Methods for assessing cancer susceptibility to carcinogens in tobacco products
The present invention demonstrates the differential sensitivity of PBLs from lung cancer patients and healthy controls to NNK-induced genetic damage. The data provide convincing evidence that the preferred CBMN assay is a robust test for detection of this sensitivity and yields results that are a good predictor of, for example, lung cancer risk. The simplicity, rapidity, and sensitivity of the CBMN test make it a valuable tool for screening and, for example, prioritizing potential cases for early detection of the disease.
1. A method for assessing cancer susceptibility to carcinogens in tobacco smoke in a human subject that has not been diagnosed with lung cancer, comprising the steps of:
(a) obtaining a sample, wherein the sample comprises nucleated cells obtained from the subject;
(b) assaying the sample by determining the frequency of chromosomal damage endpoints in the nucleated cells;
(c) assessing cancer susceptibility to carcinogens in tobacco smoke as a function of the chromosomal damage endpoint frequency.
2. The method of claim 1 , wherein the human subject is a known cigarette smoker.
3. The method of claim 1 , wherein the subject has a familial history of cancer.
4. The method of claim 1 , wherein the sample is a blood sample.
5. The method of claim 1 , wherein the chromosomal damage endpoints are selected from the group consisting of micronuclei (MN), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs).
6. The method of claim 1 , wherein determining the frequency of chromosomal damage endpoints comprises determining said frequency in nucleated cells that have not been treated with nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK).
7. The method of claim 6 , wherein the chromosomal damage endpoints are further defined as spontaneous micronuclei (MN), nucleoplasmic bridges (NPBs) or nuclear buds (NBUDs).
8. The method of claim 1 , wherein determining the frequency of chromosomal damage endpoints comprises determining said frequency in nucleated cells that have been treated with nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK).
9. The method of claim 8 , wherein the chromosomal damage endpoints are further defined as NNK-treated MN, NPBs or NBUDs.
10. The method of claim 5 , wherein MNs are quantified by means of the assay.
11. The method of claim 5 , wherein NPBs are quantified by means of the assay.
12. The method of claim 5 , wherein NBUDs are quantified by means of the assay.
13. The method of claim 5 , wherein at least two of MNs, NPBs or NBUDs are quantified by means of the assay.
14. The method of claim 13 , wherein all three of MNs, NPBs or NBUDs are quantified by means of the assay.
15. The method of claim 1 , wherein determining the frequency of chromosomal damage endpoints comprises subjecting the nucleated cells to a cytokinesis-block micronucleus (CBMN) assay.
16. The method of claim 15 , wherein the CBMN assay is automated.
17. The method of claim 1 , wherein a selected number of nucleated cells are assayed, and the frequency of chromosomal damage endpoints is determined as a per/cell average of the selected number of cells.
18. The method of claim 17 , wherein at least about 500 nucleated cells are assayed.
19. The method of claim 18 , wherein at least about 1000 nucleated cells are assayed.
20. The method of claim 1 , wherein an increased susceptibility to cancer in the subject is indicated by a higher number of chromosomal damage endpoints as compared to a control number.
21. The method of claim 20 , wherein the control number is obtained by conducting the assessment method of steps (a), (b) and (c) on a control population representative of the population as a whole.
22. The method of claim 20 , wherein a predicted fold increase in risk is determined.
23. The method of claim 20 , wherein a subject who demonstrates an increased susceptibility is placed in a follow-up or screening program.
24. The method of claim 1 , wherein the nucleated cells are reticulocytes, buccal cells, bladder wash cells, fibroblasts or lymphocytes.
25. The method of claim 24 , wherein the nucleated cells are lymphocytes.
26. The method of claim 25 , wherein the lymphocytes are peripheral blood lymphocytes.
27. The method of claim 1 , wherein the cancer susceptibility is defined as susceptibility to lung cancer, squamous cell carcinoma of the head and neck or bladder cancer.
28. The method of claim 27 , wherein the cancer susceptibility is susceptibility to adenocarcinoma of the lung.