Mutagen sensitivity in patients with head and neck cancers: a biologic marker for risk of multiple primary malignancies.

Eighty-four patients with head and neck cancers were evaluated for in vitro sensitivity to mutagens and then followed longitudinally for development of multiple primary malignancies. We assessed mutagen sensitivity by exposing lymphocytes to bleomycin in vitro and quantitating the bleomycin-induced chromosomal breaks per cell. The mutagen-hypersensitive patients, ie, those who expressed greater than 1.0 break per cell, were significantly more likely to develop multiple primary cancers than were patients who were less sensitive (less than or equal to 1.0 break per cell) (relative risk = 4.4; 95% confidence limits = 1.2, 15.8). This relationship was independent of age, sex, site, and treatment of first primary cancer and tobacco or alcohol exposures. Sensitivity to bleomycin-induced chromosomal damage serves as an indicator of genetic susceptibility to multiple primary malignancies in patients with head and neck cancers.     

Frequent 3p allele loss and epigenetic inactivation of the RASSF1A tumour suppressor gene from region 3p21.3 in head and neck squamous cell carcinoma

Studies of allelic imbalance and suppression of tumourigenicity have consistently suggested that the short arm of chromosome three (3p) harbours tumour suppressor genes (TSGs) whose inactivation leads to the development of various types of neoplasia including head and neck squamous cell carcinoma (HNSCC). Previously, we defined a critical minimal region of 120kb at 3p21.3 that contains overlapping homozygous deletions in lung and breast tumour lines and isolated eight genes from the minimal region. Mutation analysis in a large panel of lung and breast cancers revealed only rare mutations, but the majority of lung tumour lines showed loss of expression for one of the eight genes (RASSF1A) due to hypermethylation of a CpG island in the promoter region of RASSF1A. We found RASSF1A to be methylated in the majority of lung tumours, but to a lesser extent in breast and ovarian tumours. In order to define the role of 3p TSGs, in particular RASSF1A in HNSCC, we (a) analysed 43 primary HNSCC for allelic loss in regions proposed to contain 3p TSGs (3p25-26, 3p24, 3p21-22, 3p14 and 3p12), (b) analysed 24 HNSCC for evidence of RASSF1A methylation and (c) undertook mutation analysis of RASSF1A in HNSCC. We found that 81% of HNSCC showed allele loss at one or more 3p markers, 66% demonstrated loss for 3p21.3 markers and 56% showed allelic losses at 3p12 loci. Thus, 3p loss is common in HNSCC and extensive 3p loss occurs even in early stage tumours. RASSF1A promoter region hypermethylation was found in 17% (4/24) of the sporadic HNSCC, but RASSF1A mutations were not identified. Furthermore, we found RASSF1A methylation to be significantly higher in poorly differentiated then in moderate to well differentiated HNSCC (P=0.0048). Three of the four tumours showing RASSF1A methylation also underwent 3p21.3 allelic loss, hence RASSF1A behaves as a classical TSG (two hits, methylation and loss). One tumour with RASSF1A methylation had retention of markers at 3p providing further evidence of specific inactivation of RASSF1A as a critical step in some HNSCC. Although the frequency of 3p21.3 allele loss was substantially higher than that of RASSF1A methylation this does not necessarily suggest that other genes from 3p21.3 are also implicated in HNSCC, as 3p21.3 LOH was invariably found with LOH at other 3p loci. Thus, the presence of 3p21.3 allele loss without RASSF1A methylation might reflect a propensity for 3p21.3 loss to occur as a secondary consequence of large 3p deletions targeted at other 3p TSG regions. Furthermore, in the presence of homozygous inactivation of other 3p TSGs, RASSF1A haploinsufficiency might be sufficient to promote tumourigenesis in many HNSCC.     

Environmental tobacco smoking, mutagen sensitivity, and head and neck squamous cell carcinoma.

Although active tobacco smoking has been considered a major risk factor for head and neck cancer, few studies have evaluated environmental tobacco smoke (ETS) and its interaction with mutagen sensitivity on the risk of head and neck cancer. We investigated the relationship between ETS and head and neck cancer in a case-control study of 173 previously untreated cases with pathologically confirmed diagnoses of squamous cell carcinoma of the head and neck and 176 cancer-free controls at Memorial Sloan-Kettering Cancer Center between 1992 and 1994. A structured questionnaire was used to collect ETS exposure and other covariates including a history of active tobacco smoking and alcohol use. ETS measures include a history of ETS exposure at home and at workplace. The associations between passive smoking and head and neck cancer were analyzed by Mantel-Haenszel methods and logistic regression models. Additive and multiplicative models were used to evaluate effect modifications between ETS and mutagen sensitivity. The crude odds ratio (OR) for ETS exposure was 2.8 [95% confidence intervals (CI), 1.3-6.0]. Controlling for age, sex, race, education, alcohol consumption, pack-years of cigarette smoking, and marijuana use, the risk of squamous cell carcinoma of the head and neck was increased with ETS (adjusted OR, 2.4; 95% CI, 0.9-6.8). Dose-response relationships were observed for the degree of ETS exposure; the adjusted ORs were 2.1 (95% CI, 0.7-6.1) for those with moderate exposure and 3.6 (95% CI, 1.1-11.5) for individuals with heavy exposure (P for trend = 0.025), in comparison with those who never had ETS exposures. These associations and the dose-response relationships were still present when the analysis was restricted to nonactive smoking cases and controls (crude OR, 2.2; 95% CI, 0.6-8.4). Crude odds ratios were 1.8 for those with moderate ETS exposure and 4.3 for individuals with heavy ETS exposure among nonsmoking cases and controls (P for trend = 0.008). More than multiplicative interaction was suggested between passive smoking and mutagen sensitivity. This study suggests that ETS exposure may increase the risk of head and neck cancer with a dose-response pattern. Our analysis indicated that passive smoking may interact with mutagen sensitivity and other risk factors to increase the risk of head and neck cancer. Our results need to be interpreted with caution because of potential residual confounding effects of active tobacco smoking and other methodological limitations. Future large-scale studies are warranted to confirm our findings.     

Correlation of allelic losses and clinicopathological factors in 504 primary breast cancers

BACKGROUND: We have defined 18 chromosomal regions in which allelic losses were frequent among breast cancers. We examined whether specific allelic losses might correlate with any clinicopathological factors. METHODS: We tested DNA from matched normal and tumor tissues for loss of heterozygosity (LOH) at 18 microsatellite loci from a cohort of 504 patients who had undergone surgery for breast cancer. RESULTS: LOH at 3p14.3 correlated with a larger size of tumor (greater than 2 cm). LOH at 1p22, 3p25.1, 3p14.3, or 17q21.1 correlated with loss of estrogen receptors. LOH at as many as eleven regions correlated with loss of progesterone receptor, suggesting that these represent general phenomena associated with progression of cancer. Above all, allelic losses at 11q23-24, 13q12, 17p13.3, or 22q13 significantly correlated with lymph-node metastasis (11q23-24, p= 0.0042; 13q12, p=0.0207; 17p13.3, p=0.0478; 22q13, p=0.0162). CONCLUSION: These results suggest that some clinical characteristics of breast cancers are determined by loss of tumor suppressor genes present at specific chromosome regions. Especially, LOH at 11q23-24, 13q12, 17p13.3, and 22q13 is a significant predictor of lymph-node metastasis for patients who have undergone surgery for breast cancer, and may serve as a negative prognostic indicator.     

Smoking and drinking can induce p15 methylation in the upper aerodigestive tract of healthy individuals and patients with head and neck squamous cell carcinoma

BACKGROUND: The consumption of tobacco and alcohol has been implicated in the development of head and neck squamous cell carcinoma (HNSCC). Promoter methylation of tumor suppressor genes is common in HNSCC. In this study, the authors evaluated the effects of tobacco and alcohol on p15 gene methylation of cells in cells from the mouth and throat of physically healthy individuals and patients with HNSCC. METHODS: The study participants were divided into 3 groups, including a group of 37 healthy nonsmokers and nondrinkers, a group of 22 healthy smokers and/or drinkers and a group of 31 patients with HNSCC. RESULTS: Methylation of p15 was detected in cells obtained from mouth and throat (M&T) rinsing fluid samples from 3 of 37 healthy individuals (8%) who did not drink or smoke, from 15 of 22 healthy smokers and/or drinkers (68%), and from 15 of 31 patients (48%) with HNSCC. Among 31 patients with HNSCC, 20 patients (65%) had methylated p15 gene in their tumor biopsies. With the use of beta-actin as a reference, the ratio of methylated p15 to beta-actin was calculated as an index of the percentage of cells with p15 methylation. The percentage of exfoliated cells from M&T rinsing fluid samples that had p15 methylation ranged from 0% to 11% for patients with HNSCC and from 0% to 21% for healthy smokers/drinkers, respectively. The methylation index of tumor cells with p15 methylation ranged from 0% to 65%. CONCLUSIONS: The results suggest that p15 gene methylation can be induced by chronic smoking and drinking and may play a role in the very early stages of carcinogenesis in HNSCC.     

p53 alterations predict tumor response to neoadjuvant chemotherapy in head and neck squamous cell carcinoma: a prospective series.

PURPOSE: The tumor suppressor gene p53 plays a crucial role in cell cycle control and apoptosis in response to DNA damages. p53 gene mutations and allelic losses at 17p are one of the most common genetic alterations in primary head and neck squamous cell carcinoma (HNSCC). Alterations of the p53 gene have been shown to contribute to carcinogenesis and drug resistance. PATIENTS AND METHODS: In this prospective series, patients with HNSCC were treated with cisplatin-fluorouracil neoadjuvant chemotherapy. p53 status was characterized in 106 patients with HNSCC (p53 mutations, allelic losses at p53 locus, and plasma anti-p53 antibodies) to determine the existence of a relationship between p53 gene status and response to neoadjuvant chemotherapy. RESULTS: Exons 4 to 9 of the p53 gene were analyzed, and mutations were found in 72 of 106 patients with HNSCC. p53 mutations were associated with loss of heterozygosity at chromosome 17p (P <.001). The prevalence of p53-mutated tumors was higher in the group of patients with nonresponse to neoadjuvant chemotherapy than in the group of responders (81% v 61%, respectively; P <.04). When compiling p53 mutations and anti-p53 antibodies in plasma, the correlation between p53 status and response to chemotherapy was significant (87% v 57%, respectively; P =.003). A multivariate analysis showed that p53 status is an independent predictive factor of response to chemotherapy. CONCLUSION: This prospective study suggests that p53 status may be a useful indicator of response to neoadjuvant chemotherapy in HNSCC.     

Synchronous cancers in patients with head and neck cancer

BACKGROUND:

Second primary malignancies (SPMs) are the leading cause of death in survivors of head and neck squamous cell carcinoma (HNSCC). Synchronous SPMs are of significant clinical interest because they potentially can be identified by screening procedures at the time of diagnosis of the index cancer. Recently, human papillomavirus (HPV) has emerged as a distinct risk factor for oropharyngeal head and neck squamous cell carcinoma (HNSCC), differing from classic tobacco/alcohol‐associated HNSCC, suggesting that there also may be distinct patterns of synchronous SPMs.

METHODS:

The authors performed a population‐based cohort study in 64,673 patients in the National Cancer Institute Surveillance, Epidemiology, and End Results registry (1979‐2008), defining risks of synchronous SPM in patients with HNSCC who were diagnosed before and after the emergence of prevalent HPV‐associated oropharyngeal HNSCC. Excess risk was calculated using standardized incidence ratios (SIR) and excess absolute risk per 100 patients.

RESULTS:

Among patients with HNSCC, the SIR of synchronous SPM was 5.0, corresponding to 2.62 excess cases per 100 patients. The site with the highest excess risk of a second cancer was the head and neck (SIR, 41.4), followed by the esophagus (SIR, 21.8), and lung (SIR, 7.4). The risk of synchronous SPM changed markedly over time for patients with oropharyngeal HNSCC. In the 1970s and 1980s, oropharyngeal cancers carried the highest risk of SPM. Risk began to dramatically decline in the 1990s; and currently, oropharyngeal cancers carry the lowest risk of synchronous SPM.

CONCLUSIONS:

The current data are consistent with the etiologic shift of oropharyngeal HNSCC, from a primarily tobacco‐associated malignancy associated with significant field cancerization of the upper aerodigestive mucosa, to a malignancy primarily caused by oncogenic human papillomavirus. Cancer 2013. © 2013 American Cancer Society.     

Genome-wide DNA copy number alterations in head and neck squamous cell carcinomas with or without oncogene-expressing human papillomavirus

Oncogene-expressing human papillomavirus type 16 (HPV16) is found in a subset of head and neck squamous cell carcinomas (HNSCC). HPV16 drives carcinogenesis by inactivating p53 and pRb with the viral oncoproteins E6 and E7, paralleled by a low level of mutations in TP53 and allelic loss at 3p, 9p, and 17p, genetic changes frequently found in HNSCCs of nonviral etiology. We hypothesize that two pathways to HNSCC exist: one determined by HPV16 and the other by environmental carcinogens. To define the critical genetic events in these two pathways, we now present a detailed genome analysis of HNSCC with and without HPV16 involvement by employing high-resolution microarray comparative genomic hybridization. Four regions showed alterations in HPV-negative tumors that were absent in HPV-positive tumors: losses at 3p11.2-26.3, 5q11.2-35.2, and 9p21.1-24, and gains/amplifications at 11q12.1-13.4. Also, HPV16-negative tumors demonstrated loss at 18q12.1-23, in contrast to gain in HPV16-positive tumors. Seven regions were altered at high frequency (>33%) in both groups: gains at 3q22.2-qter, 5p15.2-pter, 8p11.2-qter, 9q22-34.1, and 20p-20q, and losses at 11q14.1-qter and 13q11-33. These data show that HNSCC arising by environmental carcinogens are characterized by genetic alterations that differ from those observed in HPV16-induced HNSCC, and most likely occur early in carcinogenesis. A number of genetic changes are shared in both tumor groups and can be considered crucial in the later stages of HNSCC progression.     

LOH-profiling by SNP-mapping in a case of multifocal head and neck cancer

AIM: To introduce an approach for the detection of putative genetic host factors that predispose patients to develop head and neck squamous cell carcinomas (HNSCC).METHODS: HNSCC most often result from the accumulation of somatic gene alterations found in tumor cells. A cancer-predisposing genetic background must be expected in individuals who develop multiple cancers, starting at an unexpectedly young age or with little carcinogen exposure. Genome-wide loss of heterozygosity (LOH) profiling by single nucleotide polymorphism microarray mapping was performed in a patient with a remarkable history of multifocal HNSCC.RESULTS: Regions of genomic deletions in germline DNA were identified on several chromosomes with a remarkable size between 1.6 Mb and 8.1 Mb (mega base-pair). No LOH was detected at the genomic location of the tumor suppressor gene P53.CONCLUSION: Specific patterns of germline DNA deletions may be responsible for susceptibility to HNSCC and should be further analyzed.     

Increased mutagen sensitivity in head-and-neck squamous-cell carcinoma patients,particularly those with multiple primary tumors

Mutagen sensitivity is a constitutional factor which may be used to identify head-and-neck squamous-cell carcinoma (HNSCC) patients at high risk for the development of multiple primary tumors (MPT). In this retrospective study, mutagen sensitivity was measured in HNSCC patients with a single primary tumor (SPT), HNSCC patients who have already developed MPT and control subjects with no tumor history. In vitro, lymphocytes were challenged with bleomycin and chromosomal damage was quantified by scoring chromatid breaks of 100 cells. A significant difference in the mean number of breaks per cell (b/c) was found between SPT patients and controls. Patients with MPT showed a significantly higher mean b/c value than SPT patients. This increase in mutagen sensitivity in HNSCC patients was not related to well-known cancer risk factors such as age, or life-style factors such as smoking and alcohol drinking habits. In addition, tumor site but not tumor stage was found to be related to mutagen sensitivity. On the basis of our findings, we propose that mutagen sensitivity is not an independent risk factor but a constitutional factor which reflects the way in which genotoxic compounds are dealt with and is thereby directly related to cancer risk.     

Influence of the persistence of tobacco and alcohol use in the appearance of second neoplasm in patients with a head and neck cancer. A case–control study

Objective  To evaluate the influence of persistent tobacco and alcohol use on the risk of a second metachronous neoplasm in the aerodigestive tract in head and neck squamous cell carcinoma (HNSCC) patients. Methods  A matched case–control study was carried out in 514 patients with HNSCC. Case patients developed a second metachronous neoplasm in the aerodigestive tract after treatment of an index HNSCC. A patient free of second neoplasm was individually matched to every case patient by location of the index tumor, tumor stage, sex, previous tobacco and alcohol consumption, age, general health status, and treatment. Data about persistence in tobacco and alcohol consumption after treatment of the index tumor was collected retrospectively. A validation study was carried out to confirm the adequacy of this retrospective information. Results  Persistent tobacco smoking and alcohol drinking after treatment of a HNSCC contributed to the risk of appearance of second neoplasm. The odds ratio of a second neoplasm for patients who continued to smoke was 2.9 (95% CI OR 1.8–4.1), and for patients who continued to use alcohol it was 5.2 (95% CI OR 3.3–7.9). There was a strong association between persistence of tobacco and alcohol use after treatment of the HNSCC index tumor. According to the attributable risk estimation, persistent tobacco and alcohol consumption would be responsible for one-third of the second neoplasms in the patients with a HNSCC index tumor. Conclusions  Persistence of tobacco and alcohol use after treatment of a HNSCC had a significant influence on the appearance of a second neoplasm in the aerodigestive tract. Cessation of tobacco and alcohol use should be a major goal after treatment of a HNSCC.     

Genetic alterations in head and neck cancer: interactions among environmental carcinogens, cell cycle control, and host DNA repair

Head and neck squamous cell carcinomas (HNSCC) arise as a consequence of cumulative genetic changes brought about by continued exposure to carcinogens associated with tobacco and alcohol use, influenced by viral agents such as human papillomaviruses, in a background of acquired or heritable genetic susceptibility. The presence of widespread genomic instability in HNSCC, such as cytogenetic aberrations, allelic imbalance/loss of heterozygosity, and microsatellite instability, suggests that there is an imperfection in the host DNA repair machinery. Genomic instability with progressive accumulation of detrimental genetic alterations appears to be dependent upon a circuitous interaction between the environmental genotoxic insults and the host DNA repair machinery, the functional integrity of which is governed by the proper cell cycle control and host DNA repair capacity. Thus, it can be hypothesized that continued exposure to environmental carcinogens (ie, longstanding history of smoking and drinking), loss of proper cell cycle control (eg, inactivation of p53 or p16 tumor suppressor genes or amplification of the proto-oncongene cyclin D1), and impaired DNA repair capacity (both inherited and acquired) are prerequisites in head and neck carcinogenesis.     

Tobacco-specific carcinogen nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone induces AKT activation in head and neck epithelia

Exposure to tobacco carcinogens is causally associated with head and neck squamous cell carcinoma (HNSCC), but the underlying molecular mechanisms remain unclear. Here, we reported that AKT is activated at a higher frequency in both HNSCC tumors and the adjacent mucosa from HNSCC patients who are smokers than those from HNSCC patients who are non-smokers. Adding physiologically relevant concentrations of 4-(methylnitrosamino)-1-(3-pyridyl)-1-1butanone (NNK), a major tobacco carcinogen, to normal head and neck epithelial cells and HNSCC cell lines, rapidly and constitutively activated AKT through phosphorylation in a dose- and time-dependent manner. AKT phosphorylation was associated with activation of downstream signaling mediators BAD, MDM2, GSK-3β, mTOR. These alterations correlated with increased proliferation and decreased etoposide-induced apoptosis in NNK-exposed cells. Finally, NNK exposure to mouse head and neck epithelia resulted in epithelial hyperproliferation and reduced apoptosis, which is correlated with AKT activation. Our results suggest that AKT activation is an early event and plays a pivotal role in mediating tobacco-induced HNSCC carcinogenesis.     

Frequent genetic and biochemical alterations of the PI 3-K/AKT/PTEN pathway in head and neck squamous cell carcinoma

We investigated the status of the PI 3-kinase/AKT/PTEN signaling pathway in a series of 117 head and neck squamous cell carcinomas (HNSCC) in a search for molecular alterations in genes/proteins with potential prognostic value. For this purpose, PIK3CA and AKT2 gene amplification was assessed by multiplex and Quantitative Real-Time PCR. Protein expression of AKT, p-AKT, p110alpha and PTEN was determined by Western blot. PTEN allelic loss was evaluated by microsatellite analysis. PTEN-exon 5 was screened for point mutations by PCR-SSCP. Homozygous deletions were determined by multiplex PCR. PIK3CA gene was amplified in 43/117 (37%) fresh tumor samples, a frequency that did not differ from that found in archival premalignant tissues: 15/38 (39%); 12/40 (30%) fresh tumors harbored AKT2 gene amplification. AKT was found activated in 6/36 (17%) fresh tumor samples, when compared to their normal tissue counterparts. Of these 6 cases, 1 showed p110alpha overexpression and 5 displayed PTEN protein downregulation. Neither allelic loss (found in 11/77 informative cases) nor point mutations or homozygous deletions accounted for the reduced PTEN protein expression observed in our tumor series. The histologically normal mucosa of 4 patients displayed some of the molecular alterations analyzed. Dysregulation of the PI 3-K/AKT/PTEN pathway might contribute to early HNSCC tumorigenesis and might constitute a potential clinical target. Overall, 17/36 (47%) cases showed at least 1 of the molecular alterations studied here, which makes the PI 3-kinase-initiated signaling pathway one of the most frequently altered in HNSCC.     

Duration but not intensity of alcohol and tobacco exposure predicts p16INK4A homozygous deletion in head and neck squamous cell carcinoma

In tobacco-associated solid tumors, evidence suggests that the pattern of carcinogen exposure is related to the nature of somatic gene inactivation within crucial pathways, including the retinoblastoma (Rb) pathway. One somatic event in this pathway, homozygous deletion of the p16INK4A gene, is commonly observed in head and neck squamous cell carcinoma (HNSCC). Alcohol and tobacco are both well-established risk factors for HNSCC but there has been little characterization of the relationship of exposure to these carcinogens and inactivation of the p16INK4A gene. Hypothesizing that p16INK4A homozygous deletion is associated with tobacco and alcohol exposure, we investigated 330 consecutive HNSCC tumors. The odds ratio (OR) for p16INK4A homozygous deletion among alcohol consumers in the upper tertile (>43 years used) was 5.2 [95% confidence interval (95% CI), 2.1-12.8] as compared with those with < or = 43 years of alcohol consumption. Intensity of alcohol exposure, measured as average alcoholic drinks per week, was not associated with gene deletion. When we examined the distribution of duration of tobacco use, the OR for p16(INK4A) homozygous deletion was 1.3 (95% CI, 0.5-3.0) and 1.9 (95% CI, 0.9-4.0) for 29 to 39 years and >39 years of tobacco smoking, respectively, as compared with those that smoked < or = 28 years. As in the case of alcohol use, intensity of tobacco exposure (measured as packs per day) was not associated with gene deletion. Hence, the duration of alcohol use and duration of smoking, but not intensity of either, significantly predicted p16(INK4A) homozygous deletion in HNSCC.     

Pocket proteins suppress head and neck cancer

Head and neck squamous cell carcinomas (HNSCC) is a common cancer in humans long known to be caused by tobacco and alcohol use, but now an increasing percentage of HNSCC is recognized to be caused by the same human papillomaviruses (HPV) that cause cervical and other anogenital cancers. HPV-positive HNSCCs differ remarkably from HPV-negative HNSCCs in their clinical response and molecular properties. From studies in mice, we know that E7 is the dominant HPV oncoprotein in head and neck cancer. E7 is best known for its ability to inactivate pRb, the product of the retinoblastoma tumor susceptibility gene. However, loss of pRb function does not fully account for potency of E7 in causing head and neck cancer. In this study, we characterized the cancer susceptibility of mice deficient in the expression of pRb and either of two related "pocket" proteins, p107 and p130, that are also inactivated by E7. pRb/p107-deficient mice developed head and neck cancer as frequently as do HPV-16 E7 transgenic mice. The head and neck epithelia of the pRb/p107-deficient mice also displayed the same acute phenotypes and biomarker readouts as observed in the epithelia of E7 transgenic mice. Mice deficient for pRb and p130 in their head and neck epithelia showed intermediate acute and tumor phenotypes. We conclude that pRb and p107 act together to efficiently suppress head and neck cancer and are, therefore, highly relevant targets of HPV-16 E7 in its contribution to HPV-positive HNSCC.     

Allelic losses at chromosome 8p21-23 are early and frequent events in the pathogenesis of lung cancer

Allelic losses on the short arm of chromosome 8 (8p) have been reported as frequent events in several cancers, including lung. However, no comprehensive mapping analysis of chromosome 8p in lung cancer tumors has been performed, and no data are available about the stage at which these abnormalities occur during the multistage development of lung cancer. Using 26 microsatellite markers, we mapped the chromosome 8 regions frequently deleted in lung cancer in 13 small cell carcinoma and 17 non-small cell lung carcinoma cell lines and in 68 microdissected archival primary lung tumors (22 small cell lung carcinomas, 25 squamous cell carcinomas, and 21 adenocarcinomas). We also studied the role of 8p deletions in lung cancer pathogenesis by examining 95 microdissected normal epithelium and preneoplastic samples from 11 surgically resected squamous cell lung carcinomas and from 58 bronchoscopy biopsy samples obtained from 31 current and former smokers. High frequencies of deletions at 8p21-23 regions were detected in lung cancer cell lines and in primary lung tumors. Deletions commenced early during the multistage development of lung cancer at the hyperplasia/metaplasia stage in cancer patients and in smokers without cancer. Allelic deletions persisted for up to 48 years after smoking cessation. There was a progressive increase of the overall 8p21-23 loss of heterozygosity frequency and in the size of the deleted region with increasing severity of histopathological preneoplastic changes. In epithelial samples from resected squamous cell lung carcinomas, we compared the presence of loss of heterozygosity at 8p21-23 with deletions at chromosomes 3p and 9p. Of interest, the pattern of deletions was not random, and 8p21-23 allelic losses always followed 3p deletions and usually followed 9p deletions. We conclude that 8p21-23 deletions are frequent and early events in the pathogenesis of lung carcinomas.     

Head and neck cancer: changing epidemiology and public health implications

Characterizing the epidemiology of head and neck cancers is challenging and has received limited attention in the medical literature. Traditionally, 80%-90% of head and neck squamous cell carcinomas (HNSCCs) have been attributed to tobacco and alcohol use, but with growing public awareness and tobacco control efforts over the past few decades, there has been a downward trend in smoking prevalence in the US. There is also emerging evidence that human papillomavirus (HPV) is responsible for inconsistencies in HNSCC trends, with oncogenic HPV DNA found in approximately half of oropharyngeal cancers and in a high proportion of oropharyngeal cancers in nonsmokers and nondrinkers. The risk to HNSCC epidemiology is that whatever gains continue to be made in tobacco control may become lost in the increasing numbers of oropharyngeal cancers due to HPV. The purpose of this review is to explore the changing epidemiology of HNSCC, focusing on how it has been shaped by health policy and advocacy interventions and how it will continue to have public health implications in the future, particularly in considering preventive strategies against HPV. Given that the majority of HNSCCs are the result of exposure to preventable public health risks, more focus should be given to this area.     

Role of Tobacco in the Development of Head and Neck Squamous Cell Carcinoma in an Eastern Indian Population

Head and neck squamous cell carcinoma (HNSCC) accounts for about 30-40% of all cancer types in Indiaand the subcontinent in general. HNSCCs are primarily not hereditary, but rather a disease of older and middleaged adults. Many etiological factors like tobacco, alcohol and HPV infection are known to play importantroles. Eastern India, particularly Kolkata, has a population heavily exposed to various types of smoked andsmokeless tobacco, with only limited exposure to alcoholic beverages. Since there have been no previousepidemiological studies on tobacco as the main risk factor for head and neck carcinogenesis in Kolkata, we herecarried out a hospital based case control study in the city and its adjoin regions. Data from 110 patients diagnosedwith HNSCC and a similar number of matched control samples were analyzed using chi-square (χ2) test. Survivalstatus of the patients was also analyzed using the Kaplan-Meier method. A tobacco habit was significantlycorrelated with the incidence of HNSCC and persons with current addiction had a 2.17 fold increased risk ofcancer development. Dose-response relationships were seen for the frequency (p=0.01) and duration (p=0.02) oftobacco exposure with the risk. No significant difference in impact was found with smoked as opposed to smokelesstobacco in the development of the disease. Among HNSCC patients, significant poor survival in cases withtobacco habit than in those with no addiction and in cases with >10 years of addiction than in those with ≤ 10years of addiction. Our data suggest that tobacco in both smoked and smokeless forms is the most importantrisk factor for both development and prognosis of HNSCCs and may be a major source of field cancerization onthe head and neck epithelium in the eastern Indian population.     

The molecular mechanism of human papillomavirus-induced carcinogenesis in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. Recently, the incidence of oropharyngeal cancer (OPC) has increased markedly in comparison to that of HNSCC, which is associated with the use of tobacco or alcohol or both. This increase has resulted mainly from the global rise in the number of human papillomavirus (HPV)-related oropharyngeal cancers (HPV-OPCs). HPV-OPC has several unique characteristics, including presentation in younger patients, better response rates to treatment, and better prognosis compared to alcohol- and smoking-related HNSCC. HPV infection status is now an independent prognostic factor for survival in patients with OPC. In general, HPV oncoproteins E6 and E7 are the primary viral factors responsible for the initiation and progression of HPV-related cancers via the inactivation of p53 and pRb. However, alterations in additional factors, including genomic instability, HPV DNA integration, and epigenetic alterations, could be equally important for neoplastic transformation and tumor progression. The impact of genomic instability and external environmental factors on the initiation of cervical cancer development through high-risk HPV infection has been well characterized, although less is known about the mechanism underlying HPV-induced carcinogenesis in HNSCC. This review provides an overview of the biology and molecular mechanisms of HPV-related cancers, including a particular focus on several recent studies on the comprehensive characterization of genomic alterations in HPV-associated HNSCC.