Clinical trial NCT01158456: Metabolism of NNK Among African Americans
Official title: Mechanisms of Ethnic/Racial Differences in Lung Cancer Due to Cigarette Smoking: Project 5: Metabolism of NNK Among African Americans
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Lung Cancer
Keywords: smoking
lung cancer
ethnic racial differences
tobacco specific nitrosamines
metabolism of carcinogens
Lead sponsor: Masonic Cancer Center, University of Minnesota
Sponsor class: OTHER
Collaborators: name: National Cancer Institute (NCI)
First posted: 2010-07-08
Enrollment: 161
Sex: ALL
Minimum age (years): 21
Maximum age (years): 65
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Observational model: COHORT
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Subjects will be classified as African American if they report themselves, biological parents and both sets of biological grandparents as African American or African descent. Similar criteria will be applied to European Americans (e.g., self, both parents and four grandparents of European American or European descent). Subjects will be evenly divided by gender.

Brief summary: Metabolism and DNA adduct formation are critical in cancer induction by NNK. The investigators goal is to understand whether the observed ethnic/racial differences in lung cancer incidence are due to variations in NNK metabolism. The investigators overall hypothesis is that cancer susceptibility relates to carcinogen dose and to the balance between carcinogen metabolic activation and detoxification. The investigators propose to test this hypothesis via investigation of potential differences in NNK metabolic activation and detoxification in African American and European American smokers.

Detailed description: Lung cancer is the most common cause of cancer death in the United States, with the annual number of cases estimated at 162,460 deaths per year. It is more prevalent in African Americans as compared to European Americans. Cigarette smoking causes up to 90% of lung cancer, being the major risk factor in both African Americans and European Americans.

Tobacco-specific nitrosamines (TSNA) are among the most significant carcinogens in tobacco products. Multiple international studies clearly document the occurrence of substantial amounts of these carcinogens in both unburned tobacco and tobacco smoke. One of the most prevalent of these compounds, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), is present in both unburned tobacco and cigarette smoke, and is a remarkably effective lung carcinogen in laboratory animals, inducing lung tumors in rodents independent of the route of administration. 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a metabolite of NNK, is also a pulmonary carcinogen. NNK has been classified by the International Agency for Research on Cancer as a Group 1 carcinogen (carcinogenic to humans). Consistent with this, 2 recent studies by our group have demonstrated that levels of NNAL in serum or urine are related to lung cancer in smokers.

Our primary aim is to conduct a comprehensive analysis of urinary biomarkers of NNK metabolic activation and detoxification in African American and European American smokers. We hypothesize that, after adjustment for smoking level, the relative contribution of the biomarkers of NNK metabolic activation to the total amount of NNK metabolites will be higher in African Americans as compared to European Americans. Our secondary aim is to measure in exfoliated oral mucosa cells of African American and European American smokers DNA adducts formed as a result of NNK metabolic activation. The results of these measurements will offer a direct measure of NNK-induced DNA damage in smokers, and will be critical to an understanding of the balance between the urinary excretion of NNK metabolites and the extent of NNK DNA binding. We hypothesize that African Americans will have in the DNA of their oral mucosa cells higher levels of NNK-derived DNA adducts as compared to European Americans. Finally, we will investigate the relationship between levels of NNK-derived DNA adducts measured in oral mucosa cells and the rates of repair of these adducts in cultured lymphocytes from our subjects. These measurements will allow us to evaluate more fully the role of variations in NNK metabolism in the observed differences in lung cancer risk between European American and African American smokers. We expect that that African Americans will have lower capacity to repair NNK-induced DNA damage as compared to European Americans, and this will correlate with higher levels of NNK-derived buccal DNA adducts.

Eligibility criteria: Inclusion Criteria:

1. Male or female subjects with a smoking history of at least 10 cigarettes daily for at least 1 year;
2. Subjects report themselves, biological parents and both sets of biological grandparents as

   * African American or African descent or
   * European American or European descent
3. Subjects are in apparently good physical health (no unstable medical condition)
4. Subjects are in stable, good mental health (e.g. not currently, within the past 6 months, experiencing unstable or untreated psychiatric diagnosis, including substance abuse, as determined by the PRIME-MD);
5. Subjects have provided written informed consent to participate in the study.

Exclusion Criteria:

1. Unstable medical conditions including cancer, coronary heart disease and arrhythmia
2. Cannot or unwilling to identify ethnic/racial ancestry
3. Women who are currently pregnant or breast feeding
4. Currently using any other tobacco or nicotine-containing product
5. Currently taking any medications that affect relevant metabolic enzymes.

Primary outcomes:
measure: Conduct a comprehensive analysis of urinary biomarkers of NNK metabolic activation and detoxification in African American and European American smokers.
timeFrame: 10 days
Secondary outcomes:
measure: Measure in exfoliated oral mucosa cells of African American and European American smokers DNA adducts formed as a result of NNK metabolic activation.
timeFrame: 10 days
measure: Assess the repair of NNK-induced DNA damage.
timeFrame: 10 days
Other outcomes:
Locations:
city: Minneapolis
country: United States
facility: Tobacco Research Programs University of Minnesota
state: Minnesota
Study officials:
affiliation: University of Minnesota
name: Dorothy K Hatsukami, Ph.D.
role: PRINCIPAL_INVESTIGATOR
References: