Human papillomavirus (HPV) status of non-tobacco related squamous cell carcinomas of the lateral tongue.

OBJECTIVES: The human papillomavirus (HPV) is an important cause of some head and neck squamous cell carcinomas (HNSCCs), but its role in cancer of the lateral tongue is debatable. Suspicion of HPV causation is heightened when these lateral tongue carcinomas arise in patients that are young and/or have never smoked. The purpose of this study was to determine the incidence of transcriptionally active high risk HPV in these tumors, with a particular emphasis on non-smoking patients who are often presumed to have HPV-positive tumors. METHODS: We evaluated 78 HNSCCs of the lateral tongue for the presence of HPV using p16 immunohistochemistry and an RNA in situ hybridization assay targeting HPV E6/E7 mRNA. The study population was enriched for patients without traditional risk factors such as smoking and drinking. RESULTS: P16 overexpression was detected in 9 (11.5%) of 78 cases, but HPV E6/E7 mRNA transcripts were detected in only 1 (1.3%) case (positive predictive value of p16 staining for the presence of transcriptionally active HPV=0.12). HPV mRNA transcripts were not detected in any patient under 40 (n=11), or in patients who had never smoked (n=44), had quit smoking (n=15), and/or were only light consumers of alcohol (n=57). CONCLUSIONS: HPV is not detected in the vast majority of lateral tongue carcinomas. In light of the observation that HPV plays little if any role in the development of these cancers, routine HPV testing is unwarranted , even for patients without traditional risk factors. P16 staining is not a reliable marker for the presence of transcriptionally active HPV at this particular anatomic site.

Detection of Merkel cell virus and correlation with histologic presence of Merkel cell carcinoma in sentinel lymph nodes.

BACKGROUND: Adjuvant treatment can dramatically improve the survival of patients with metastatic Merkel cell carcinoma (MCC), making early, accurate detection of nodal disease critical. The purpose of this study was to correlate Merkel cell virus (MCV) detection with histopathologic disease in sentinel lymph nodes (SLNs) of MCC. METHODS: Merkel cell carcinoma cases with SLN (n=25) were compared with negative controls (n=27). Viral load was obtained by quantitative polymerase chain reaction (PCR) for regions VP1 and LT3 of MCV. Histopathologic disease and viral load were correlated. RESULTS: Merkel cell virus was detected in 16 out of 17 (94%) of primary MCC (mean viral load (MVL)=1.44 copies per genome). Viral load in the negative controls was <0.01 copies per genome. Merkel cell carcinoma was present in 5 out of 25 (20%) SLN by histopathology, and MCV was detected in 11 out of 25 (44%) MCC SLN (MVL=1.68 copies per genome). In all, 15 out of 25 (60%) SLN showed correlation between histologic and MCV results. In all, 2 out of 25 (8%) samples were histopathologically positive and PCR negative. Of note, 8 out of 25 (32%) samples had detectable MCV without microscopic disease. CONCLUSION: Patients with positive SLN for MCV even if negative by histopathology were identified. The application of molecular techniques to detect subhistologic disease in SLN of MCC patients may identify a subset of patients who would benefit from adjuvant nodal treatment.

Identification of a mononucleotide repeat as a major target for mitochondrial DNA alterations in human tumors.

Mitochondrial DNA (mtDNA) mutations scattered through coding and noncoding regions have been reported in cancer. The mechanisms that generate such mutations and the importance of mtDNA mutations in tumor development are still not clear. Here we present the identification of a specific and highly polymorphic homopolymeric C stretch (D310), located within the displacement (D) loop, as a mutational hotspot in primary tumors. Twenty-two % of the 247 primary tumors analyzed harbored somatic deletions/insertions at this mononucleotide repeat. Moreover, these alterations were also present in head and neck preneoplastic lesions. We further characterized the D310 variants that appeared in the lung and head and neck tumors. Most of the somatic alterations found in tumors showed deletion/insertions of 1- or 2-bp generating D310 variants identical to constitutive polymorphisms described previously. Sequencing analysis of individual clones from lymphocytes revealed that patients with D310 mutations in the tumors had statistically significant higher levels of D310 heteroplasmy (more than one length variant) in the lymphocyte mtDNA as compared with the patients without D310 mutations in the tumor mtDNA. On the basis of our observations, we propose a model in which D310 alterations are already present in normal cells and achieve homoplasmy in the tumor through a restriction/amplification event attributable to random genetic drift and clonal expansion.

Allelic losses in OraTest-directed biopsies of patients with prior upper aerodigestive tract malignancy.

Genetic alterations at critical chromosome loci have been shown to be predictors of the progression of oral premalignancy-to-invasive cancer. We obtained a unique group of oral biopsies, initially collected during a prospective study designed to test the ability of OraTest (toluidine blue), to identify recurrent oral neoplastic lesions in patients with definite therapy for head and neck or upper aerodigestive tract (UADT) cancer. A total of 46 cases, including 13 squamous cell carcinoma (SCC), 11 carcinoma-in situ or dysplasia, and 22 morphologically normal oral biopsies, were analyzed for loss of heterozygosity (LOH) at 9p21, 3p21, and 17p13(TP53) by microsatellite analysis. LOH at one or more tested markers in at least one biopsy was detected in 76% (35 of 46) cases. All of the SCC and carcinoma-in situ cases showed LOH, and, strikingly, more than one-half (69%, 13 of 22) of morphologically normal epithelia also harbored LOH in at least one tested marker. The most frequent LOH was found on chromosome 9p21 (69%, 31 of 45). LOH was observed at 3p21, 17p13(TP53), or in multiple chromosomal arms significantly more often in SCC than in normal epithelia. In the majority of cases, two oral biopsies, one from an OraTest-staining positive area and another from a negative area adjacent to the stain, were collected. Among 25 LOH positive cases with two biopsies, identical allelic losses were confirmed between stained and nonstained biopsies in 16 cases. In the remaining nine cases with discordant LOH patterns between two biopsies, eight cases showed LOH at more genetic loci in OraTest-stained areas. Our data confirm that clonal genetic alterations, especially 9p21 deletion, are often present in the oral epithelia of patients with previous UADT malignancy and, combined with previous studies, suggest that genetic analysis will help stratify patients at risk of developing a secondary oral cancer. In addition to detecting cancer, our study suggests that OraTest can detect clinically occult lesions in the progression pathway to oral cancer.

Detection of head and neck squamous cell carcinoma among exfoliated oral mucosal cells by microsatellite analysis.

Prompt detection of head and neck squamous cell carcinoma (HNSCC) is vital to successful patient management. In this feasibility study, we used microsatellite analysis to detect tumor-specific genetic alterations in exfoliated oral mucosal cell samples from patients with known cancer. Exfoliated mucosal cells in pretreatment oral rinse and swab samples were collected from 44 HNSCC patients and from 43 healthy control subjects (20 nonsmokers and 23 smokers). We tested a panel of 23 informative microsatellite markers to assay DNA from the matched lymphocyte, tumor (from cancer cases), and oral test samples. Loss of heterozygosity or microsatellite instability of at least one marker was detected in 38 (86%) of 44 primary tumors. Identical alterations were found in the saliva samples in 35 of these 38 cases (92% of those with markers; 79% overall) including 12 of 13 cases with small primaries [stage Tt or Tx (occult primary)] and 4 of 4 cases of patients that had undergone prior radiation. Microsatellite instability was detectable in the saliva in 24 (96%) of 25 cases in which it was present in the tumor, and loss of heterozygosity was identified in the test sample in 19 (61%) of 31 cases. No microsatellite alterations were detected in any of the samples from the healthy control subjects. This approach must now be refined and validated for the detection of clinically occult disease. Microsatellite analysis of oral samples may then become a valuable method for detecting and monitoring HNSCC.

Oncologic rationale for bilateral tonsillectomy in head and neck squamous cell carcinoma of unknown primary source.

OBJECTIVE: To demonstrate an oncologic basis for the recommendation to perform bilateral tonsillectomy as a routine measure in the search for a primary mucosal lesion in patients presenting with cervical nodal metastasis of squamous cell carcinoma (SCC). STUDY DESIGN: A case series of individuals selected from a 3-year period is reported. SETTING: Academic medical center. RESULTS: Each individual presented with metastatic squamous cell carcinoma in a cervical lymph node from an unknown primary source. In each case, the primary source was identified in a tonsillectomy specimen, either located contralateral to the node, or in both tonsils. CONCLUSIONS: The rate of contralateral spread of metastatic cancer from occult tonsil lesions appears to approach 10%. For this reason, bilateral tonsillectomy is recommended as a routine step in the search for the occult primary in patients presenting with cervical metastasis of SCC and palatine tonsils intact.

The American Society of Anesthesiologists' class as a comorbidity index in a cohort of head and neck cancer surgical patients.

BACKGROUND: We assessed the American Society of Anesthesiologists' (ASA) class, as a measure of comorbidity in comparison to the commonly used Charlson index for prognostic ability in a HNCA population. METHODS: Proportional hazards methods were applied to head and neck cancer patients whose treatment included surgery by the Johns Hopkins Otolaryngology service (n = 388). RESULTS: The Charlson index and ASA class were modestly correlated (Spearman 0.36, p <.001). Compared with patients with ASA class 1 or 2, those with ASA class 3 or 4 had a two-fold elevated mortality rate (Relative Hazard (RH) = 2.00, 95% CI, 1.38-2.89). This association was stronger than observed for a Charlson index score of 1 or more compared with 0 (RH = 1.59, 95% CI, 1.17-2.17). Both the Charlson index and ASA class adjusted RHs displayed dose-response patterns (p value for trend <.001). CONCLUSIONS: Compared with the Charlson index, the ASA class had comparable if not greater prognostic ability for mortality in this elderly HNCA population.

Detection and quantitation of human papillomavirus (HPV) DNA in the sera of patients with HPV-associated head and neck squamous cell carcinoma.

The human papillomavirus (HPV) has been implicated as an etiological factor in a subset of head and neck squamous cell carcinoma (HNSCC). Because circulating tumor DNA has previously been detected in the sera of patients with advanced HNSCC (stage III or IV), we hypothesized that HPV DNA might be present in the sera of HPV-positive HNSCC patients. Serum DNA extracts from 70 patients with HNSCC were screened for HPV using conventional PCR and a real-time quantitative assay. All samples subjected to conventional PCR were further tested by dot blot hybridization, and positives were confirmed by Southern blotting. Paired tumor DNA from archived tissues was then similarly screened for HPV genomic material (n = 51) or tested by in situ hybridization (n = 19). HPV-16 DNA was detected with L1 primers in 0 of 65 sera and in 15 of 70 (21%) tumors. Conventional PCR with E7 primers and Southern blot hybridization detected HPV-16 DNA in four (6%) sera. Using real-time quantitative PCR, six samples were found to contain various levels of circulating HPV DNA (mean, 12 copies/ml; range, <1-35.) All six serum-positive patients had corresponding tumors positive for E7. Four of these patients with HPV-positive tumors later developed distant metastases, suggesting that HPV DNA in serum may represent occult hematogenous spread of cancer cells in this subset of patients. Although a much larger prospective trial is required, the presence of HPV genomic material in serum DNA of HPV-positive HNSCC patients may serve as a useful marker of early metastatic disease.

Two distinct regions of loss on chromosome arm 4q in primary head and neck squamous cell carcinoma.

OBJECTIVE: To more clearly define the frequency and the regions of chromosome arm 4q loss in head and neck squamous cell carcinoma. DESIGN: A retrospective microsatellite analysis of DNA from previously microdissected primary tumor samples. SETTING: Academic medical center. PATIENTS AND METHODS: One hundred primary tumor samples from patients with head and neck squamous cell carcinoma were analyzed for loss of heterozygosity on the long arm of chromosome 4. The Kaplan-Meier method was used to estimate survival for 97 patients for whom clinical data were available. The Cox proportional hazards model was used to compare survival, and logistic regression was used to search for associations between clinical tumor characteristics and 4q status. RESULTS: Analysis of 33 polymorphic microsatellite markers identified 51 samples (51%) exhibiting loss of heterozygosity of 4q in at least 1 locus. Eighteen tumors revealed loss at all informative markers, indicating monosomy or complete deletion of 4q. Thirty-three tumors displayed partial loss of heterozygosity and delineated 2 minimal areas of loss at 4q2324 and 4q2829. Eleven tumors displayed loss solely at the 4q2324 region, 13 tumors displayed deletions confined to the 4q2829 region, and 9 tumors displayed selective loss at both regions. A separate analysis in a subset of 94 primary head and neck tumors was done to further delineate the minimal area of chromosomal loss at 4q2324. Analysis of 8 markers in this region allowed us to identify the smallest region of loss between markers D4S2986 and D4S1564 (a distance of 2 centimorgans). Review of the clinical records of 97 patients revealed no statistically significant association between 4q status and any clinical variable, including survival. CONCLUSION: These results confirm a high frequency of chromosome arm 4q loss in primary head and neck squamous cell carcinoma and might demarcate 2 novel putative suppressor loci involved in progression of this carcinoma.

Head and neck surgery in the era of organ preservation therapy.

The role of surgery in the treatment of head and neck cancer has evolved over the past few decades. Surgery continues to be the primary treatment modality for early disease and for lesions in which extirpation provides a high rate of disease control without substantial loss of function (eg, oral cavity). Despite nonsurgical approaches aimed at organ preservation (ie, combined chemotherapy and radiation therapy), surgery continues to have a role in chemoradiation treatment strategies as salvage therapy and as a part of a treatment modality designed to preserve vital organ function. Salvage surgery is generally used after disease failure following a nonsurgical treatment approach and includes primary persistent disease and neck recurrence. Several function-sparing surgical options are available for the larynx, oral cavity, hypopharynx, and tongue base, including laser excision, supraglottic and vertical hemilaryngectomy, Pearson near-total laryngectomy, and various reconstruction methods. Function-sparing surgery combined with chemotherapy is currently under investigation and may provide optimal survival and function in selected patients with head and neck cancer.

Evidence for a causal association between human papillomavirus and a subset of head and neck cancers.

BACKGROUND: High-risk human papillomaviruses (HPVs) are etiologic agents for anogenital tract cancers and have been detected in head and neck squamous cell carcinomas (HNSCCs). We investigated, retrospectively, an etiologic role for HPVs in a large series of patients with HNSCC. METHODS: Tumor tissues from 253 patients with newly diagnosed or recurrent HNSCC were tested for the presence of HPV genome by use of polymerase chain reaction (PCR)-based assays, Southern blot hybridization, and in situ hybridization. The viral E6 coding region was sequenced to confirm the presence of tumor-specific viral isolates. Exons 5-9 of the TP53 gene were sequenced from 166 specimens. The hazard of death from HNSCC in patients with and without HPV-positive tumors was determined by proportional hazards regression analysis. RESULTS: HPV was detected in 62 (25%) of 253 cases (95% confidence interval [CI] = 19%-30%). High-risk, tumorigenic type HPV16 was identified in 90% of the HPV-positive tumors. HPV16 was localized specifically by in situ hybridization within the nuclei of cancer cells in preinvasive, invasive, and lymph node disease. Southern blot hybridization patterns were consistent with viral integration. Poor tumor grade (odds ratio [OR] = 2.4; 95% CI = 1.2- 4.9) and oropharyngeal site (OR = 6.2; 95% CI = 3.1-12.1) independently increased the probability of HPV presence. As compared with HPV-negative oropharyngeal cancers, HPV-positive oropharyngeal cancers were less likely to occur among moderate to heavy drinkers (OR = 0.17; 95% CI = 0.05-0.61) and smokers (OR = 0.16; 95% CI = 0.02-1.4), had a characteristic basaloid morphology (OR = 18.7; 95% CI = 2.1-167), were less likely to have TP53 mutations (OR = 0.06; 95% CI = 0.01-0. 36), and had improved disease-specific survival (hazard ratio [HR] = 0.26; 95% CI = 0.07-0.98). After adjustment for the presence of lymph node disease (HR = 2.3; 95% CI = 1.4- 3.8), heavy alcohol consumption (HR = 2.6; 95% CI = 1.4-4.7), and age greater than 60 years old (HR = 1.4; 95% CI = 0.8-2.3), all patients with HPV-positive tumors had a 59% reduction in risk of death from cancer when compared with HPV-negative HNSCC patients (HR = 0.41; 95% CI = 0.20-0.88). CONCLUSIONS: These data extend recent molecular and epidemiologic studies and strongly suggest that HPV-positive oropharyngeal cancers comprise a distinct molecular, clinical, and pathologic disease entity that is likely causally associated with HPV infection and that has a markedly improved prognosis.

Frequent gain of the p40/p51/p63 gene locus in primary head and neck squamous cell carcinoma.

We have identified a new human p53 homologue, p40 (p51/p63). This gene was mapped to the distal arm of 3q and was found to be essential for normal epithelial development. We used microsatellite and FISH analyses to search for genetic alterations of p40 in primary HNSCC. A more precise localization of p40 was completed using 6 known markers on 3q and a newly isolated microsatellite marker within the p40 gene. We also determined the genomic organization of the p40 gene using human YAC and BAC clones. Microsatellite analysis revealed that 14 of 26 (54%) primary HNSCC had allelic imbalance in at least 1 of the 7 microsatellite loci. However, FISH analysis with a p40 probe showed that a majority of HNSCC had an increased copy number of the locus regardless of allelic status. Thus, overrepresentation of the p40 locus may play an important role in the development of HNSCC.

Gene promoter hypermethylation in tumors and serum of head and neck cancer patients.

Promoter hypermethylation is an important pathway for repression of gene transcription in cancer cells. We analyzed aberrant DNA methylation at four genes in primary tumors from 95 head and neck cancer patients and then used the presence of this methylation as a marker for cancer cell detection in serum DNA. These four genes were tested by methylation-specific PCR and included: p16 (CDKN2A), O6-methylguanine-DNA-methyltransferase, glutathione S-transferase P1, and death-associated protein kinase (DAP-kinase). Fifty-five % (52 of 95) of the primary tumors displayed promoter hypermethylation in at least one of the genes studied: 27% (26/95) at p16, 33% (31 of 95) at O6-methylguanine-DNA-methyltransferase; and 18% (17 of 92) at DAP-kinase. No promoter hypermethylation was observed at the glutathione S-transferase P1 gene promoter. We detected a statistically significant correlation between the presence of DAP-kinase gene promoter hypermethylation and lymph node involvement (P = 0.014) and advanced disease stage (P = 0.016). In 50 patients with paired serum available for epigenetic analysis, the same methylation pattern was detected in the corresponding serum DNA of 21 (42%) cases. Among the patients with methylated serum DNA, 5 developed distant metastasis compared with the occurrence of metastasis in only 1 patient negative for serum promoter hypermethylation (P = 0.056). Promoter hypermethylation of key genes in critical pathways is common in head and neck cancer and represents a promising serum marker for monitoring affected patients.

Genetic progression and clonal relationship of recurrent premalignant head and neck lesions.

We constructed a preliminary genetic progression model for head and neck squamous cell carcinoma (HNSC) based on the frequency of genetic alterations in preneoplastic and neoplastic lesions from single biopsy specimens. To firmly establish the temporal order of established genetic events in HNSC, we sampled serial biopsies from five patients with recurrent premalignant lesions at a single anatomic site over a period of time (1 month to 144 months). These lesions were examined by microsatellite analysis of the minimal regions of loss on the 10 most frequently lost chromosomal arms in HNSC. Each set of serial biopsies from all five patients demonstrated LOH (loss of heterozygosity) of identical alleles at multiple loci with identical boundaries between areas of LOH and retention of heterozygosity, indicating a common clonal origin for each set. Three patients demonstrated genetic progression (new regions of LOH) over time correlating with histopathological progression, one patient demonstrated lack of genetic progression associated with unchanged histopathological morphology, and one patient demonstrated histopathological progression without detection of a corresponding genetic progression event. For one of these patients with a laryngeal tumor, at least four separate steps in progression to malignancy could be determined, accompanied by spatial expansion of an increasingly altered clonal population from the ipsilateral to the contralateral side, ultimately resulting in a malignancy. Microsatellite-based genetic analysis of recurrent premalignant lesions indicates that these lesions arise from a common clonal progenitor, followed by outgrowth of clonal populations associated with progressive genetic alterations and phenotypic progression to malignancy.

Head and neck cancer in nonsmokers: a distinct clinical and molecular entity.

OBJECTIVES/HYPOTHESIS: Clinical and molecular patterns of head and neck squamous cell carcinoma (HNSCC) in nonsmokers and smokers may be different. Analysis of these patterns may improve understanding and management of this disease. STUDY DESIGN: three hundred five subjects were included (46 nonsmokers, 29 former smokers, and 230 smokers). Subsets were analyzed for p53 mutation, human papillomavirus (HPV), and loss of heterozygosity (LOH) at 10 chromosomal loci. METHODS: Clinical information was analyzed for common patterns of disease among the groups. The p53 gene was sequenced, and polymerase chain reaction was used to detect HPV DNA and LOH at two microsatellite markers for each loci. The chi2 test was used to assess differences in genetic alterations between groups, logistic regression to examine the independence of association of tobacco exposure with each alteration, and Kaplan Meier estimates and the log-rank statistic to assess differences in survival. RESULTS: Nonsmokers included a disproportionate number of women, oral cavity (especially tongue) tumors, and very young or old individuals. Smokers had more tumors of the larynx, hypopharynx, and floor of mouth. The rate of p53 mutation was much greater in smokers; the percentage with HPV was marginally lower. The percentage of LOH at 3p, 4q, and 11q13, and the overall average number of chromosomal losses, was significantly lower in nonsmokers' tumors. Survival did not vary with smoking or age. CONCLUSIONS: The clinical and genetic features of HNSCC are distinct between groups defined by tobacco use. Tumors of nonsmokers contain a lower frequency of common genetic alterations, suggesting that the underlying changes in these tumors may remain undiscovered.

Immunohistochemical detection of p53 protein accumulation in head and neck cancer: correlation with p53 gene alterations.

The genetic and functional status of the p53 gene may be an important factor in guiding therapeutic strategies for patients with cancer. The purpose of this study was to determine whether p53 immunohistochemistry (IHC) accurately reflects the mutational status of the p53 gene and to determine whether p53 IHC independently predicts tumor responsiveness to radiation therapy for patients with HNSCC. p53 IHC was performed using the monoclonal antibody DO7 on tumors from 85 patients with HNSCC treated with primary or adjuvant radiation. The p53 status in all of these tumors was previously assessed by direct sequence analysis of exons 5 through 9: 49 tumors were p53 wild-type, and 36 harbored p53 gene mutations. All patients were well characterized with respect to locoregional recurrence, distant spread, and survival. Positive p53 staining was observed in 53 of the 85 cases (62%). Only 27 (51%) of these 53 IHC-positive cases harbored gene mutations in exons 5 through 9; 23 (72%) of the 32 IHC-negative cases did not harbor mutations. The overall correlation rate between IHC and sequencing was 59% (P < .04, chi2). Discordant results were observed for 35 (41%) cases, including 26 IHC-positive cases and 9 IHC-negative cases. In 7 of 9 cases, false-negative staining was due to a nonsense or splice-site mutation. p53 IHC was not predictive of overall survival (P = .37) or disease-free survival (P = .95). In a sizable number of cases, p53 IHC does not reflect the mutational status of the p53 gene. Specific types of alterations (eg, truncating mutations) and other factors may contribute to this poor correlation. Moreover, p53 IHC does not appear to be an independent predictor of tumor responsiveness to radiation in patients with HNSCC.

Second esophageal tumors in patients with head and neck squamous cell carcinoma: an assessment of clonal relationships.

Patients with squamous cell carcinoma of the head and neck (HNSCC) often develop second carcinomas elsewhere in the upper aerodigestive tract. Some of these paired tumors share a common origin, reflecting the ability of a single progenitor cell to replicate, expand, and populate contiguous regions of the upper aerodigestive tract-a process referred to as clonal expansion. The geographical limitations of clonal expansion, however, have not been adequately addressed. For example, it is not known whether a neoplastic clone from the oral cavity, pharynx, or larynx can migrate to the esophagus. We compared paired tumors from 16 patients with HNSCC and a second squamous cell carcinoma of the esophagus (ESCC) for patterns of allelic loss on chromosomal arms 3p, 9p, and 17p. Losses at these loci occur early during neoplastic transformation of the respiratory tract. In 14 cases (87%), the paired tumors had discordant patterns of allelic loss, suggesting that these tumors were not clonally related. Conversely, two (13%) of the 16 paired tumors had identical genetic alterations, which suggests clonal expansion as the mechanism underlying tumor multifocality. One clone spread from the hypopharynx into the cervical esophagus, and the other spread from the tonsil to the distal esophagus. Although most second ESCCs appear to arise as independent neoplasms, a clonal population of neoplastic cells is capable of traveling across substantial distances to give rise to second tumors at different anatomical sites.

Cyclin D1 amplification is independent of p16 inactivation in head and neck squamous cell carcinoma.

Progression through the G1 phase of the cell cycle is mediated by phosphorylation of the retinoblastoma protein (pRb) resulting in the release of essential transcription factors such as E2F-1. The phosphorylation of pRb is regulated positively by cyclin D1/CDK4 and negatively by CDK inhibitors, such as p16 (CDKN2/MTS-1/INK4A). The p16/cyclin D1/Rb pathway plays a critical role in tumorigenesis and many tumor types display a high frequency of inactivation of at least one component of this pathway. In order to determine the overall contribution of these three components to progression of head and neck squamous cell carcinoma (HNSCC), we examined p16 inactivation, cyclin D1 amplification, and pRb expression in 23 primary HNSCC tumors and five cell lines. p16 inactivation was detected in 19/23 (83%) primary tumors by detailed genetic analysis and was confirmed by immunohistochemistry (IHC). Absence of Rb protein expression indicative of pRb inactivation was identified in 2/23 (9%) tumors. In this set of tumors, there was a perfect inverse correlation between p16 and pRb inactivation. Using fluorescence in situ hybridization (FISH) cyclin D1 amplification was identified in 4/5 (80%) cell lines and 4/11 (36%) primary tumors. However, 2/4 cell lines and all four primary tumors with cyclin D1 amplification contained a concomitant alteration of p16. Therefore 21/ 23 (91%) of primary HNSCC contained at least one alteration in the p16/cyclin D1/Rb pathway. Although p16 and Rb alteration are apparently exclusive, cyclin D1 amplification occurs concomitantly with the loss of p16 suggesting an additional role for this amplification in HNSCC.

Human papillomavirus in head and neck squamous cell carcinoma: are some head and neck cancers a sexually transmitted disease?

There is abundant epidemiologic and virologic evidence that high-risk human papillomaviruses (HPVs) are tumorigenic in human epithelia, particularly in the cervix, where HPV infection is necessary for cancer development. HPV DNA has been detected in a proportion of head and neck squamous cell carcinomas (HNSCCs) in numerous case series. The mere presence of the virus in tumor specimens, by itself, does not imply a causal relationship. However, recent studies support an etiologic role for HPVs in a subset of HNSCC, particularly poorly differentiated tumors arising from Waldeyer's tonsillar ring. Epidemiologic studies have shown that exposure to HPV increases the risk of HNSCC, and HPV infection may interact with alcohol and tobacco exposure in tumor promotion. Molecular studies indicate that transcriptionally active virus is confined to tumor cells. It will be important to clarify further the role that HPV has in HNSCC development, because HPV-based therapeutic vaccines which are currently being developed for cervical cancer may also be of benefit in the management of HNSCC.