This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cloos, J. Articles by Braakhuis, B. J. M. Search for Related Content PubMed PubMed Citation Articles by Cloos, J. Articles by Braakhuis, B. J. M.

Mutagen Sensitivity as a Biomarker for Second Primary Tumors after Head and Neck Squamous Cell Carcinoma¹

Department of Otolaryngology/Head and Neck Surgery [J. C., C. R. L., M. L. T. v. d. S., G. B. S., B. J. M. B.] and Department of Epidemiology and Biostatistics [D. J. K.], University Hospital Vrije Universiteit, 1007 MB, Amsterdam, the Netherlands

	Abstract

Top Abstract Introduction Materials and Methods Results Discussion References

 
The occurrence of second primary tumors after curative treatment of early stage head and neck squamous cell carcinoma negatively influences the overall survival. Our aim was to prospectively evaluate whether mutagen sensitivity (mean number of chromatid breaks per cell in cultured lymphocytes exposed to bleomycin) could be used as a biomarker to predict which patients will develop second malignancies in the respiratory or upper digestive tract. Patients treated for head and neck squamous cell carcinoma (n = 218) were followed for approximately 6 years. Nineteen patients developed a second primary tumor, and each of these patients was matched on age, gender, cumulative smoking, tumor site, and tumor stage to two patients who did not develop any second malignancy. No difference between the groups was found with respect to mutagen sensitivity. Smoking at the time of the index tumor had a significant influence on the occurrence of second primary tumors (log-rank, P = 0.019). There was a significantly (P = 0.005) higher mean breaks-per-cell value in those patients who had developed their second primary tumor 3 years after the first tumor (0.97 ± 0.24; n = 10) compared with early second primary tumor patients (0.69 ± 0.09; n = 9). Conditional on a more than 3-year second primary tumor-free survival (n = 38), there is a significantly (log-rank, P = 0.036) higher probability of a second primary tumor for mutagen-sensitive patients [relative risk, 7.8 (95% confidence interval, 0.99- 61.74; P = 0.05)]. Mutagen sensitivity is a potentional biomarker for the occurrence of ‘late’ second malignancies (>3 years between tumors), and additional studies on the inclusion of this biomarker in chemoprevention trials is commendable because it would greatly improve their efficiency.

	Introduction

Top Abstract Introduction Materials and Methods Results Discussion References

 
HNSCC³ accounts for 5% of all of the cancers in the western world. Well-known risk factors are tobacco smoking and alcohol abuse (1) . It has been established that besides these exogenous risk factors, an intrinsic susceptibility to carcinogenic assaults also plays an important role. Mutagen sensitivity is one of those intrinsic biomarkers, which measures chromatid breaks in cultured peripheral blood lymphocytes after in vitro exposure to bleomycin. Several retrospective studies have revealed the importance of the inclusion of mutagen sensitivity for cancer risk estimation, especially in combination with exposure to tobacco smoke and alcohol use (2 , 3) . It has already been established that the mean number of chromatid b/c itself is not influenced by nonconstitutional risk factors such as age, gender, smoking, and alcohol intake of the subject. Moreover, we have provided evidence that mutagen sensitivity is an inherited characteristic (4) .

HNSCC patients with small tumors can be curatively treated with surgery or radiotherapy. Although treatment strategies have greatly been improved, leading to better local tumor control, the overall survival of this patient group has not increased accordingly. This can partly be explained by the occurrence of a SPT which is not related to the treatment of the first tumor. HNSCC patients have a constant risk of about 3% each year to develop SPTs, whereas 87–100% of locoregional recurrences and distant metastases occur within 3 years (5) . A SPT usually implies a poor prognosis because it often occurs at notoriously bad sites such as the esophagus or lungs or within previously treated areas within the head and neck, defying effective treatment.

Because early detection techniques are not available yet, it is required to focus on the population at the highest risk for SPTs and, therefore, investigate new methods to identify these high risk individuals. They can then be submitted to a more intense follow-up and enrolled in specific chemoprevention trials (6) .

The risk of developing SPTs is not only related to the TNM stage of the first tumor (earlier stages are more prone for SPT) but also to the age and gender of the patient (7) . Contradictory results on the effect of tobacco smoke exposure or the cessation of smoking after diagnosis of the first tumor have been reported (8 , 9) . These established risk factors are, however, not sufficient to explain all of the SPT cases. One prospective HNSCC patient trial has indicated that mutagen sensitivity may be a valuable biomarker of susceptibility to the development of multiple primary tumors (10 , 11) . Results of our previous retrospective study also suggested a particular role of mutagen hypersensitivity in HNSCC patients who had developed two or more primary tumors (12) .

In the current prospective study of HNSCC patients, we determined the predictive value of mutagen sensitivity for the development of SPTS in the respiratory and upper digestive tract.

	Materials and Methods

Top Abstract Introduction Materials and Methods Results Discussion References

 
Subjects.
During 2.5 years (1991–1993), we collected heparinized blood samples from 218 consecutive patients who were referred to our hospital with a squamous cell carcinoma in the mucosal lining of the upper aerodigestive tract. Exclusion criteria were: any other malignancies besides head and neck or synchronous (double) tumors. In earlier studies, we and others have shown that treatment has no influence on the b/c value nor on the occurrence of SPTS (11) . The only restriction is that patients should not have systemic treatment while the blood is collected because some additional damage can be expected. From 80% of both the SPT patients and the non-SPT patients, blood was drawn before radiotherapy. The patients who had had prior radiotherapy were analyzed 3 months after treatment, which has been shown not to influence the b/c score. In mid-July 1998 all of the patients’ records were examined, and those patients who had developed a SPT in the head and neck region, esophagus, or lungs (which can be grouped together by using the term respiratory and upper digestive tract) during those years were selected (n = 19). For the classification of SPTS, the criteria of Warren and Gates (13) , later modified by Hong et al. (14) , were used. These criteria require that both tumors be histologically malignant and that they be geographically separate and distinct. The possibility of metastasis of the first tumor should be eliminated. In the present study, these criteria were strictly followed and verified by an experienced ear, nose, and throat physician. Person-year of follow-up were computed from the date of initial diagnosis to the date of death or the date of last follow-up, whichever came first.

From the cohort of HNSCC patients who did not develop any second malignancy, we matched two patients to one SPT patient. Matching was performed on gender, age, tumor site, TNM stage, and smoking history (pack-years). Cumulative smoking and alcohol intake were categorized as follows: smoking as <25 or 25 pack-years (all of the subjects were (ex)smokers and one pack contains 25 cigarettes); and alcohol intake as nondrinker, <100 or 100 unit-years. Pack-years were defined as the number-of-years-smoked multiplied by the number of cigarette-packs smoked daily (assuming that one pack contains 25 cigarettes). Unit-years were calculated similarly, i.e., the number of years multiplied by the number of drinks daily (one unit is defined as one alcoholic beverage per day). The cutoff points for high and low exposures originated from earlier mutagen sensitivity studies (2 , 12) . For the selected patient group (n = 57), the mutagen sensitivity was determined from the stored slides.

Mutagen Sensitivity Assay.
At the time of blood collection, duplicate cultures were set up for each subject. Whole blood (0.5 ml) was diluted 10 times in RPMI 1640 (BioWhittaker, Walkersville, MD) with 2 mM L-glutamine (Life Technologies, Paisley, United Kingdom), 15% FCS (Hyclone, Logan, Utah), 1.5% phytohemagglutinin (Life Technologies), and 100 units/ml penicillin and streptomycin (BioWhittaker). After culturing the cells for 3 days at 37°C in 5% CO₂, they were incubated for 5 h with 30 mU/ml bleomycin (Lundbeck, Amsterdam, the Netherlands). To arrest the cells at metaphase, 100 µl of 50 µg/ml colcemid (Sigma, St. Louis, MO) was added to the cultures 1 h before harvesting. This yielded cells in metaphase that were damaged by the bleomycin in the late S-G₂ phase of the cell cycle. The RBCs were removed, and the lymphocytes were swollen in hypotonic solution (0.06 M KCl) and fixed in Carnoy’s fixative (3:1 v/v methanol:acetic acid). After dropping the cells on wet slides, the metaphase spreads were air-dried and stained with Giemsa (Merck, Darmstadt, Germany). At this stage, the slides (two per person) were stored at room temperature until matching and scoring.

Before scoring 50 metaphase spreads for the presence of chromatid breaks, the slides were coded to assure objective "blinded" screening. The mean number of b/c of the two duplicate slides (a total of 100 metaphases) was used as a measure for the individual mutagen sensitivity. As has been published previously (15) , the scoring of gaps did not influence the outcome of the assay and was omitted in investigations. Because DNA damage was introduced in late S-G₂ phase of the cell cycle, chromosome aberrations such as translocations were not present in the metaphases. Background levels of chromatid breaks without damage induction by bleomycin that had been determined in previous studies were very low (b/c values of about 0.06) and did not differ between patients and control persons. Therefore, data representing "spontaneous" breaks were not included. A second (more crude) measure of chromosomal damage was the %am calculated as the number of cells (of the 100 metaphases screened) that contained at least one break.

Statistical Analysis.
For the analysis of the results, the matching was omitted. ANOVA was performed to determine differences in continuous variables (b/c; %am; age; follow-up time) between the two patient groups. For categorized variables (gender; smoking; alcohol use; tumor stage; site; treatment; occurrence of recurrences or metastasis) frequency tables were made and the Pearson ² values were calculated. Multiple logistic regression was performed to reveal any interaction between variables. Overall survival, time to any secondary event (SPT, recurrence, or metastasis) and time to only SPT were investigated using the method of Kaplan-Meier (16) . Comparisons were made (log-rank test) between mutagen sensitive [b/c, 0.8 (approximately the mean b/c value in this study)] and mutagen-insensitive patients (b/c, <0.8) and between smokers and nonsmokers at the time of the index tumor. In addition, relative risks were calculated using a Cox proportional hazards model. All of the Ps are two-sided.

	Results

Top Abstract Introduction Materials and Methods Results Discussion References

 
Of the patients who were eligible for this study (n = 218), 19 (8.7%) developed a SPT. At the time of follow-up, 51.4% of the patients were still alive. On the basis of this number of patients, the incidence of SPT was 15.3% in 6 years. Each of these SPT patients was matched to two patients of the cohort who did not develop SPTs. The characteristics of these 19 clusters of matched patients are depicted in Table 1 . The median person-years of follow-up was 4.5 years.

No differences between SPT and control patients were found on gender, tumor site, tumor stage, and cumulative smoking (Table 2) . Mean age of SPT patients was 69.5 ± 7.5 years compared with 69.0 ± 8.5 (P = 0.85) for non-SPT patients. All of the patients had smoked before the occurrence of the first primary tumor. In the SPT group, two patients (10.5%) were non-alcohol users; in the non-SPT group of three patients (7.9%), no drinking history could be determined, and three patients (7.9%) were nonusers. Tumor stage and site were similar in both groups.

View larger version (15K): [in this window] [in a new window]   Fig. 1. Kaplan-Meier curves of probability to no development of SPT. Former smoker, those patients who stopped smoking before they were enrolled in this study at the time of the index tumor. It was not retrievable how long and how much the smokers continued to smoke after the index tumor. The difference between two groups was statistically significant (log-rank, P < 0.02).

View larger version (17K): [in this window] [in a new window]   Fig. 2. The relationship between mutagen sensitivity and the time to develop SPT. The mean number of b/c was measured in peripheral blood lymphocytes as described in "Materials and Methods." A hypersensitivity border was used of a mean b/c value of 0.8.

View larger version (13K): [in this window] [in a new window]   Fig. 3. Kaplan-Meier curves of probability to no development of SPT. Those patients were selected who were more then 3-year-SPT-free (and still living), and they were separated into hypersensitive (mean b/c 0.8; n = 22) and nonsensitive (mean b/c <0.8; n = 16) groups. The difference between the groups was statistically significant (log-rank, P < 0.05).

	Discussion

Top Abstract Introduction Materials and Methods Results Discussion References

Interestingly, it was shown that "late-SPT" patients who developed their SPT at least 3 years after the development of the index tumor had a statistically significantly higher mean b/c value compared with those who developed their SPT within 3 years. Moreover, 9 of 10 had a b/c score of 0.8. This finding can also explain the relatively high b/c score in the multiple primary tumor group of our previous retrospective patient study (12) , in which we found a significant difference compared with HNSCC patients with one tumor. That retrospective study, moreover, included patients who had had other malignancies besides SPT in the respiratory and upper digestive tract and patients who had synchronous tumors. When using the same criteria as in the current study, the SPT patients in the retrospective study had a mean number of b/c (1.06 ± 0.35; n = 11) and only one person had developed the SPT within 3 years (2.5 years), which again indicated that the late-SPT patients are the most hypersensitive.

Another interesting point is that the non-SPT patients who died before 3 years after treatment were relatively sensitive. This may indicate that some of these patients could have developed a SPT if they had lived longer.

Two theories have been proposed about the etiology of SPT: (a) a single cell is transformed and through migration (for instance, through the submucosa or lymphatic system) of daughter cells give rise to genetically related tumors with a common clonal origin (17 , 18) . Therefore, in this case, the SPT can also be considered as metastasis or recurrence. It has been reported that 87–100% of all of the locoregional recurrences and distant metastases have occurred within 3 years (5) ; and, alternatively, (b) the new tumor has developed from independent foci that evolved from exposure to the same carcinogens, such as tobacco and alcohol (19 , 20) . These latter tumors will probably be of polyclonal origin and can develop any time after the index tumor (or be present at the same time; Ref. 21 ). The aspect of a possible difference in the time period after the index tumor between the two SPT types may give clues about the clonality of the first and second tumors. To exclude the possibility that a SPT is in fact a recurrence or a metastasis, a borderline of 3 years after the index tumor may be warranted. The importance of a borderline of 3 years between the tumors for the "real" SPTs of polyclonal origin is in line with the present study. It is concluded that, conditional on a SPT-free survival of at least 3 years, a high mutagen sensitivity greatly increases the risk of developing SPT.

Neither of the hypotheses on the etiology of SPT are in contradiction of the concept of field cancerization (22) , which assumes that the whole mucous membrane is at risk for neoplasia. More studies to investigate clonal origins of SPT are now ongoing and will reveal whether there is a difference in the etiology of second malignancies (23 , 24) . It is possible that only a portion of the SPTs defined on the basis of Warren and Gates (13) are indeed independent second events, such as, probably, the late SPTs described in our present study.

On the basis of our current results, it is interesting to hypothesize that the hypersensitive patients develop a SPT by a second hit, possibly as a result of the continuation of smoking combined with their increased intrinsic susceptibility. Those patients who have a second tumor that has a different etiology or that might in fact be a recurrence or metastasis of the first tumor (early SPTs) are not mutagen-sensitive. Molecular analysis on the clonality of the tumor material, however, is needed to provide conclusive results. Further research on these molecular biomarkers and on the mechanisms underlying mutagen sensitivity should give more clues as to what brings us the best opportunity to give HNSCC patients individualized prevention strategies.

A lot of controversy exists as to the role of smoking cessation after the index tumor in regard to the risk of developing SPT (8 , 9) . Although it was not retrievable how long and how much the patients had smoked after the index tumor, it was clearly found in the present study that smoking at the time of the index tumor was a statistically significant factor for the development of SPT. This implies that primary intervention (smoking cessation) should be a major objective for preventive measures (25) .

The low specificity (0.46) of the test, limits its use to predict which patients will develop SPT. Because of the high sensitivity (0.9) of the test, mutagen sensitivity can be used to select persons who are at the highest risk for a late SPT who can be enrolled in chemoprevention trials. This will clearly increase the efficiency of these trials because about 50% of the patients will not be treated who have a relatively low risk of developing SPT. So, for the design of head and neck cancer chemoprevention trials, the inclusion of mutagen sensitivity as a biomarker is commendable.

	Footnotes

 
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ Supported by the Dutch Council of Smoking and Health.

² To whom requests for reprints should be addressed, at Department of Otolaryngology, University Hospital Vrije Universiteit, P. O. Box 7057, 1007 MB, Amsterdam, the Netherlands. Phone: 31-20-4440905; Fax: 31-20-4440983; E-mail: BJM.Braakhuis{at}azvu.nl

³ The abbreviations used are: HNSCC, head and neck squamous cell carcinoma; %am, percentage aberrant metaphases; b/c, breaks per cell; SPT, second primary tumor; TNM, tumor-node-metastasis; CI, confidence interval.

Received 9/ 1/99; revised 4/ 6/00; accepted 4/14/00.

	References

Top Abstract Introduction Materials and Methods Results Discussion References

 

1. Maier H., Dietz A., Gewelke U., Heller W. D., Weidauer H. Tobacco and alcohol and the risk of head and neck cancer. Clin. Investig., 70: 320-327, 1992.[Medline]
2. Cloos J., Spitz M. R., Schantz S. P., Hsu T. C., Zhang Z., Tobi H., Braakhuis B. J. M., Snow G. B. Genetic susceptibility to head and neck squamous cell carcinoma. J. Natl. Cancer Inst., 88: 530-535, 1996.[Abstract/Free Full Text]
3. Spitz M. R., Fueger J. J., Halabi S., Schantz S. P., Sample D., Hsu T. C. Mutagen sensitivity in upper aerodigestive tract cancer: a case-control analysis. Cancer Epidemiol. Biomark. Prev., 2: 329-333, 1993.[Abstract]
4. Cloos J., Niewenhuis E. J. C., Boomsma D. I., Kuik D. J., van der Sterre M. L. T., Arwert F., Snow G. B., Braakhuis B. J. M. Inherited susceptibility to bleomycin-induced chromatid breaks in cultured peripheral blood lymphocytes. J. Natl. Cancer Inst., 91: 1125-1130, 1999.[Abstract/Free Full Text]
5. Sturgis E. M., Miller R. H. Second primary malignancies in the head and neck cancer patient. Ann. Otol. Rhinol. Laryngol., 104: 946-954, 1995.[Medline]
6. Lippman S. M., Spitz M. R., Trizna Z., Benner S. E., Hong W. K. Epidemiology, biology, and chemoprevention of aerodigestive cancer. Cancer (Phila.), 74: 2719-2725, 1994.[Medline]
7. Day G. L., Blot W. J., Shore R. E., McLaughlin J. K., Austin D. F., Greenberg R. S., Liff J. M. Second cancers following oral and pharyngeal cancers: role of tobacco and alcohol. J. Natl. Cancer Inst., 86: 131-137, 1994.[Abstract/Free Full Text]
8. Silverman S., Gorsky M., Greenspan D. Tobacco usage in patients with head and neck carcinomas: a follow-up study on habit changes and second primary oral/oropharyngeal cancers. J. Am. Dent. Assoc., 106: 33-35, 1983.[Abstract]
9. Schottenfeld D., Gantt R. C., Wynder E. L. The role of alcohol and tobacco in multiple primary cancers of the upper digestive system, larynx, and lung: a prospective study. Prev. Med., 3: 277-293, 1974.[Medline]
10. Schantz S. P., Spitz M. R., Hsu T. C. Mutagen sensitivity in patients with head and neck cancers: a biological marker for risk of multiple primary malignancies. J. Natl. Cancer Inst., 82: 1773-1775, 1990.[Free Full Text]
11. Spitz M. R., Hoque A., Trizna Z., Schantz S. P., Amos C. I., King T. M., Bondy M. L., Hong W. K., Hsu T. C. Mutagen sensitivity as a risk factor for second malignant tumors following malignancies of the upper aerodigestive tract. J. Natl. Cancer Inst., 86: 1681-1684, 1994.[Free Full Text]
12. Cloos J., Braakhuis B. J. M., Steen I., Copper M. P., de Vries N., Nauta J. J. P., Snow G. B. Increased mutagen sensitivity in head-and-neck squamous-cell carcinoma patients, particularly those with multiple primary tumors. Int. J. Cancer, 56: 816-819, 1994.[Medline]
13. Warren S., Gates O. Multiple primary malignant tumors: a survey of the literature and a statistical study. Am. J. Cancer, 16: 1358-1414, 1932.
14. Hong W. K., Lippman S. M., Itri L. M., Karp D. D., Lee J. S., Beyers R. M., Schantz S. P., Kramer A. M., Lotan R., Peters L. J., Dimery I. W., Brown B. W., Goepfert H. Prevention of second primary tumors with isotretinoin in squamous-cell carcinoma of the head and neck. N. Engl. J. Med., 323: 795-801, 1990.[Abstract]
15. Hsu T. C. Genetic predisposition to cancer with special reference to mutagen sensitivity. In Vitro Cell. Develop. Biol., 29: 591-603, 1987.
16. Kaplan E. L., Meier P. Nonparametric estimation from incomplete observation. J. Am. Stat. Assoc., 53: 457-481, 1958.
17. Barsky S. H., Roth M. D., Kleerup E. C., Simmons M., Tashkin D. P. Histopatholgical and molecular alterations in bronchial epithelium in habitual smokers of marijuana, cocaine, and/or tobacco. J. Natl. Cancer Inst., 90: 1182-1184, 1998.[Free Full Text]
18. Chung K. Y., Mukhopadhyay T., Kim J., Casson A., Ro J. Y., Goepfert H., Hong W. K., Roth J. A. Discordant p53 gene mutations in primary head and neck cancers and corresponding second primary cancers of the upper aerodigestive tract. Cancer Res., 53: 1676-1683, 1993.[Abstract/Free Full Text]
19. Bedi G. C., Westra W. H., Gabrielson E., Koch W., Sidransky D. Multiple head and neck tumors: Evidence of a common clonal origin. Cancer Res., 56: 2484-2487, 1996.[Abstract/Free Full Text]
20. Carey T. E. Field cancerization: are multiple cancers monoclonal or polyclonal?. Ann. Med., 28: 183-188, 1996.[Medline]
21. Scholes A. G., Woolgar J. A., Boyle M. A., Brown J. S., Vaughan E. D., Hart C. A., Jones S. A. Synchronous oral carcinomas: independent or common origin?. Cancer Res., 58: 2003-2006, 1998.[Abstract/Free Full Text]
22. Slaughter D. P., Southwick H. W., Smejkal W. "Field cancerization" in oral stratified squamous epithelium. Cancer (Phila.), 6: 963-968, 1953.[Medline]
23. Leong P. P., Rezai B., Koch W. M., Reed A., Eisele D., Lee D. J., Sidransky D., Jen J., Westra W. H. Distinguishing second primary tumors from lung metastasis in patients with head and neck squamous cell carcinoma. J. Natl. Cancer Inst., 90: 972-977, 1998.[Abstract/Free Full Text]
24. Papadimitrakopoulou V. A., Shin D. M., Hong W. K. Molecular and cellular biomarkers for field cancerization and multistep process in head and neck tumorigenesis. Cancer Metastasis Rev., 15: 63-76, 1996.
25. Cinciripini P. M., Hecht S. S., Henningfield J. E., Manley M. W., Kramer B. S. Tobacco addiction: implications for treatment and cancer prevention. J. Natl. Cancer Inst., 89: 1852-1867, 1997.[Abstract/Free Full Text]

This article has been cited by other articles:

				D. L. Chao, C. C. Maley, X. Wu, D. C. Farrow, P. C. Galipeau, C. A. Sanchez, T. G. Paulson, P. S. Rabinovitch, B. J. Reid, M. R. Spitz, et al. Mutagen Sensitivity and Neoplastic Progression in Patients with Barrett's Esophagus: A Prospective Analysis. Cancer Epidemiol. Biomarkers Prev., October 1, 2006; 15(10): 1935 - 1940. [Abstract] [Full Text] [PDF]

				E. Erdei, S.-J. Lee, Q. Wei, L.-E. Wang, Y.-S. Song, D. Bovbjerg, and M. Berwick Reliability of mutagen sensitivity assay: an inter-laboratory comparison Mutagenesis, July 1, 2006; 21(4): 261 - 264. [Abstract] [Full Text] [PDF]

				E. H.C. Dirksen, J. Cloos, B. J.M. Braakhuis, R. H. Brakenhoff, A. J.R. Heck, and M. Slijper Human Lymphoblastoid Proteome Analysis Reveals a Role for the Inhibitor of Acetyltransferases Complex in DNA Double-Strand Break Response Cancer Res., February 1, 2006; 66(3): 1473 - 1480. [Abstract] [Full Text] [PDF]

				J. Cloos, W. P.H. de Boer, M. H.J. Snel, P. van den IJssel, B. Ylstra, C. R. Leemans, R. H. Brakenhoff, and B. J.M. Braakhuis Microarray Analysis of Bleomycin-Exposed Lymphoblastoid Cells for Identifying Cancer Susceptibility Genes Mol. Cancer Res., February 1, 2006; 4(2): 71 - 77. [Abstract] [Full Text] [PDF]

				E. Kowalska, S. A. Narod, T. Huzarski, S. Zajaczek, J. Huzarska, B. Gorski, and J. Lubinski Increased Rates of Chromosome Breakage in BRCA1 Carriers Are Normalized by Oral Selenium Supplementation Cancer Epidemiol. Biomarkers Prev., May 1, 2005; 14(5): 1302 - 1306. [Abstract] [Full Text] [PDF]

				B. J. M. Braakhuis, M. P. Tabor, J. A. Kummer, C. R. Leemans, and R. H. Brakenhoff A Genetic Explanation of Slaughter's Concept of Field Cancerization: Evidence and Clinical Implications Cancer Res., April 15, 2003; 63(8): 1727 - 1730. [Abstract] [Full Text] [PDF]

				M. P. Tabor, R. H. Brakenhoff, H. J. Ruijter-Schippers, J. E. van der Wal, G. B. Snow, C. R. Leemans, and B. J. M. Braakhuis Multiple Head and Neck Tumors Frequently Originate from a Single Preneoplastic Lesion Am. J. Pathol., September 1, 2002; 161(3): 1051 - 1060. [Abstract] [Full Text] [PDF]

				M. L. Bondy, L.-E. Wang, R. El-Zein, M. de Andrade, M. S. Selvan, J. M. Bruner, V. A. Levin, W. K. Alfred Yung, P. Adatto, and Q. Wei {gamma}-Radiation Sensitivity and Risk of Glioma J Natl Cancer Inst, October 17, 2001; 93(20): 1553 - 1557. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cloos, J. Articles by Braakhuis, B. J. M. Search for Related Content PubMed PubMed Citation Articles by Cloos, J. Articles by Braakhuis, B. J. M.