSTP1*A/*B- 51.58%/34.37%, odds ratio (OR) = 2.29; 95% confidence interval (95% CI) = 1.25-4.18; *B/*B- 6.32%/1.05%, OR = 10.67; 95% CI = 1.19-94.79). This association was particularly strong in the elder patients group (> or =69 year) who showed double PD risk for GSTP1*B heterozygous, whilst GSTP1*B/*B homozygous were exclusively found amongst patients. An interaction between GSTM1 and GSTP1 was observed in this late onset PD group. The present results suggest that native GSTP1 encoding the fully active transferase variant should play a relevant role in dopaminergic neuroprotection.

Predictors of moderate and severe injuries in Italian major leagues soccer teams: results from a cohort study.

AIM: The possible consequences of injury in soccer players could be a relevant public health issue, due the large diffusion of this sport around the world. We have evaluated the predictive value of both personal and professional characteristics on the occurrence of injuries and their severity in a prospective cohort study. METHODS: A cohort of 1 041 professional soccer players from the two Italian major Leagues was assembled during the season 2003-2004: 743 out of 785 subjects available the day of the interview (94.6%) answered an epidemiological questionnaire. A validation study was performed to assess if participating subjects were representative of the whole cohort. The risk of injuries and their severity according to several variables were assessed. RESULTS: A total of 157 subjects suffered 177 injuries during the season 2002-2003. Differences exist between injured and non-injured players according to both the number of matches played during the season and the League. A trend in risk of injury with anthropometric measures was observed, although not significant. The type of tissue and the type of injury were significantly associated with the duration of the stop. CONCLUSION: Anthropometric measures and career history (such as type of League and number of played matches) could require further attention, since they seem to be predictive of injury occurrence in soccer players.

A CYP1A1 restriction fragment length polymorphism is associated with breast cancer in African-American women.

We examined the role of CYP1A1 polymorphisms as potential molecular markers of breast cancer susceptibility in Caucasian and African-American women. The case-control study involved 51 women with breast cancer and 269 female controls. In African-Americans, the frequency of the homozygous MspI polymorphism was 3.5% in controls and 19% in breast cancer cases. The odds ratio of breast cancer with the MspI homozygous variant was 9.7 (95% confidence interval: 2.0-47.9). This association was not observed in Caucasian women. The exon 7 and AA polymorphisms were not associated with breast cancer in either group. The mechanism for the observed association between the MspI polymorphism and breast cancer is unclear. It is possible that the CYP1A1 MspI RFLP is linked with other polymorphisms in the African-American population, either in the CYP1A1 gene, which is involved in estrogen metabolism, or other genes related to risk of breast cancer.

A specific African-American CYP1A1 polymorphism is associated with adenocarcinoma of the lung.

A case-control study on lung cancer in African-Americans has been conducted to assess whether a novel African-American-specific polymorphism in the CYP1A1 gene increases the susceptibility to tobacco-related lung cancer. The prevalence of the AA RFLP was 17.1% in the DNA extracted from archived tissue blocks from 76 incident cases of lung cancer, and was 16.3% in peripheral blood lymphocyte DNA of 123 healthy African-American volunteers recruited from a community in the eastern United States. The analysis by histological type showed an association between adenocarcinoma (AC) of the lung and the AA RFLP (odds ratio, 2.6; 95% confidence interval, 1.1-6.3). One homozygous variant subject was present among the AC cases. The risk of AC in subjects who both smoke and carry the AA RFLP was more than double, in comparison to subjects who only smoke (relative interaction magnitude under the additive model, 24%). The mean value of pack-year in AC with the polymorphism was 5.0 +/- 2.5 and in AC without the polymorphism was 37.2 +/- 6.5 (P < 0.05). Our data suggest that a selective association exists between the AA polymorphism and adenocarcinoma of the lung and that a lower dose of tobacco is sufficient to exert carcinogenic effects on the adenomatous tissue of subjects carrying the AA polymorphism.

Prevalence of Salmonella enterica and Listeria monocytogenes contamination in foods of animal origin in Italy.

The present survey collected and analyzed the results of routine testing for Salmonella enterica and Listeria monocytogenes on foods of animal origin submitted for official controls in Italy during 2001 to 2002. Salmonella was detected in 2.2% of 71,643 food samples examined, and the isolation rates ranged from 9.9% for raw poultry meat to less than 0.1% for dairy products. Isolation rates were also high in raw pork (4.9%) and processed meats (5.3%), which often involved pork. Low rates were observed in seafood (0.5%) and in ready-to-eat foods, such as grocery products (0.7%) and ice creams (0.1%). Serotyping showed that approximately 50% of the isolates belonged to the serotypes most commonly isolated from humans in Italy, thus confirming that most cases of human salmonellosis have a foodborne origin. Levels of L. monocytogenes were higher than what is accepted by the current regulation in 2.4% of 42,300 food samples. The positivity rates ranged from 10.3% in raw pork to none in eggs and egg products. Contamination rates were higher in other meat products (between 2 and 5%) and fish (6.5%) than in cheeses (1.1%) and other dairy products (0.6%). Routine control activities on the microbial contamination of foods can generate data with statistical and epidemiological value. Such data can be used as a basis for estimating the exposure of consumers to foodborne pathogens, following the trends of contamination over time, and evaluating the effects of control measures on the contamination of food.

Quality evaluation of solid organ transplant in Italy for the period 2000 to 2002 data from the national transplant center.

BACKGROUND: As part of the increased need for transparency and disclosure of information in health care, the Italian Minister of Health has commissioned the Superior Institute of Health to study health outcomes for several procedures, among which is solid organ transplants. We herein report the results of a quality evaluation of solid organ transplants and on the relationship between hospital volume of activity and outcomes, using the data routinely collected by the National Transplant Center during the period 2000 to 2002. METHODS: We collected and analyzed all the information on solid organ transplants between 2000 and 2002, along with clinical information before and after transplant. Multivariate survival analysis was performed to adjust the follow-up data for the complexity of the cases. Correlation graphs are presented that assess the association between the number of transplants and the adjusted 1-year survival of both the organ and the patient. RESULTS: One-year survival was 92.4% for kidney, 77.8% for liver, and 83.9% for heart. Patient survival was 97.0%, 84.1%, and 83.9%, respectively. A negative correlation was observed between the number of transplants performed by each center and 1-year survival of the organ. CONCLUSIONS: Our study indicated that survival after organ transplants in Italy is good and that hospital quality, indirectly measured through survival, overlaps that observed in other Western countries.

Human exposure to dioxins through diet in Italy.

We have measured the content of polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans (together defined as "dioxins") in 269 samples of food of animal origin collected through the regional veterinary services, covering the national territory. Quantification of the dioxins was accomplished by isotope dilution method, and toxic equivalents (TEQ) were calculated. The average daily food intake was obtained from two main sources: national data collected by the National Institute of Nutrition, and data from an ongoing cohort study on diet and cancer including 40,000 Italian subjects. The mean value of dioxins measured in food of animal origin was 0.144 +/- 0.266 pg-TEQ/g (range: 0.003-1.655 pg-TEQ/g). Fish was the item with the highest content. The estimated intake of dioxins with main food items of animal origin is presented. The major contribution to dioxins intake with food comes from cow milk and fish consumption. These results are in agreement with what observed in studies conducted in other countries, such as Germany, Finland, Japan, Spain, and are below the limits set by the European legislation.

Recognition of oxidized DNA bases by sera of patients with inflammatory diseases.

Chronic inflammatory conditions result from or contribute to many diseases. Prominent among them is systemic lupus erythematosus (SLE). Sera of SLE patients contain an array of various auto-antibodies (Ab), including antinuclear Ab of unknown etiologies. The most puzzling is formation of Ab directed against autologous DNA. Our hypothesis was that increased oxidant production causes oxidation of DNA bases, which provide antigenic determinants that elicit antioxidized DNA Ab. To test this hypothesis, we used oxidized DNA nucleoside (5-hydroxymethyl-2'-deoxyuridine [HMdU]) conjugated to bovine serum albumin (HMdU-BSA) as the antigen. The results of the enzyme-linked immunosorbent assay showed that these Abs are sensitively detectable in SLE sera and sera of various other inflammatory autoimmune diseases. The titers of anti-HMdU Ab were significantly higher (p < .01) than those present in the control sera. Anti-HMdU Ab were predominantly of the IgM isotype, with low levels of IgG and no IgA. Anti-HMdU Ab bound to the HMdU-BSA-coated wells in a concentration- and time-dependent manner. That binding was inhibited by HMdU-BSA and to a lesser extent by thymidine-BSA, a normal nucleoside conjugate. The specific binding appears to be inversely related to the age of the patients, but no significant differences were observed between the sexes of the same age.

Lack of interaction between asbestos exposure and glutathione S-transferase M1 and T1 genotypes in lung carcinogenesis.

An interaction between occupational carcinogens and genetic susceptibility factors in determining individual lung cancer risk is biologically plausible, but the interpretation of available studies are limited by the small number of exposed subjects. We selected from the international database on Genetic Susceptibility and Environmental Carcinogens the studies of lung cancer that included information on metabolic polymorphisms and occupational exposures. Adequate data were available for asbestos exposure and GSTM1 (five studies) and GSTT1 (three studies) polymorphisms. For GSTM1, the pooled analysis included 651 cases and 983 controls. The odds ratio (OR) of lung cancer was 2.0 [95% confidence interval (CI) 1.4-2.7] for asbestos exposure and 1.1 (95% CI 0.9-1.4) for GSTM1-null genotype. The OR of interaction between asbestos and GSTM1 polymorphism was 1.1 (95% CI 0.6-2.1) based on 54 cases and 53 controls who were asbestos exposed and GSTM1 null. The case-only approach, which was based on 869 lung cancer cases and had an 80% power to detect an OR of interaction of 1.56, also provided lack of evidence of interaction. The analysis of possible interaction between GSTT1 polymorphism and asbestos exposure in relation to lung cancer was based on 619 cases. The prevalence OR of GSTT1-null genotype and asbestos exposure was 1.1 (95% CI 0.6-2.0). Our results do not support the hypothesis that the risk of lung cancer after asbestos exposure differs according to GSTM1 genotype. The low statistical power of the pooled analysis for GSTT1 genotypes hampered any firm conclusion. No adequate data were available to assess other interactions between occupational exposures and metabolic polymorphisms.

Effects of indole-3-carbinol on the metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone in smokers.

Indole-3-carbinol (I3C) is a component of the human diet, occurring as a conjugate in certain cruciferous vegetables. I3C protects against carcinogenesis in a variety of animal models by modifying carcinogen metabolism. In mice, I3C decreases lung tumor formation by the tobacco-specific nitrosamine 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) by enhancing its hepatic clearance (M. A. Morse et al., Cancer Res., 50: 2613-2617, 1990). In this study, our goal was to determine whether I3C would have similar effects on NNK metabolism in smokers as it did in mice. Thirteen women took 400 mg of I3C on 5 consecutive days and maintained constant smoking habits during this period. Their urine was analyzed before and after the I3C treatment period for two metabolites of NNK: 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronide (NNAL-Gluc). I3C treatment resulted in decreased levels of urinary NNAL, NNAL-Gluc, and NNAL plus NNAL-Gluc, and increased NNAL-Gluc:NNAL ratio in 10 of the 13 women. The mean decreases in NNAL (-0.27 +/- 0.09 pmol/mg creatinine, -23.4%) and NNAL plus NNAL-Gluc (-0.43 +/- 0.16 pmol/mg creatinine, -10.9%) were statistically significant as was the increase in NNAL-Gluc:NNAL ratio (1.1 +/- 0.5, 39.9%). These changes in urinary metabolites of NNK were consistent with those seen in mice treated with I3C and NNK; they suggest that I3C increased hepatic metabolism of NNK in our smokers. This is the first study to examine the effects of I3C on metabolism of an exogenous carcinogen in humans.