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 Partridge, M. Articles by Langdon, J. D. Search for Related Content PubMed PubMed Citation Articles by Partridge, M. Articles by Langdon, J. D.

A Case-Control Study Confirms That Microsatellite Assay Can Identify Patients at Risk of Developing Oral Squamous Cell Carcinoma within a Field of Cancerization¹

Maxillofacial Unit/Oncology. King’s College Hospital, London, SE5 8RX [M. P., S. P., E. P., G. G. E., J. D. L.], and Royal Marsden NHS Trust, London, SW3 6JJ [R. P. A.], United Kingdom

	ABSTRACT

Top ABSTRACT INTRODUCTION PATIENTS AND METHODS RESULTS DISCUSSION REFERENCES

 
Distinguishing true precursor lesions on the basis of clinical or histological features alone is unreliable but is important so that appropriate intervention can be instigated. Preliminary studies have shown that a microsatellite assay may provide important new prognostic information. To build on these observations, we have performed a case-control study to establish whether we can be confident about incorporating this new information into clinical practice. We have determined the frequency of allelic imbalance (AI) within key chromosomal regions, by matching 39 cases with dysplastic oral lesions that developed a tumor on the same side of the mouth, for as many variables as possible, with controls presenting with similar lesions that did not progress to malignancy when followed for the same period. Our findings confirm that the group that developed tumor had precursor lesions that harbor AI at more loci (P = 0.002). However, no consistent patterns of AI were associated with the three grades of dysplasia: mild, moderate, and severe. One-third of the tumors developed at the same site as the dysplastic lesion and two-thirds at a different site, which revealed that the presence of these aberrations in a dysplastic lesion provided information about the risk of malignant change within a larger field. This suggests that the process of field cancerization is more widespread than previously recognized. On the basis of these findings, we advocate complete excision of all suspicious areas that show AI at two or more key loci, regardless of the degree of dysplasia. However, because the remaining mucosa is also "at risk," these cases should also be targeted to receive dietary advice and chemoprevention, to minimize their risk of tumor formation at a distant site.

	INTRODUCTION

Top ABSTRACT INTRODUCTION PATIENTS AND METHODS RESULTS DISCUSSION REFERENCES

 
There is good evidence that a proportion of white lesions that develop in the oral cavity are potentially malignant. Their premalignant potential was first documented by Paget in 1870 (1) , and the term "leukoplakia" was described by Schwimmer in 1877 (1) . Leukoplakia is now used to refer to a wide range of white oral lesions that cannot be rubbed off or diagnosed as another specific disease entity (2) . Most leukoplakias are benign, with no evidence of dysplasia (3) and no predisposition to malignancy. However, biopsy is indicated to identify the remaining 10–36% that are either dysplasia or carcinoma at initial biopsy, or will become malignant over time (4–6) . Erythroplakia is defined as a bright red, velvety area that cannot be characterized clinically or pathologically as any other condition. This condition is much rarer than leukoplakia but shows a much higher risk of malignant transformation (7) .

The clinical appearance of these lesions and the recognized risk factors for oral cancer, which include heavy smoking and high alcohol consumption, are poorly predictive for risk of tumor development, such that lesions that will ultimately become neoplastic cannot be readily identified by clinical findings and examination alone. Thus, at present, assessment of the likely behavior of precancerous lesions relies on clinical intuition and microscopic evaluation of sections of biopsies of suspicious areas stained with H&E. There is general agreement that the degree of atypia and other structural alterations can be classified as mild, moderate, or severe, and this is normally taken to indicate low, medium, or high risk of progression to malignancy (8–10) . However, the presence of dysplasia is not a reliable predictor of malignant transformation, and its absence does not mean that the patient is not at risk of developing a tumor. For example, 15% of patients with areas of leukoplakia that did not contain dysplastic features developed oral carcinoma in the study reported by Silverman et al. (5) . Histological assessment is also unreliable as a result of the subjectivity inherent in this approach and in the different histological criteria used to define dysplasia in different centers.

Because of the lack of objective criteria for defining lesions "at risk," most clinicians biopsy all suspicious red and white patches, treating only those showing severe dysplasia to avoid the risk of transformation to malignancy. The lesions selected for biopsy include those that arise in the absence of obvious traumatic factors, that occur in patients with high alcohol and tobacco consumption, that are present as areas of erythroplakia, or that are present at high-risk sites, which include the lateral border of the tongue, fauces, floor of the mouth, and ventral surface of the tongue, particularly in young females. However, most carcinomas are thought to arise in clinically normal mucosa, and the management of lesions showing only mild or moderate dysplasia remains problematical, especially when an incisional biopsy leaves histologically abnormal mucosa at the margins. Because the decision as to whether or not to treat patients with leukoplakia and erythroplakia is based on clinical factors and the severity of the dysplasia, it would be helpful to have additional molecular markers that can be used for cancer-risk assessment. Individuals recognized to be at risk can then be targeted to ensure that they limit their exposure to risk factors, are monitored regularly, and undergo excisional biopsy or laser ablation of precancerous lesions. These patients are also the group most likely to benefit from dietary advice and recruitment to chemoprevention studies, to minimize the risk of transformation of additional areas of premalignant mucosa that may be present within the field of cancerization.

The carcinogenic process involves progressive accumulation of genetic abnormalities (11) . Research over the last decade has also revealed that preneoplastic lesions show a plethora of genetic aberrations, including deletion of key chromosomal regions at 3p, 4q, 8p, 9p, 13q, and 18q (for examples, see Refs. 12–16 ), polysomy (17) , and amplification of cyclin genes (18) . Mutations and LOH³ affecting the p53 gene may also be present (19, 20) and may allow cells with damaged DNA to continue to proliferate, because these mutations remove essential cell cycle controls. p53 mutations may also influence the rate at which cells harboring genetic aberrations accumulate additional genetic events, such that when a critical threshold of aberrations is reached, cancer results (20) . Assessment of the number of aberrations or "hits" present in oral precancer by molecular profiling from biopsy tissue has been shown to supplement histological assessment and to help identify patients with lesions that may recur or progress to malignancy (13, 20–22) .

Our previous studies have shown that patients with potentially malignant lesions showing AI at two or more critical loci have a 75% greater chance of developing a tumor over 5 years (20) . To build on these preliminary observations, we have used microsatellite assay to conduct a case-control study, matching patients with dysplastic lesions who subsequently developed SCC on the same side of the mouth with a group of patients with similar lesions who did not develop tumor when followed for the same period. Each case progressing to malignancy was matched with a control of the same sex, age, and similar exposure to risk factors to control for variables that would be expected to increase the number of random events detected in the lesions examined.

	PATIENTS AND METHODS

Top ABSTRACT INTRODUCTION PATIENTS AND METHODS RESULTS DISCUSSION REFERENCES

 
Thirty-two cases presenting with single areas of leukoplakia or erythroplakia with histological evidence of dysplasia in which SCC developed on the same side of the mouth were identified retrospectively by the examination of case notes. An additional seven cases were identified when they indicated that they had a previous biopsy carried out at another Center many years before treatment of a malignant lesion. Paraffin-embedded blocks were retrieved for the cases identified, and tissue from prospective cases was snap-frozen in liquid nitrogen immediately after biopsy and stored at -70°C. Venous blood was collected from all of the living patients and stored in NaCl-EDTA tubes and kept at -20°C until required.

Controls for each case of dysplasia developing oral SCC were matched for age, sex, site, grade of dysplasia, smoking and alcohol habits, and the status of the margins. The status of the margins was established by examination of the sections available at the time of primary diagnosis. No additional sections were prepared for analysis, because of the limited amount of material available. Only cases developing SCC at least 30 months after the diagnosis of dysplasia were included, to avoid analyzing lesions at the margins of a developing tumor. When multiple biopsies were available (cases 4 and 17), only the initial lesion was analyzed. In every case, the control was selected from the pathology archives at the hospital at which the dysplastic lesion was identified, so that the microscopic features of both the case and control were reported by the same pathologist. Particular care was taken to match the length of time of follow-up because, if test cases were matched with controls that did not progress for long periods, selecting cases with a good prognosis might unfairly maximize the differences between the test and control groups. Thus, a maximum of 12 months variance was allowed for matching. For example, if a case progressed to malignancy at 36 months, the control was a patient who was tumor-free at 36 months but had not been followed for more than 48 months. This protocol avoided a comparison of patients with dysplastic lesions who developed cancer with an early disease-free control group, but did not take into account the fact that the time period over which dysplastic lesions progressed to malignancy is currently unknown, such that this approach might not reflect the true natural history of this disease. The clinical features and risk factors of the lesions studied are summarized in Table 1 . The median time of follow-up of the patients was 59 months (range, 15–120 months).

PCR primers for the polymorphic microsatellite markers were obtained from Research Genetics (Huntsville, Alabama) or synthesized locally. One of the primers was end-labeled with [-³²P]ATP, and PCR products were generated from standard reactions. Microsatellite markers were chosen within the five candidate tumor suppressor gene areas identified at 3p (24) and including loci that have shown a high frequency of AI in previous studies (13, 16, 20, 24) . Products were separated by gel electrophoresis in denaturing 6% polyacrylamide-7M urea and autoradiographed overnight. Labeled pBR322 was included as a sequencing ladder to facilitate sizing of the alleles. Cases were scored by visual inspection of band patterns and were considered to show AI if the ratio of the two alleles in the tumor was 50% less than that detected for the normal sample. Novel microsatellite alleles were identified by the presence of bands that were absent in the normal sample; these cases were scored as showing msi and were excluded from the informative cases. The chromosomal location of the RFLP markers and microsatellites used is shown in Table 2 .

Loci showing msi were evaluated in a similar way, with loci showing AI being noninformative, or not done, omitted. Each available locus was scored as 1 (case msi; control ROH), -1 (control msi; case ROH), or 0 (case and control both ROH or msi).

To ascertain whether aberrations at specific chromosomal regions were associated with the grade of dysplasia (mild, moderate, or severe) or with smoking or alcohol habits, the AI scores were calculated by combining the scores for the loci examined with the five key regions at 3p 8p21–23, 9p13–24, and 13q13–31 to avoid multiple significance testing. The five key regions identified at 3p were defined by the following markers: 3p24.3–26.5 (D3S192, D3S1259); 3p21.3–22.1 (D3S686); 3p21.1–21.32 (D3S32, D3S1573, D3S1241); 3p14.3 (D3S4103); 3p13 (D3S659, D3S1562, D3S30). The markers that were combined at 8p21.1–23.3, 9p13–24, and 13q14–31 were D8S264, LPL, D8S298, D8S133; D9S286, IFN-, D9S171, D9S161, D9S43; and Rb, D13S125, respectively.

The relationship between the AI score and the severity of dysplasia, smoking, and alcohol consumption was investigated by testing the significance of the correlation between the AI score and these clinicopathological parameters. Correlations in the order of only 0.7 or above could reliably be detected when 39 case/control pairs are analyzed. The Kruskal-Wallis test was used to compare the two groups.

	RESULTS

Top ABSTRACT INTRODUCTION PATIENTS AND METHODS RESULTS DISCUSSION REFERENCES

 
Table 1 lists the cases analyzed and relevant clinical information. Sixteen lesions with evidence of mild dysplasia, 15 with moderate, and 8 showing severe dysplastic changes were identified for study. The mean time interval between the recognition of dysplasia and the development of oral SCC was 58 months (range, 15–110 months). Fourteen cases developed a tumor at the same site as the dysplastic lesion, 19 tumors appeared at adjacent sites (e.g., dysplasia, buccal mucosa, and tumor on the alveolus), and 6 malignant lesions developed at distant sites in the oral cavity. After the initial biopsy, 11 dysplastic lesions were reported as being excised with clear margins whereas 28 samples had evidence of hyperplasia or dysplasia at one or more mucosal margins.

The results obtained after application of microsatellite assay are summarized in Tables 1 and 2 , and representative cases are shown in Fig. 1 . The frequency of AI at the loci tested ranged from 0 to 37.5%, with the highest levels observed for p53 (32%), DCC (37.5%), and IFN- (35%). msi at one or more loci was found for 19 cases. Thirty-seven of 39 dysplastic lesions analyzed for cases that developed a tumor, and 16 cases with lesions that did not progress, showed AI at two or more informative loci. AI generally involved single microsatellites, although some lesions showed deletion at adjacent markers, which suggested loss of large chromosomal regions (for examples, see cases 18, 24, and 38 and controls 31, 35, and 37 in Table 1 ).

View larger version (25K): [in this window] [in a new window]   Fig. 1. Representative examples of microsatellites used. Arrows, cases showing AI.

The data were analyzed to assess whether AI at individual loci, or within the chromosomal regions examined (see "Patients and Methods" section), were associated with tumor development. The only statistically significant relationship found was that AI at p53 occurred at an increased frequency when the cases with dysplastic lesions that developed a tumor and the matched controls were compared (17 cases and 3 controls showed AI at this locus; P = 0.006).

Evidence of a relationship between the number of assessable loci showing AI, or any specific or pattern of aberration, and the grade of dysplasia was also sought (see Table 3 A), but none was found. If there were an association with the number of assessable loci, the median AI score should be higher when the groups with mild and severe dysplasia are compared however, in the present study, this score was lower for the group with severe dysplasia, which may reflect the small numbers of severely dysplastic lesions examined to date. Detailed analysis reveals that some loci did show a higher percentage of AI when the findings for severe dysplasia were compared with those for mild and moderate dysplasia. However, other markers showed a higher frequency of aberration for lesions showing moderate or severe dysplasia, or else showed no difference, when the three groups were compared. For example, 43% AI was found at 3p13 for severe dysplasia, whereas the frequency was 14% for moderate and 20% for mild dysplasia. The frequency of AI at 3p21.1–21.32 and 3p13–24 was broadly similar for all of the three grades of dysplasia, and the highest frequency of AI at 3p24.3–26.5 was found for mild dysplasia. However, these findings were not statistically significant, such that the variation is likely to reflect the small number of cases examined to date.

	DISCUSSION

Top ABSTRACT INTRODUCTION PATIENTS AND METHODS RESULTS DISCUSSION REFERENCES

 
Several lines of enquiry have shown that relying on clinical appearance is misleading and that histology is unreliable when trying to identify potentially malignant lesions at risk of progression [reviewed by Westra et al. (26) ]. However, molecular studies reveal that it is possible to harness new knowledge about the genetic aberrations present in precancerous lesions to identify areas of leukoplakia and erythroplakia at high risk of progression to malignancy. The study conducted by Mao et al. (13) , based on an analysis of dysplastic lesions with two microsatellite markers (one at 3p14, the other at 9p21), demonstrated that the probability of developing a tumor was 45% if AI at either of these two key chromosomal regions was detected. Our subsequent report (20) , which incorporated 18 microsatellite markers at 8 chromosome arms, revealed that a higher percentage of precursor lesions can be identified, and that the risk of tumor development within the upper aerodigestive tract at 5 years is approximately 75% when dysplastic lesions harbor AI at two or more of the key microsatellites. The present case-control study, which minimizes variation that might influence the number of loci showing AI attributable to differences in age, sex, site of the dysplastic lesion, risk factors, grade of dysplasia, and length of follow-up, was undertaken to build on these preliminary observations. Our findings confirm that patients with dysplastic lesions harboring AI at more polymorphic loci within the critical chromosomal regions develop a tumor more frequently than matched controls with lesions showing AI at fewer loci (P = 0.002). Although the dysplastic lesions may not have been precursor lesions per se, they developed in fields that harbored the genetic aberrations associated with tumorigenesis. This means that we can now be confident about using information that is derived from the frequency of AI, obtained from microsatellite assay to distinguish the benign from the more troublesome true precursor lesions or, as Sauter et al. (26) so aptly coined the phrase, "distinguish our benign pussycats from the baby tigers."

In the present study, 14 tumors developed at the same site as the dysplastic lesion, 19 developed at contiguous sites, and 6 developed at an oral site remote from the initial biopsy. Our evidence also suggests that the process of field cancerization is much more extensive than previously thought, and that the excision of lesions is likely to leave mucosa that harbors aberrations that we cannot see, inasmuch as 11 cases developed a tumor even though the dysplastic lesion was excised with clear margins. However, 26 cases had evidence of morphological change at the mucosal margins, which suggests that this altered mucosa may have been the source of cells for many of the subsequent tumors. Thus, whereas we cannot exclude the fact that some lesions that were excised in toto represent clonal outgrowths of benign cells that may never have progressed to malignancy, or that the areas of hyperplasia and dysplasia at the margins of dysplastic lesions were the source of cells for the new tumor, our findings suggest that the detection of AI within an area of leukoplakia or erythroplakia provides information about the risk of tumor development within an entire field of cancerization. Similar findings have been reported by Hittelman et al. (27) , who analyzed normal and premalignant lesions adjacent to head and neck tumors. This conclusion is supported by studies that have revealed that molecular aberrations can be detected before there is histological evidence of morphological change (28–31) . However, what remains to be answered is whether the aberrations detected in the dysplasia examined were present at other sites in the oral mucosa in which cancer developed at the time of initial biopsy, or whether they occurred because of continued exposure to carcinogens.

Six cases showed msi at two or more loci, which suggested that a subset of patients may have had defective mismatch repair. However, no aberrations affecting the hMSH2 and hMLH1 genes were detected.⁴ The observation that cases developing tumors showed more novel microsatellite alleles than did the matched controls (P = 0.002) was unexpected, but it likely reflects that these aberrations also provide an index of instability. However, they occur at only a low frequency and are unlikely to be as useful as an index based on AI in the clinic.

Overall, the percentage of lesions showing AI at the markers tested was in general agreement with previous studies (12, 20) and lower than that reported for SCC (23) . The frequency of AI at the microsatellites investigated was analyzed to determine whether specific aberrations were associated with tumorigenesis. However, only the p53 locus showed AI at a significantly higher frequency when the cases that progressed to cancer were compared with the group that did not progress.

We anticipated that we would find that most patients who developed a tumor would present with early lesions showing more severe histological changes. The cases studied in the present series are not a consecutive series; 42% of the initial lesions were reported as showing mild, 38% showed moderate, and 20% showed severe dysplasia, emphasizing that mild dysplasia is not necessarily associated with low risk of tumor development within a field "at risk." Morphologically similar lesions showed a wide range of genetic aberrations such that no specific abnormalities associated with the three grades of dysplasia were identified. However, this type of analysis is complicated by the subjectivity inherent in classifying dysplasia as mild, moderate, or severe. Thus, at the present time, additional studies are required to determine whether it is possible to relate histological changes to molecular aberrations, and whether genetic aberrations predicting risk of progression can be defined that will ultimately provide a new standard for therapeutic intervention.

In the present study, 37 of the dysplastic lesions that progressed to cancer showed AI at two or more loci, a finding that has previously been shown to be associated with high risk of tumorigenesis (20) . On the basis of the findings from this study and our previous report, we advocate complete excision of all dysplastic lesions showing AI at two or more key microsatellite markers, regardless of the degree of dysplasia, aiming to produce margins that are at least morphologically normal. Should this situation not be achieved, repeat surgery may be advisable. If this action had been taken in the present study, 16 patients with dysplastic lesions that had not progressed to tumor during the period of study would have been overtreated. Nevertheless, we cannot exclude the possibility that the control cases may still develop a malignant lesion, as we do not know the time-scale over which progression occurs. However, because a significant proportion of tumors developed at contiguous or distant sites when the initial dysplastic lesion harbored AI at two or more loci, this strongly suggests that the process of field cancerization is much more widespread than was previously thought. In view of this, patients with lesions that harbor AI at two or more key loci should be targeted to limit their exposure to risk factors and to receive dietary advice and chemoprevention. Following this regimen should minimize an individual’s risk of developing a tumor at a distant site, or locally when molecular aberrations are present in histologically normal mucosa (30) . However, it may also be prudent to carry out biopsy for molecular and histological analysis every year, to judge the effect of this preventative regimen in this high-risk group. In addition, based on the findings from this study, it seems desirable to screen clinically normal mucosa as part of the routine work-up for head and neck cancer patients by histological examination and, by using the molecular test whenever possible, to establish whether there is molecular evidence of field cancerization, to help with the overall risk assessment for these patients.

	ACKNOWLEDGMENTS

 
We acknowledge the contribution of the histopathologists from The Queen Victoria Hospital, East Grinstead; The Royal Surrey County Hospital, Guildford; St George’s Hospital, Tooting; Queen Mary’s Hospital, Roehampton; and King’s College Hospital, London, for identifying cases and reviewing the histology for this study.

	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 This research was supported by a grant from S. Thames R and D, United Kingdom.

² To whom requests for reprints should be addressed, at Maxillofacial Unit/Molecular Oncology, King’s College Hospital, Denmark Hill, London, SE5 8RX, United Kingdom.

³ The abbreviations used are: LOH, loss of heterozygosity; SCC, squamous cell carcinoma; AI, allelic imbalance; msi, microsatellite instability; ROH, retention of heterozygosity.

⁴ G. Emilion, unpublished data.

Received 10/18/99. Accepted 5/17/00.

	REFERENCES

Top ABSTRACT INTRODUCTION PATIENTS AND METHODS RESULTS DISCUSSION REFERENCES

 

1. Bouquot J. E., Whitaker S. B. Oral leukoplakia: rationale for diagnosis and prognosis of its clinical subtypes or "phases. " Quintessence Int, 25: 133-140, 1994.[Medline]
2. Kramer I. R. H., Lucas R. B., Pindborg J. J., Sobin L. H. Definition of leukoplakia and related lesions: an aid to studies on oral precancer. Oral Surg. Oral Med. Oral Pathol, 46: 518-539, 1978.[Medline]
3. Waldron A., Shafer W. G. Leukoplakia revisited: a clinicopathologic study of 3256 oral leukoplakias. Cancer (Phila.), 36: 1386-1392, 1975.[Medline]
4. MacDonald D. G. Premalignant lesions of oral epithelium Dolby A. E. eds. . Oral Mucosa in Health and Disease, : 335-369, Blackwell Scientific Publications Oxford 1975.
5. Silverman, S., Jr., Gorsky, M., and Lozada, F. Oral leukoplakia and malignant transformation: a follow-up study of 257 patients. Cancer (Phila.), 53: 563–568. 1984.
6. Lumerman H., Freedman P., Kerpel S. Oral epithelial dysplasia and the development of invasive squamous cell carcinoma. Oral Surg. Oral Med. Oral Pathol, 79: 321-329, 1995.
7. Shafer, W. G., and Waldron, C. A. Erythroplakia of the oral cavity. Cancer (Phila.), 185: 339–341. 1975.
8. Maerjer R., Burkardt A. Klinik oraler leukoplakien und prakanzerosen retrospektive studie an 200 patienten. Dtsch. Zahn Mund Kiefer Gesichtschir, 2: 206-220, 1978.
9. Kramer I. R. H. Basic histopathological features of oral premalignant lesions Mackenzie I. C. Dabelsteen E. Squier C. eds. . Oral Premalignant Lesions, : 23-24, University of Iowa Press Iowa 1980.
10. Karabulut A., Reibel J., Therkildsen M. H., Praetorius F., Nielsen H. W., Dabelsteen E. Observer variability in the histologic assessment of oral premalignant lesions. J. Oral Pathol. Med, 24: 198-200, 1995.[Medline]
11. Fearon E. R., Vogelstein B. A genetic model for colorectal tumorigenesis. Cell, 61: 759-767, 1990.[Medline]
12. Partridge M., Emilion G., Langdon J. D. LOH at 3p correlates with a poor survival in oral squamous cell carcinoma. Br. J. Cancer, 73: 366-371, 1996.[Medline]
13. Mao L., Lee J. S., Fan Y. H., Ro J. Y., Batsakis J. G., Lippman S., Hittlelman W., Hong W. K. Frequent microsatellite alterations at chromosomes 9p21 and 3p14 in oral premalignant lesions and their value in cancer risk assessment. Nat. Med, 2: 682-685, 1996.[Medline]
14. Ishwad C. S., Ferrell R. E., Rossie K. M., Appel B. N., Johnson J. T., Myers E. N., Law J. C., Srivastava S., Gollin S. M. Loss of heterozygosity on the short arm of chromosomes 3 and 9 in oral cancer. Int. J. Cancer (Predict. Oncol.), 69: 1-4, 1996.[Medline]
15. Roz L., Wu C. L., Porter S., Scully C., Speight P., Read A., Sloan P., Thakker N. Allelic imbalance on chromosome 3p in oral dysplastic lesions: an early event in oral carcinogenesis. Cancer Res, 56: 1228-1231, 1996.[Abstract/Free Full Text]
16. Wu C. L., Roz L., Sloan P., Read A. P., Holland S., Porter S., Scully C., Speight P. M., Thakker N. Deletion mapping defines three discrete areas of allelic imbalance on chromosome arm 8p in oral and oropharyngeal squamous cell carcinomas. Genes Chromosomes Cancer, 20: 347-353, 1997.[Medline]
17. Virgilio L., Shuster M., Gollin S. M., Veronese M. L., Ohta M., Huebner K., Croce C. M. FHIT gene alterations in head and neck squamous cell carcinomas. Proc. Natl. Acad. Sci. USA, 93: 9770-9775, 1996.[Abstract/Free Full Text]
18. Callender T., El-Naggar A. K., Frankenthaler R., Luna M. A., Batsakis J. G. PRAD-1 oncogene amplification in primary head and neck squamous cell carcinoma. Cancer (Phila.), 74: 152-158, 1994.[Medline]
19. Califano J., van der Riet P., Westra W., Nawroz H., Clayman G., Piantadosi S., Corio R., Lee D., Greenberg B., Koch W., Sidransky D. Genetic progression model for head and neck cancer: implications for field cancerization. Cancer Res, 56: 2488-2492, 1996.[Abstract/Free Full Text]
20. Partridge, M., Emilion, G., Pateromichelakis, S., A’Hern, R., Phillips, E., and Langdon, J. Allelic imbalance at chromosomal loci implicated in the pathogenesis of oral precancer; cumulative loss and its relationship with progression to cancer. Eur. J. Cancer, Oral Oncol., 34: 77–83, 1998.
21. El-Naggar A. K., Lee M. S., Wang G., Luna M. A., Goepfert H., Batsakis J. G. Sequential loss of heterozygosity at microsatellite motifs in preinvasive and invasive head and neck squamous carcinoma. Cancer Res, 55: 2656-2659, 1995.[Abstract/Free Full Text]
22. Emilion G., Langdon J. D., Speight P., Partridge M. Frequent gene deletions in potentially malignant oral lesions. Br. J. Cancer, 73: 809-813, 1996.[Medline]
23. Partridge M., Emilion G., Falworth M., A’Hern R., Phillips E., Pateromichelakis S., Langdon J. Patient-specific mutation databases for oral cancer. Int. J. Cancer (Predict. Oncol.), 84: 284-292, 1999.[Medline]
24. Papadimitrakopoulou V., Izzo J., Lippman S. M., Lee J. S., Fan Y. H., Clayman G., Ro J. Y., Hittelman W. N., Lotan R., Hong W. K., Mao L. Frequent inactivation of p16^INK4a in oral premalignant lesions. Oncogene, 14: 1799-1803, 1997.[Medline]
25. Wistuba I. I., Lam S., Behrens C., Virmani A. K., Fong K. M., LeRiche J., Samet J. M., Srivastava S., Minna J. D., Gazdar A. F. Molecular damage in the bronchial epithelium of current and former smokers. J. Natl. Cancer Inst, 89: 1366-1373, 1997.[Abstract/Free Full Text]
26. Sauter G., Mihatsch M. J. Pussycats and baby tigers: non-invasive (pTa) and minimally invasive (pT1) bladder carcinomas are not the same! J. Pathol, 185: 339-341, 1998.[Medline]
27. Hittelman, W. N., Kim, H. J., Lee, J. S., Shin, D. M., Lippman, S. M., Kim, J., Ro, J. Y., and Hong, W. K. Detection of chromosome instability of tissue fields at risk: in situ hybridization. J. Cell. Biochem., S25: 57–62, 1996.
28. Hung J., Kishimoto Y., Sugio K., Virmani A., McIntire D. D., Minna J. D., Gazdar A. F. Allele-specific chromosome 3p deletions occur at an early stage in the pathogenesis of lung carcinoma. J. Am. Med. Assoc, 273: 366-1373, 1995.[Medline]
29. Franklin W. A., Gadar A. F., Haney J., Wistuba I. I., La Rosa F. G., Kennedy T., Ritchey D. M., Miller Y. E. Widely dispersed p53 mutations in respiratory epithelium. A novel mechanism for field carcinogenesis. J. Clin. Investig, 100: 2133-2137, 1997.[Medline]
30. Mao L., El-Naggar A. K., Papadimitrakopoulou V., Shin D. M., Shin H. C., Fan Y. H., Zhou X., Clayman G., Lee J. J., Lee J. S., Hittelman W. N., Lippman S. M., Hong W. K. Phenotype and genotype of advanced premalignant head and neck lesions after chemopreventive therapy. J. Natl. Cancer Inst, 90: 1545-1551, 1998.[Abstract/Free Full Text]
31. Partridge, M., Pateromichelakis, S., Tesfa-Selase, F., Li, S-R., Phillips, E., Huang, X-H., and Langdon, J. D. Detection of minimal residual cancer to investigate why tumors recur despite seemingly adequate treatment. Clin. Cancer Res., in press, 2000.

This article has been cited by other articles:

				H. Kawaguchi, A. K. El-Naggar, V. Papadimitrakopoulou, H. Ren, Y.-H. Fan, L. Feng, J. J. Lee, E. Kim, W. K. Hong, S. M. Lippman, et al. Podoplanin: A Novel Marker for Oral Cancer Risk in Patients With Oral Premalignancy J. Clin. Oncol., January 20, 2008; 26(3): 354 - 360. [Abstract] [Full Text] [PDF]

				W. N. William Jr. and V. A. Papadimitrakopoulou Identification of High-risk Cohorts for Head and Neck Cancer Prevention Based on Tissue Markers LOH and cyclin D1 ASCO Educational Book, January 1, 2008; 2008(1): 66 - 68. [Abstract] [Full Text] [PDF]

				X. Huang, S. Pateromichelakis, A. Hills, M. Sherriff, A. Lyons, J. Langdon, E. Odell, P. Morgan, J. Harrison, and M. Partridge p53 Mutations in Deep Tissues Are More Strongly Associated with Recurrence than Mutation-Positive Mucosal Margins Clin. Cancer Res., October 15, 2007; 13(20): 6099 - 6106. [Abstract] [Full Text] [PDF]

				K. Gaballah, A. Hills, D. Curiel, G. Hallden, P. Harrison, and M. Partridge Lysis of Dysplastic but not Normal Oral Keratinocytes and Tissue-Engineered Epithelia with Conditionally Replicating Adenoviruses Cancer Res., August 1, 2007; 67(15): 7284 - 7294. [Abstract] [Full Text] [PDF]

				C. F. Poh, L. Zhang, D. W. Anderson, J. S. Durham, P. M. Williams, R. W. Priddy, K. W. Berean, S. Ng, O. L. Tseng, C. MacAulay, et al. Fluorescence Visualization Detection of Field Alterations in Tumor Margins of Oral Cancer Patients. Clin. Cancer Res., November 15, 2006; 12(22): 6716 - 6722. [Abstract] [Full Text] [PDF]

				B. W. Neville, A. C. Chi, and M. Jeter A red lesion on the palate. J Am Dent Assoc, November 1, 2006; 137(11): 1537 - 1538. [Full Text] [PDF]

				G. J. Kelloff, S. M. Lippman, A. J. Dannenberg, C. C. Sigman, H. L. Pearce, B. J. Reid, E. Szabo, V. C. Jordan, M. R. Spitz, G. B. Mills, et al. Progress in Chemoprevention Drug Development: The Promise of Molecular Biomarkers for Prevention of Intraepithelial Neoplasia and Cancer--A Plan to Move Forward Clin. Cancer Res., June 15, 2006; 12(12): 3661 - 3697. [Abstract] [Full Text] [PDF]

				S. M. Lippman and J. J. Lee Reducing the "Risk" of Chemoprevention: Defining and Targeting High Risk--2005 AACR Cancer Research and Prevention Foundation Award Lecture. Cancer Res., March 15, 2006; 66(6): 2893 - 2903. [Abstract] [Full Text] [PDF]

				L. Zhang, M. Williams, C. F. Poh, D. Laronde, J. B. Epstein, S. Durham, H. Nakamura, K. Berean, A. Hovan, N. D. Le, et al. Toluidine Blue Staining Identifies High-Risk Primary Oral Premalignant Lesions with Poor Outcome Cancer Res., September 1, 2005; 65(17): 8017 - 8021. [Abstract] [Full Text] [PDF]

				S. M. Lippman, J. Sudbo, and W. K. Hong Oral Cancer Prevention and the Evolution of Molecular-Targeted Drug Development J. Clin. Oncol., January 10, 2005; 23(2): 346 - 356. [Abstract] [Full Text] [PDF]

				D. L. Ellsworth, R. E. Ellsworth, B. Love, B. Deyarmin, S. M. Lubert, V. Mittal, J. A. Hooke, and C. D. Shriver Outer Breast Quadrants Demonstrate Increased Levels of Genomic Instability Ann. Surg. Oncol., September 1, 2004; 11(9): 861 - 868. [Abstract] [Full Text] [PDF]

				B. J. M. Braakhuis, P. J. F. Snijders, W.-J. H. Keune, C. J. L. M. Meijer, H. J. Ruijter-Schippers, C. R. Leemans, and R. H. Brakenhoff Genetic Patterns in Head and Neck Cancers That Contain or Lack Transcriptionally Active Human Papillomavirus J Natl Cancer Inst, July 7, 2004; 96(13): 998 - 1006. [Abstract] [Full Text] [PDF]

				M. P. Tabor, R. H. Brakenhoff, H. J. Ruijter-Schippers, J. A. Kummer, C. R. Leemans, and B. J. M. Braakhuis Genetically Altered Fields as Origin of Locally Recurrent Head and Neck Cancer: A Retrospective Study Clin. Cancer Res., June 1, 2004; 10(11): 3607 - 3613. [Abstract] [Full Text] [PDF]

				J. Sudbo, S. M. Lippman, J. J. Lee, L. Mao, W. Kildal, A. Sudbo, S. Sagen, M. Bryne, A. El-Naggar, B. Risberg, et al. The Influence of Resection and Aneuploidy on Mortality in Oral Leukoplakia N. Engl. J. Med., April 1, 2004; 350(14): 1405 - 1413. [Abstract] [Full Text] [PDF]

				Q.-T. Le and A. J. Giaccia Therapeutic Exploitation of the Physiological and Molecular Genetic Alterations in Head and Neck Cancer Clin. Cancer Res., October 1, 2003; 9(12): 4287 - 4295. [Abstract] [Full Text] [PDF]

				P. K. Ha and J. A. Califano THE MOLECULAR BIOLOGY OF MUCOSAL FIELD CANCERIZATION OF THE HEAD AND NECK Crit. Rev. Oral. Biol. Med., September 1, 2003; 14(5): 363 - 369. [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]

				J. Reibel PROGNOSISOF ORAL PRE-MALIGNANT LESIONS: SIGNIFICANCEOF CLINICAL, HISTOPATHOLOGICAL, AND MOLECULAR BIOLOGICAL CHARACTERISTICS Crit. Rev. Oral. Biol. Med., January 1, 2003; 14(1): 47 - 62. [Abstract] [Full Text]

				M. P. Rosin, W. L. Lam, C. Poh, N. D. Le, R. J. Li, T. Zeng, R. Priddy, and L. Zhang 3p14 and 9p21 Loss Is a Simple Tool for Predicting Second Oral Malignancy at Previously Treated Oral Cancer Sites Cancer Res., November 15, 2002; 62(22): 6447 - 6450. [Abstract] [Full Text] [PDF]

				A. Forastiere, W. Koch, A. Trotti, and D. Sidransky Head and Neck Cancer N. Engl. J. Med., December 27, 2001; 345(26): 1890 - 1900. [Full Text] [PDF]

				M. Partridge, S. Pateromichelakis, E. Phillips, G. Emilion, and J. Langdon Profiling Clonality and Progression in Multiple Premalignant and Malignant Oral Lesions Identifies a Subgroup of Cases with a Distinct Presentation of Squamous Cell Carcinoma Clin. Cancer Res., July 1, 2001; 7(7): 1860 - 1866. [Abstract] [Full Text] [PDF]

				Z. Guo, K. Yamaguchi, M. Sanchez-Cespedes, W. H. Westra, W. M. Koch, and D. Sidransky Allelic Losses in OraTest-directed Biopsies of Patients with Prior Upper Aerodigestive Tract Malignancy Clin. Cancer Res., July 1, 2001; 7(7): 1963 - 1968. [Abstract] [Full Text] [PDF]

				S. M. Lippman and W. K. Hong Molecular Markers of the Risk of Oral Cancer N. Engl. J. Med., April 26, 2001; 344(17): 1323 - 1326. [Full Text] [PDF]

				W. K. Hong, M. R. Spitz, and S. M. Lippman Cancer Chemoprevention in the 21st Century: Genetics, Risk Modeling, and Molecular Targets J. Clin. Oncol., November 1, 2000; 18(90001): 9s - 18. [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