Clinical implications of human papillomavirus in head and neck cancers

Transoral laser microsurgery for laryngeal cancer: a primer and review of laser dosimetry

Transoral laser microsurgery (TLM) is an emerging technique for the management of laryngeal and other head and neck malignancies. It is increasingly being used in place of traditional open surgery because of lower morbidity and improved organ preservation. Since the surgery is performed from the inside working outward as opposed to working from the outside in, there is less damage to the supporting structures that lie external to the tumor. Coupling the laser to a micromanipulator and a microscope allows precise tissue cutting and hemostasis; thereby improving visualization and precise ablation. The basic approach and principles of performing TLM, the devices currently in use, and the associated dosimetry parameters will be discussed. The benefits of using TLM over conventional surgery, common complications and the different settings used depending on the location of the tumor will also be discussed. Although the CO₂ laser is the most versatile and the best-suited laser for TLM applications, a variety of lasers and different parameters are used in the treatment of laryngeal cancer. Improved instrumentation has lead to an increased utilization of TLM by head and neck cancer surgeons and has resulted in improved outcomes. Laser energy levels and spot size are adjusted to vary the precision of cutting and amount of hemostasis obtained.

Interventions for the treatment of oral cavity and oropharyngeal cancer: chemotherapy

BACKGROUND

Oral cavity and oropharyngeal cancers are frequently described as part of a group of oral cancers or head and neck cancer. Treatment of oral cavity cancer is generally surgery followed by radiotherapy, whereas oropharyngeal cancers, which are more likely to be advanced at the time of diagnosis, are managed with radiotherapy or chemoradiation. Surgery for oral cancers can be disfiguring and both surgery and radiotherapy have significant functional side effects, notably impaired ability to eat, drink and talk. The development of new chemotherapy agents, new combinations of agents and changes in the relative timing of surgery, radiotherapy, and chemotherapy treatments may potentially bring about increases in both survival and quality of life for this group of patients.

OBJECTIVES

To determine whether chemotherapy, in addition to radiotherapy and/or surgery for oral cavity and oropharyngeal cancer results in improved survival, disease free survival, progression free survival, locoregional control and reduced recurrence of disease. To determine which regimen and time of administration (induction, concomitant or adjuvant) is associated with better outcomes.

SEARCH STRATEGY

Electronic searches of the Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE, EMBASE, AMED were undertaken on 28th July 2010. Reference lists of recent reviews and included studies were also searched to identify further trials.

SELECTION CRITERIA

Randomised controlled trials where more than 50% of participants had primary tumours in the oral cavity or oropharynx, and which compared the addition of chemotherapy to other treatments such as radiotherapy and/or surgery, or compared two or more chemotherapy regimens or modes of administration, were included.

DATA COLLECTION AND ANALYSIS

Trials which met the inclusion criteria were assessed for risk of bias using six domains: sequence generation, allocation concealment, blinding, completeness of outcome data, selective reporting and other possible sources of bias. Data were extracted using a specially designed form and entered into the characteristics of included studies table and the analysis sections of the review. The proportion of participants in each trial with oral cavity and oropharyngeal cancers are recorded in Additional Table 1.

MAIN RESULTS

There was no statistically significant improvement in overall survival associated with induction chemotherapy compared to locoregional treatment alone in 25 trials (hazard ratio (HR) of mortality 0.92, 95% confidence interval (CI) 0.84 to 1.00). Post-surgery adjuvant chemotherapy was associated with improved overall survival compared to surgery +/- radiotherapy alone in 10 trials (HR of mortality 0.88, 95% CI 0.79 to 0.99), and there was an additional benefit of adjuvant concomitant chemoradiotherapy compared to radiotherapy in 4 of these trials (HR of mortality 0.84, 95% CI 0.72 to 0.98). Concomitant chemoradiotherapy resulted in improved survival compared to radiotherapy alone in patients whose tumours were considered unresectable in 25 trials (HR of mortality 0.79, 95% CI 0.74 to 0.84). However, the additional toxicity attributable to chemotherapy in the combined regimens remains unquantified.

AUTHORS' CONCLUSIONS

Chemotherapy, in addition to radiotherapy and surgery, is associated with improved overall survival in patients with oral cavity and oropharyngeal cancers. Induction chemotherapy is associated with a 9% increase in survival and adjuvant concomitant chemoradiotherapy is associated with a 16% increase in overall survival following surgery. In patients with unresectable tumours, concomitant chemoradiotherapy showed a 22% benefit in overall survival compared with radiotherapy alone.

Human papillomavirus seropositivity synergizes with MDM2 variants to increase the risk of oral squamous cell carcinoma

The increasing incidence of oral squamous cell carcinoma (OSCC) in young adults has been associated with sexually transmitted infections of human papillomavirus (HPV), particularly HPV16. Given the roles of p53 in tumor suppression and of HPV E6 and MDM2 oncoproteins in p53 degradation, we evaluated HPV16 L1 seropositivity and MDM2 promoter variants to examine their possible associations with OSCC risk in a case-control study of 325 patients and 335 cancer-free matched controls. Compared with individuals having MDM2-rs2279744 GT or GG genotypes and HPV16 L1 seronegativity, the TT genotype and HPV16 L1 seronegativity were found to be associated with an odds ratio (OR) of 1.25 [95% confidence interval (CI), 1.06-2.19] for OSCC risk, and GT/GG and HPV16 L1 seropositivity were associated with an OR of 2.81 (95% CI, 1.67-4.74). For those with both the TT genotype and HPV16 L1 seropositivity, the associated OR was 5.57 (95% CI, 2.93-10.6). Similar results were observed for the MDM2-rs937283 polymorphism. Moreover, there was a borderline significant or significant interaction between the individual or combined MDM2 genotypes of the two polymorphisms and HPV16 L1 seropositivity (P(int) = 0.060 for MDM2-rs2279744, P(int) = 0.009 for MDM2-rs937283, and P(int) = 0.005 for the combined MDM2 genotypes) on risk of OSCC. Notably, that effect modification was particularly pronounced in never smokers and never drinkers, and for oropharyngeal as opposed to oral cavity cancer. Taken together, our results indicate that the risk of OSCC associated with HPV16 L1 seropositivity is modified by MDM2 promoter polymorphisms.

Human papillomavirus: changing paradigms in oropharyngeal cancer

The human papillomavirus (HPV) has recently been identified as an important etiologic agent in the development of squamous cell carcinoma of the oropharynx. The HPV- associated cancers appear to have a different biology than the HPV-negative cancers, and affect a population that is more likely to be young, male, Caucasian, and nonsmoking. More importantly, however, is the recognition that patients with an HPV-associated oropharyngeal cancer have a distinctly better survival after treatment than those patients with HPV-negative tumors, although their prognosis is significantly worse if there is a history of tobacco abuse. HPV-associated oropharynx cancer should be recognized as a new biologic entity and studied separately from HPV-negative cancers in future clinical trials. The potential for disease prevention with the use of the current HPV vaccines is discussed.

HPV-positive/p16-positive/EBV-negative nasopharyngeal carcinoma in white North Americans

BACKGROUND

Human papillomavirus (HPV) has been detected in keratinizing nasopharyngeal carcinomas (NPCs); however, the relationship between HPV and Epstein-Barr virus (EBV) among whites with nonkeratinizing NPCs remains unclear. The HPV, p16, and EBV status was examined in current University of Michigan patients with NPC.

METHODS

From 2003 to 2007, 89 patients, 84 with oropharyngeal cancer (OPC) and 5 with NPC, were enrolled in an organ-sparing trial. Biopsy tissues from all 89 patients were evaluated for HPV and p16 expression. A separate HPV analysis of the 84 OPC patients is in progress. Among the patients with NPC, tumor tissue was also analyzed for EBV-encoded RNA (EBER).

RESULTS

Five of 89 patients (5.6%) had NPC, all with nonkeratinizing histology. The 4 white patients with NPC were HPV(+) (subtype-16, subtype-18 [2 patients], and subtype-59)/p16(+)/EBER(-). One Asian patient with NPC had an HPV(-)/p16(-)/EBER(+) NPC tumor that developed distant metastases.

CONCLUSION

We postulate that HPV may be the etiologic factor in some EBV-negative, nonkeratinizing NPCs among whites.

High incidence of oral squamous cell carcinoma independent of HPV infection after allogeneic hematopoietic SCT in Taiwan

Hematopoietic SCT (HSCT) is a well-recognized therapeutic procedure to prolong life and cure patients with life-threatening hematological malignancies; however, the risk of developing secondary carcinoma may increase in long-term survivors. The objective of this study was to determine the incidence and risk factors for secondary squamous carcinoma after HSCT. Between 1984 and 2004, 170 allogeneic HSCT recipients aged >15 years, who had survived for >5 years were enrolled. Demographic data and the characteristics of secondary carcinoma were collected and analyzed for the determination of the incidence and risk of developing secondary carcinoma. Eight patients developed secondary carcinoma, including five oral squamous cell carcinomas, one esophageal, one gastric and one ovarian carcinoma, but no cutaneous carcinomas were detected at a median follow-up of 14.1 years (range, 5.1-23.3 years) after HSCT. The accrual 10-year cumulative incidence of secondary carcinoma was 2.89%. In univariate and multivariate analyses, chronic GVHD and age >40 years at the time of HSCT were both significant risk factors independently associated with the development of secondary carcinoma. Thus, the occurrence of secondary carcinoma is one of the late complications in patients undergoing HSCT. Oral squamous cell carcinoma was more common in our patients after HSCT, indicating the need for lifelong surveillance of the oral cavity. Moreover, because of the relatively long latency in developing secondary carcinoma, extended follow-up is required for a thorough understanding of the incidence and characteristics of secondary carcinoma after HSCT.

Methods for HPV detection in exfoliated cell and tissue specimens

Given the causal involvement of high-risk human papillomaviruses (HPVs) in cervical cancer and a subset of squamous cell carcinomas of other anogenital regions as well as the oropharynx, much attention has been focused on the development and application of HPV detection assays. HPV detection assays are almost exclusively based on the detection of viral nucleic acids, mostly viral DNA. The HPV detection methods that are nowadays in use can broadly be subdivided into target amplification methods and signal amplification methods. In this review, several principles of various methodologies are explained and examples of some commonly used HPV detection assays are given. In addition, attention is paid to the use of HPV assays for detecting clinically meaningful HPV infections, i.e. infections related to (pre)cancerous lesions, e.g. cervical cancer screening purposes. For the latter, it is important that HPV tests are clinically validated according to validation strategies as outlined in guidelines.

Never-smokers, never-drinkers: unique clinical subgroup of young patients with head and neck squamous cell cancers

BACKGROUND

Young patients represent an increasing subgroup with head and neck cancer.

METHODS

Patients between 18 and 39 years of age with newly diagnosed and previously untreated squamous cell cancers were identified.

RESULTS

Seventy-eight patients met the selection criteria: 28 patients were never-smokers/never-drinkers (NSNDs), and 50 patients reported tobacco or alcohol abuse (smokers and/or drinkers [SD]). NSND patients were diagnosed at a younger median age (31.5 years vs 35.5 years, p = .007), were more likely to be female (75% vs 30%, p < .001) and white (89% vs 60%, p = .006), and were more likely to have tumors of the oral tongue (57% vs 24%, p = .003) and T1 disease (47% vs 20%, p = .01). There was no difference in 10-year relapse-free survival, but a suggestion of improved 10-year overall survival for NSND patients (71% vs 46%, p = .10).

CONCLUSIONS

Young patients with head and neck squamous cell carcinoma (HNSCC) appear to have unique clinical profiles based on history of alcohol and tobacco abuse.

Trends in the survival of patients diagnosed with cancers of the lip, oral cavity, and pharynx in the Nordic countries 1964-2003 followed up to the end of 2006

BACKGROUND

This is the first comprehensive population-based study on relative survival of lip, oral cavity and pharyngeal cancer in the Nordic countries.

MATERIAL AND METHODS

Relative survival of patients with cancers of the lip, oral cavity, and pharynx diagnosed in the Nordic countries in 1964-2003 and followed up to the end of 2006 was studied and contrasted with trends in incidence and mortality.

RESULTS

There are marked differences in incidence between countries and over time. The stability of the relative survival ratios gives support to the hypothesis that the incidence differences are more likely to be real and not materially affected by differences in definitions and coding. Of particular note are the steep rises in pharyngeal cancer incidence in Denmark in both sexes. Survival has only moderately improved over time and has tended to be slightly higher in females than males.

CONCLUSIONS

Co-morbidity caused by smoking and high alcohol consumption are likely to be partially responsible for differences between countries. Advances in therapy and standards of care are also likely to have played a role in the increasing survival trends.

Time trends in pharyngeal cancer incidence in Norway 1981-2005: a subsite analysis based on a reabstraction and recoding of registered cases

OBJECTIVE

Incidence rates of oropharyngeal squamous cell carcinoma (SCC) have been reported to be increasing in several countries in recent decades, contrasting with trends of SCCs diagnosed in neighboring anatomical sites. We investigated whether changes in classification systems and/or coding/registration practices might explain the trends in Norway, focusing on changes in oropharyngeal cancer.

METHODS

Trends in cancers of the oropharynx, base of tongue, nasopharynx, hypopharynx were graphically presented for the period 1981-2005, before and after recoding. Age-period-cohort and future prediction models were fitted to oropharyngeal SCC incidence.

RESULTS

A total of 85 (3.7%) of the 2315 pharyngeal cancers required recoding. Rates of oropharyngeal cancer in Norway were consistently two to three times higher in men, with rapid increases in both men (5% per annum) and women (4.2% per annum). Assuming generational effects, male cohorts born 1915-1950 were at increasingly higher risk of the disease. The number of oropharyngeal cancer cases is expected to double in Norway by 2020.

CONCLUSIONS

The trends were not considered materially biased by potential artefacts. The increasingly higher proportion of oropharyngeal SCC cancers is more likely explained by other factors, including an increasing high-risk HPV prevalence among recent cohorts. These results will likely have consequences on treatment and health care provision in the near future.

Intensity-modulated chemoradiotherapy aiming to reduce dysphagia in patients with oropharyngeal cancer: clinical and functional results

PURPOSE

To assess clinical and functional results of chemoradiotherapy for oropharyngeal cancer (OPC), utilizing intensity-modulated radiotherapy (IMRT) to spare the important swallowing structures to reduce post-therapy dysphagia.

PATIENTS AND METHODS

This was a prospective study of weekly chemotherapy (carboplatin dosed at one times the area under the curve [AUC, AUC 1] and paclitaxel 30 mg/m(2)) concurrent with IMRT aiming to spare noninvolved parts of the swallowing structures: pharyngeal constrictors, glottic and supraglottic larynx, and esophagus as well as the oral cavity and major salivary glands. Swallowing was assessed by patient-reported Swallowing and Eating Domain scores, observer-rated scores, and videofluoroscopy (VF) before therapy and periodically after therapy through 2 years.

RESULTS

Overall, 73 patients with stages III to IV OPC participated. At a median follow-up of 36 months, 3-year disease-free and locoregional recurrence-free survivals were 88% and 96%, respectively. All measures of dysphagia worsened soon after therapy; observer-rated and patient-reported scores recovered over time, but VF scores did not. At 1 year after therapy, observer-rated dysphagia was absent or minimal (scores 0 to 1) in all patients except four: one who was feeding-tube dependent and three who required soft diet. From pretherapy to 12 months post-therapy, the Swallowing and Eating Domain scores worsened on average (+/- standard deviation) by 10 +/- 21 and 13 +/- 19, respectively (on scales of 0 to 100), and VF scores (on scale of 1 to 7) worsened from 2.9 +/- 1.5 (mild dysphagia) to 4.1 +/- 0.9 (mild/moderate dysphagia).

CONCLUSION

Chemoradiotherapy with IMRT aiming to reduce dysphagia can be performed safely for OPC and has high locoregional tumor control rates. On average, long-term patient-reported, observer-rated, and objective measures of swallowing were only slightly worse than pretherapy measures, representing potential improvement compared with previous studies.

Induction chemotherapy in the management of head and neck cancer

The strategy of induction chemotherapy prior to planned definitive local therapy for head and neck squamous cell carcinoma has been studied for over 30 years, and appears to have a role in select clinical situations. Here we review landmark studies regarding induction chemotherapy, both in the pre-taxane era and in the current taxane era, and we address some of the unresolved questions regarding the role of induction chemotherapy in head and neck cancer.

Beyond cervical cancer: burden of other HPV-related cancers among men and women

Human papillomavirus (HPV) infection is a necessary cause of cervical cancer, and is etiologically associated with a subset of cancers of the anus, oropharynx, penis, vagina, and vulva. Current data indicate that HPV infection is potentially associated with 90%-93% of anal cancers, 12%-63% of oropharyngeal cancers, 36%-40% of penile cancers, 40%-64% of vaginal cancers, and 40%-51% of vulvar cancers. HPV infection accounts for up to 492,800 cervical cancers and 97,215 cases of noncervical HPV-related cancers worldwide during 2002, including up to 50,780 cancers among men (13,485 anal cancers, 26,775 oropharyngeal cancers, and 10,520 penile cancers) and up to 46,435 cancers among women (14,787 anal cancers, 6,048 oropharyngeal cancers, and 25,600 vaginal/vulvar cancers). In the United States annually (1998-2003), up to 10,846 cervical cancers, 4,753 noncervical cancers among men, and 4,128 noncervical cancers among women are potentially attributable to HPV infection. Incidence rates for cervical cancer have declined significantly during the past 30 years in the United States, consistent with the success of Pap smear screening. However, incidence rates for anal, oropharyngeal, and vulvar cancers have increased substantially in recent years. The high proportion of cervical and noncervical cancers caused by HPV types 16 and 18, that is, 70%-76% for cervical cancers and 63%-95% for noncervical cancers, underscores the potential for prevention of a majority of cervical as well as noncervical HPV-related cancers through prophylactic HPV vaccination.

Developments in therapeutic human papillomavirus vaccination

Much progress has been made in the prevention and therapy of premalignant and malignant dysplasia caused by human papillomavirus by encouraging screening programs and recently by introducing preventive vaccines. To further reduce the worldwide burden of HPV-associated cancer supplementation of the established therapies with immunotherapeutic methods would have the potential for significant impact. Dysplastic epithelial lesions and cancer of the anogenital and the oropharyngeal region show strong association with HPV. Therefore cervical carcinoma and HPV-associated squamous cell carcinoma of the head and neck differ from most other malignancies in that they harbour HPV-derived antigens. Expression of the viral oncogenes is mandatory to maintain the cancerous phenotype. These antigens are unique to the tumour and attractive targets for "proof of concept" studies in the development of therapeutic vaccines showing the general applicability of tumour vaccination and prove the correlation of immune response and clinical response. To date numerous clinical trials have been performed with candidate vaccines predominantly testing the efficacy for cervical cancer and its precursors. Although a naturally induced anti-HPV T cell response in patients was shown, clinical success of therapeutic vaccines was sparse. This may be attributed to immunosuppression, immunoselection, and immunoediting by the tumour cells. Factors of the individual that led to the failure of autonomous clearance of the initial infection may also contribute. Overriding this failure, reversing immunosuppression and application of vaccines in early stages of the disease is the key task for the future. The aim of this article is to summarize recent developments of therapeutic vaccines and discuss obstacles that hinder their success.

The gastric cardia is not a target for human papillomavirus-induced carcinogenesis

BACKGROUND

Thousands of people in central Asia die every year from gastric cardia adenocarcinoma (GCA). GCA arises in the transformation zone between the esophagus and the stomach, similar to cervical and oropharyngeal carcinoma, which arise in areas with transformation zone characteristics. The analogous biology of the gastric cardia to the cervix and oropharynx, where human papillomavirus (HPV) is known to cause cancer, raises the possibility that GCA could be a HPV-associated cancer. Given the availability of an effective HPV vaccine and its potential to prevent HPV-associated cancer, we decided to evaluate the prevalence of HPV DNA in GCA.

METHODS

We collected tumor tissue from 144 histopathologically confirmed GCA patients at Yaocun Commune Hospital (Linxian, China), with rigorous attention to prevent DNA contamination. We tested for the presence of HPV DNA in fresh-frozen tumor specimens using PCR with sensitive L1-, E6-, and E7-based primers.

RESULTS

DNA was adequate, as indicated by beta-globin positivity, in 108 cases. Of these, all (100%; 95% confidence interval, 97-100%) were negative for HPV DNA.

CONCLUSIONS

These results suggest that HPV does not contribute to gastric cardia carcinogenesis in north central China.

IMPACT

Because GCA does not seem to be a HPV-associated cancer, prophylactic HPV vaccination is unlikely to affect rates of GCA in China.

Bcl2 and human papilloma virus 16 as predictors of outcome following concurrent chemoradiation for advanced oropharyngeal cancer

PURPOSE

Oropharyngeal squamous cell carcinoma (OPSCC) associated with human papilloma virus (HPV) is rapidly growing in incidence. Despite better prognosis than OPSCC associated with traditional risk factors, treatment failure still occurs in a significant proportion of patients. We had identified the antiapoptotic protein Bcl2 as a marker for poor outcome in advanced OPSCC treated with concurrent chemoradiation. To determine whether Bcl2 and HPV together might further characterize treatment response, we examined whether the prognostic value of Bcl2 was independent of HPV status.

EXPERIMENTAL DESIGN

Pretreatment tumor biopsies from 68 OPSCC patients were tested for HPV by in situ hybridization and were immunostained for Bcl2 to evaluate relations with disease-free (DFS) and overall survival following platin-based concurrent chemoradiation. Median follow-up among surviving patients was 47 months (range, 10-131 months).

RESULTS

Bcl2 and HPV independently predicted DFS and overall survival. Hazard ratios (with 95% confidence interval) for positive versus negative status in bivariate Cox proportional hazard analysis of DFS were 6.1 (1.8-21) for Bcl2 and 0.11 (0.035-0.37) for HPV. Only 1 of 32 HPV-positive/Bcl2-negative tumors recurred. Pretreatment Bcl2 expression was specifically associated with distant metastasis; five of six distant metastases occurred in the <40% of patients whose primary tumors were Bcl2 positive.

CONCLUSIONS

Independent of HPV status, pretreatment Bcl2 expression identifies a subset of OPSCC patients having increased risk of treatment failure, particularly through distant metastasis, after concurrent chemoradiation. Considering HPV and Bcl2 together should help in devising better personalized treatments for OPSCC.

Clinical effect of human papillomavirus genotypes in patients with cervical cancer undergoing primary radiotherapy

PURPOSE

To study the prognostic value of the human papillomavirus (HPV) genotypes in cervical cancer patients undergoing radiotherapy.

PATIENTS AND METHODS

A total of 1,010 patients with cervical cancer after radiotherapy between 1993 and 2000 were eligible for this study. The HPV genotypes were determined by a genechip, which detects 38 types of HPV. The patient characteristics and treatment outcomes were analyzed using the Cox regression hazard model and classification and regression tree decision tree method.

RESULTS

A total of 25 genotypes of HPV were detected in 992 specimens (98.2%). The leading 8 types were HPV16, 58, 18, 33, 52, 39, 31, and 45. These types belong to two high-risk HPV species: alpha-7 (HPV18, 39, 45) and alpha-9 (HPV16, 31, 33, 52, 58). Three HPV-based risk groups, which were independent of established prognostic factors, such as International Federation of Gynecology and Obstetrics stage, age, pathologic features, squamous cell carcinoma antigen, and lymph node metastasis, were associated with the survival outcomes. The high-risk group consisted of the patients without HPV infection or the ones infected with the alpha-7 species only. Patients co-infected with the alpha-7 and alpha-9 species belonged to the medium-risk group, and the others were included in the low-risk group.

CONCLUSION

The results of the present study have confirmed the prognostic value of HPV genotypes in cervical cancer treated with radiotherapy. The different effect of the alpha-7 and alpha-9 species on the radiation response deserves additional exploration.

Recent advances in managing human papillomavirus-positive oropharyngeal tumors

Human papillomavirus (HPV) is detected in a subset of patients with head and neck squamous cell carcinoma, most frequently in tumors in the Waldeyer's ring (palatine tonsil and base of tongue). Several studies suggest that patients with HPV-positive tumors have better survival with either concurrent chemoradiation therapy or surgery followed by radiation compared with HPV-negative patients. However, some possible confounding clinicopathologic variables may challenge the validity of this statement, for example, some authors used the TNM (tumor, node, metastasis) grouping stage while others used the primary tumor (T stage), and other studies have demonstrated that tumors with advanced T stage were less likely to be infected with HPV. A large clinical trial with stratification of patients according to all known tumor prognostic factors is crucial to solve the question.

Low prevalence of human papillomavirus in oral cavity carcinomas

BACKGROUND

Increasing evidence shows that Human Papillomavirus (HPV) is preferentially associated with some head and neck squamous cell carcinomas (HNSCCs), with variable infection rates reported.

METHODS

We assessed HPV involvement in HNSCC using the Roche Linear Array HPV Genotyping Test, which can detect 37 different HPV types. We examined the prevalence of HPV infection in 92 HNSCCs (oropharynx, oral cavity, and other HNSCC sites).

RESULTS

HPV was frequently detected in oropharyngeal cancers (OPCs) (16/22, 73%), but was uncommon in oral cavity cancers (2/53, 4%), and in other HNSCC subsites (1/17, 6%). HPV positive tumors were associated with patients that were 40-60 years old (p = 0.02), and node positive (p = < 0.0001). HPV 16 was the most prevalent type, but other types detected included 6, 18, 33, 35, 45, and 52/58.

CONCLUSION

Our results show that in contrast to oropharyngeal cancers, oral cancers and other HNSCCs infrequently harbor HPV.

Tobacco use in human papillomavirus-positive advanced oropharynx cancer patients related to increased risk of distant metastases and tumor recurrence

PURPOSE

The goal of this study was to examine the effect of tobacco use on disease recurrence (local/regional recurrence, distant metastasis, or second primary) among patients with human papillomavirus (HPV)-positive squamous cell carcinoma of the oropharynx (SCCOP) following a complete response to chemoradiation therapy.

EXPERIMENTAL DESIGN

Between 1999 and 2007, 124 patients with advanced SCCOP (86% with stage IV) and adequate tumor tissue for HPV analysis who were enrolled in one of two consecutive University of Michigan treatment protocols were prospectively included in this study. Patients were categorized as never-, former, or current tobacco users. The primary end points were risk of disease recurrence and time to recurrence; secondary end points were disease-specific survival and overall survival.

RESULTS

One hundred and two patients (82.3%) had HPV-positive tumors. Over two thirds (68%) of patients with HPV-positive tumors were tobacco users. Among HPV-positive patients, current tobacco users were at significantly higher risk of disease recurrence than never-tobacco users (hazard ratio, 5.2; confidence interval, 1.1-24.4; P = 0.038). Thirty-five percent of HPV-positive ever tobacco users recurred compared with only 6% of HPV-positive never users and 50% of HPV-negative patients. All HPV-negative patients were tobacco users and had significantly shorter times to recurrence (P = 0.002), and had reduced disease-specific survival (P = 0.004) and overall survival (P < 0.001) compared with HPV-positive patients. Compared with HPV-positive never-tobacco users, those with a tobacco history showed a trend for reduced disease-specific survival (P = 0.064) but not overall survival (P = 0.221).

CONCLUSIONS

Current tobacco users with advanced, HPV-positive SCCOP are at higher risk of disease recurrence compared with never-tobacco users.

Human papillomavirus (HPV)-positive tonsillar carcinomas are frequent and have a favourable prognosis in males in Norway

CONCLUSIONS

This study confirms a high prevalence of human papillomavirus (HPV)-positive tonsillar tumours (52%). The survival of the HPV-positive group was significantly better in males.

OBJECTIVES

We assessed the prevalence of HPV in 137 patients with tonsillar carcinomas, measured the p53- and Ki-67-positive tumour cell fractions and correlated the results with clinical variables.

PATIENTS AND METHODS

Tumour DNA from patients with squamous cell carcinoma of the tonsillar region was amplified by PCR and sequenced for detection of HPV subtypes.

RESULTS

HPV was found in 71/137 (52%) of the tumours; HPV-16 was the most frequent subtype (87%). HPV positivity did not correlate with gender, stage, T- and N categories, Ki-67 expression or p53 positivity. The HPV-positive group had a significantly better survival (p < 0.01) compared with the HPV-negative group in males. In a multivariate analysis HPV status gave prognostic information in addition to the earlier established factors, i.e. age, gender and stage (p < 0.05).

Sexual behaviours and the risk of head and neck cancers: a pooled analysis in the International Head and Neck Cancer Epidemiology (INHANCE) consortium

BACKGROUND

Sexual contact may be the means by which head and neck cancer patients are exposed to human papillomavirus (HPV).

METHODS

We undertook a pooled analysis of four population-based and four hospital-based case-control studies from the International Head and Neck Cancer Epidemiology (INHANCE) consortium, with participants from Argentina, Australia, Brazil, Canada, Cuba, India, Italy, Spain, Poland, Puerto Rico, Russia and the USA. The study included 5642 head and neck cancer cases and 6069 controls. We calculated odds ratios (ORs) of associations between cancer and specific sexual behaviours, including practice of oral sex, number of lifetime sexual partners and oral sex partners, age at sexual debut, a history of same-sex contact and a history of oral-anal contact. Findings were stratified by sex and disease subsite.

RESULTS

Cancer of the oropharynx was associated with having a history of six or more lifetime sexual partners [OR = 1.25, 95% confidence interval (CI) 1.01, 1.54] and four or more lifetime oral sex partners (OR = 2.25, 95% CI 1.42, 3.58). Cancer of the tonsil was associated with four or more lifetime oral sex partners (OR = 3.36, 95 % CI 1.32, 8.53), and, among men, with ever having oral sex (OR = 1.59, 95% CI 1.09, 2.33) and with an earlier age at sexual debut (OR = 2.36, 95% CI 1.37, 5.05). Cancer of the base of the tongue was associated with ever having oral sex among women (OR = 4.32, 95% CI 1.06, 17.6), having two sexual partners in comparison with only one (OR = 2.02, 95% CI 1.19, 3.46) and, among men, with a history of same-sex sexual contact (OR = 8.89, 95% CI 2.14, 36.8).

CONCLUSIONS

Sexual behaviours are associated with cancer risk at the head and neck cancer subsites that have previously been associated with HPV infection.

Is the improved prognosis of p16 positive oropharyngeal squamous cell carcinoma dependent of the treatment modality?

The incidence of human papilloma virus (HPV) induced oropharyngeal squamous cell carcinoma (OPSCC) increases in the western countries. These OPSCC show distinct molecular characteristics and are characterized by an overexpression of p16, considered a surrogate marker for HPV infection. When compared to patients with p16 negative OPSCC, patients with HPV induced p16 positive OPSCC show a significantly better prognosis, which is reported to be caused by increased radiosensitivity. The objective of the present study was to analyze the impact of p16 expression status on the prognosis of OPSCC treated by either radiotherapy (RT) or primary surgery. Results are based upon a tissue microarray (TMA) of 365 head neck squamous cell carcinomas (HNSCC) including 85 OPSCC with clinico-pathological and follow-up data. p16 positivity correlated significantly with oropharyngeal tumor localization (p < 0.001). Patients with p16 positive OPSCC exhibited a significantly better overall survival than those with p16 negative tumors (p = 0.007). In a multivariate analysis, survival benefit of patients with p16 positive OPSCC was independent of clinico-pathological parameters such as cT and cN classification and treatment modality. The improved prognosis of p16 positive OPSCC is found after RT as well as after surgery.

Advances and Perspectives in the Molecular Diagnosis of Head and Neck Cancer

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is a debilitating and lethal disease. Despite significant advances in radiotherapy and surgical management, the 5-year survival rate for head and neck cancer has remained a dismal 50%. Advances in early detection have been made, but to improve patient outcomes better biomarkers and targeted therapeutic agents are needed. Novel biomarkers can improve early detection and provide data to optimize therapeutic strategy and patient survival, and could lead to potentially effective targeted therapies. OBJECTIVE: Report the advances in the discovery of novel biomarkers for HNSCC, and review the potential utility of biomarkers in the molecular diagnosis of HNSCC. METHODS: A review of the English literature (PubMed) from 1980 to 2009. RESULTS/CONCLUSION: Currently the most widely accepted biomarker for HNSCC is high risk HPV status. EGFR is another promising biomarker, however, further research is necessary to determine its prognostic benefit. A large number of promising biomarker candidates are currently being evaluated including epigenetic, expression, and genomic based markers. Studies to validate the sensitivity and specificity of these biomarkers in clinical samples from adequately powered prospective cohorts are needed for successful translation of these findings into potential molecular diagnostic, prognostic, and therapeutic biomarkers for HNSCC.

Association of cystic neck metastases and human papillomavirus-positive oropharyngeal squamous cell carcinoma

Human papillomavirus is an established cause of oropharyngeal squamous cell carcinoma. Similar to cervical cancer, these cancers are usually caused by high-risk human papillomavirus types 16 and 18 and are associated with high-risk sexual behaviors. Human papillomavirus-associated oropharyngeal squamous cell carcinoma typically affects the palatine and lingual tonsils and frequently results in cystic neck metastases. The histopathology of this subset of head and neck squamous cell carcinoma is unique and typically characterized by poorly differentiated, nonkeratinizing morphology with a basaloid appearance. These tumors occur in younger patients and are more often seen in nonsmokers compared with conventional oral cavity and oropharyngeal squamous cell carcinomas. The incidence of human papillomavirus-associated squamous cell carcinoma is increasing. Recognition of this unique clinicopathologic subset of head and neck carcinoma is important because these patients typically respond more favorably to organ-sparing treatment modalities and have an improved prognosis.

Comparative prognostic value of HPV16 E6 mRNA compared with in situ hybridization for human oropharyngeal squamous carcinoma

PURPOSE

A significant proportion of oropharyngeal squamous cell carcinomas (OSCC) are associated with the human papilloma virus (HPV), particularly HPV16. The optimal method for HPV determination on archival materials however, remains unclear. We compared a quantitative real-time polymerase chain reaction (qRT-PCR) assay for HPV16 mRNA to a DNA in situ hybridization (ISH) method, and evaluated their significance for overall (OS) and disease-free (DFS) survival.

PATIENTS AND METHODS

Matched, archival biopsies from 111 patients with OSCC were evaluated for HPV16 using a qRT-PCR for E6 mRNA and ISH for DNA. Immunohistochemistry for p16, p53, and epidermal growth factor receptor were also performed.

RESULTS

HPV16 E6 mRNA was positive in 73 (66%) of 111 samples; ISH was positive in 62 of 106 samples (58%), with 86% concordance. P16 was overexpressed in 72 samples (65%), which was strongly associated with HPV16 status by either method. E6 mRNA presence or p16 overexpression were significantly associated with superior OS; E6 mRNA, HPV16 ISH, or p16 were all significantly associated with DFS. On multivariate analysis adjusted for age, stage, and treatment, positive E6 mRNA was the only independent predictor for superior OS; for DFS, p16 expression or HPV16 status determined by either method was significant.

CONCLUSION

The prevalence of HPV16 in OSCC ranges from 58% to 66%, in a recently treated Canadian cohort. Classification of HPV-positivity by HPV16 E6 mRNA, HPV16 ISH or p16 immunohistochemistry (IHC) is associated with improved DFS. However, the latter two assays are technically easier to perform; hence, HPV16 ISH or p16 IHC should become standard evaluations for all patients with OSCC.

Review of epidemiologic data on the debate over smokeless tobacco's role in harm reduction

Some tobacco researchers have argued that the European Union should remove its ban on a form of low-nitrosamine smokeless tobacco referred to as Swedish 'snus'. This argument has developed in to an international debate over the use of smokeless tobacco as a measure of harm reduction for smokers. Leading authorities in the USA have firmly stated that there is no safe tobacco - a message which does not allow for any discussion of comparative tobacco risks. This commentary is intended to review the origin of the controversy over Swedish 'snus', to examine briefly the meta-analysis on cancer risks by Peter Lee and Jan Hamling (published in July in BMC Medicine) and to discuss the anticipated direction of the debate on tobacco-harm reduction in the USA. We anticipate that much of the debate will shift from the discussion of epidemiologic data to the discussion of the marketing, health communication and economics of smokeless tobacco. While the Food and Drug Administration's newly approved authority over tobacco will undoubtedly affect the smokeless products, it may not be the sole determinant of harm reduction's fate in the USA. See associated research article by Lee and Hamling: http://www.biomedcentral.com/1741-7015/7/36.

Transcription factor AP-1 in esophageal squamous cell carcinoma: alterations in activity and expression during human Papillomavirus infection

Background

Esophageal squamous cell carcinoma (ESCC) is a leading cause of cancer-related deaths in Jammu and Kashmir (J&K) region of India. A substantial proportion of esophageal carcinoma is associated with infection of high-risk HPV type 16 and HPV18, the oncogenic expression of which is controlled by host cell transcription factor Activator Protein-1 (AP-1). We, therefore, have investigated the role of DNA binding and expression pattern of AP-1 in esophageal cancer with or without HPV infection.

Methods

Seventy five histopathologically-confirmed esophageal cancer and an equal number of corresponding adjacent normal tissue biopsies from Kashmir were analyzed for HPV infection, DNA binding activity and expression of AP-1 family of proteins by PCR, gel shift assay and immunoblotting respectively.

Results

A high DNA binding activity and elevated expression of AP-1 proteins were observed in esophageal cancer, which differed between HPV positive (19%) and HPV negative (81%) carcinomas. While JunB, c-Fos and Fra-1 were the major contributors to AP-1 binding activity in HPV negative cases, Fra-1 was completely absent in HPV16 positive cancers. Comparison of AP-1 family proteins demonstrated high expression of JunD and c-Fos in HPV positive tumors, but interestingly, Fra-1 expression was extremely low or nil in these tumor tissues.

Conclusion

Differential AP-1 binding activity and expression of its specific proteins between HPV - positive and HPV - negative cases indicate that AP-1 may play an important role during HPV-induced esophageal carcinogenesis.

Oncogenic activities of human papillomaviruses

Infectious etiologies for certain human cancers have long been suggested by epidemiological studies and studies with experimental animals. Important support for this concept came from the discovery by Harald zur Hausen's group that human cervical carcinoma almost universally contains certain "high-risk" human papillomavirus (HPV) types. Over the years, much has been learned about the carcinogenic activities of high-risk HPVs. These studies have revealed that two viral proteins, E6 and E7, that are consistently expressed in HPV-associated carcinomas, are necessary for induction and maintenance of the transformed phenotype. Hence, HPV-associated tumors are unique amongst human solid tumors in that they are universally caused by exposure to the same, molecularly defined oncogenic agents, and the molecular signal transduction pathways subverted by these viral transforming agents are frequently disrupted in other, non-virus-associated human cancers.

Association of p73 G4C14-to-A4T14 polymorphism with human papillomavirus type 16 status in squamous cell carcinoma of the head and neck in non-Hispanic whites

BACKGROUND

The tumor protein p73 interacts with the human papillomavirus type 16 (HPV-16) oncoproteins E6 and E7, and p73 variation may modify the interaction between p73 protein and HPV-16 oncogenic proteins and contribute to cellular malignant transformation.

METHODS

In this case-case comparison study, the authors analyzed HPV-16 status in tumor specimens and genotyped the p73 G4C14-to-A4T14 polymorphism using genomic DNA from blood of 202 non-Hispanic white patients with squamous cell carcinoma of the head and neck (SCCHN). Odds ratio (OR) and 95% confidence intervals (95% CIs) were calculated in univariate and multivariable logistic regression models to examine the association between the p73 polymorphism and HPV-16 status in SCCHN.

RESULTS

Compared with the p73 GC/GC genotype, the AT/AT and combined GC/AT + AT/AT variant genotypes were associated significantly with HPV-16-positive tumor status among patients with SCCHN (adjusted OR, 5.32; 95% CI, 1.32-21.4; adjusted OR, 1.91; 95% CI, 1.03-3.53, respectively). There was a significant dose-effect relation between the AT allele and HPV-16-positive tumor status in patients with SCCHN (trend test: P = .014). Moreover, the stratified analyses indicated that the association between HPV-16-positive tumor status and the combined p73 GC/AT + AT/AT genotypes was more pronounced among several subgroups of patients who were older, men, ever drinkers, and those with oropharyngeal cancer.

CONCLUSIONS

The p73 polymorphism was associated with HPV-16 status in SCCHN and may serve as a marker of positive HPV-16 tumor status in patients with SCCHN, particularly those with oropharyngeal cancer.

Immune therapy for cancer

Over the past decade, immune therapy has become a standard treatment for a variety of cancers. Monoclonal antibodies, immune adjuvants, and vaccines against oncogenic viruses are now well-established cancer therapies. Immune modulation is a principal element of supportive care for many high-dose chemotherapy regimens. In addition, immune activation is now appreciated as central to the therapeutic mechanism of bone marrow transplantation for hematologic malignancies. Advances in our understanding of the molecular interactions between tumors and the immune system have led to many novel investigational therapies and continue to inform efforts for devising more potent therapeutics. Novel approaches to immune-based cancer treatment strive to augment antitumor immune responses by expanding tumor-reactive T cells, providing exogenous immune-activating stimuli, and antagonizing regulatory pathways that induce immune tolerance. The future of immune therapy for cancer is likely to combine many of these approaches to generate more effective treatments.

The relationship between human papillomavirus status and other molecular prognostic markers in head and neck squamous cell carcinomas

PURPOSE

To evaluate the relationship between human papillomavirus (HPV) status and known prognostic makers for head and neck cancers including tumor hypoxia, epidermal growth factor receptor (EGFR) expression and intratumoral T-cell levels and to determine the prognostic impact of these markers by HPV status.

METHODS AND MATERIALS

HPV status in 82 evaluable head and neck squamous cell carcinomas patients was determined by pyrosequencing and related to p16(INK4a) staining and treatment outcomes. It was correlated with tumor hypoxia (tumor pO(2) and carbonic anhydrase [CAIX] staining), EGFR status, and intratumoral lymphocyte expression (CD3 staining).

RESULTS

Forty-four percent of evaluable tumors had strong HPV signal by pyrosequencing. There was a significant relationship between strong HPV signal and p16(INK4a) staining as well as oropharynx location. The strong HPV signal group fared significantly better than others, both in time to progression (TTP, p = 0.008) and overall survival (OS, p = 0.004) for all patients and for the oropharyngeal subset. Positive p16(INK4a) staining was associated with better TTP (p = 0.014) and OS (p = 0.00002). There was no relationship between HPV status and tumor pO(2) or CAIX staining. However, HPV status correlated inversely with EGFR reactivity (p = 0.0006) and directly with CD3(+) T-lymphocyte level (p = 0.03). Whereas CAIX and EGFR overexpression were negative prognostic factors regardless of HPV status, CD3(+) T-cell levels was prognostic only in HPV(-) tumors.

CONCLUSION

HPV status was a prognostic factor for progression and survival. It correlated inversely with EGFR expression and directly with T-cell infiltration. The prognostic effect of CAIX and EGFR expression was not influenced by HPV status, whereas intratumoral T-cell levels was significant only for HPV(-) tumors.

P21 Cip1/WAF1 expression is strongly associated with HPV-positive tonsillar carcinoma and a favorable prognosis

Human papillomavirus is involved in the carcinogenesis of tonsillar squamous cell carcinomas. Here, we investigated the expression and the prognostic value of key cell cycle proteins in the pRb and p53 pathways in both human papillomavirus type 16-positive and -negative tonsillar squamous cell carcinomas. Using immunohistochemistry, 77 tonsillar squamous cell carcinomas with known human papillomavirus type 16 status and clinical outcome were analyzed for expression of Ki67, p16(INK4A,) cyclin D1, pRb, p14(ARF), MDM2, p53, p21(Cip1/WAF1), and p27(KIP1). Results were correlated with each other and with clinical and demographic patient data. A total of 35% of tonsillar carcinomas harbored integrated human papillomavirus type 16 DNA and p16(INK4A) overexpression, both being considered essential features for human papillomavirus association. These tumors also showed the overexpression of p14(ARF) (P<0.0001) and p21(Cip1/WAF1) (P=0.001), and downregulation of pRb (P<0.0001) and cyclin D1 (P=0.027) compared with the human papillomavirus-negative cases. Univariate Cox regression analyses revealed a favorable survival rate for non-smokers (P=0.006), as well as for patients with T1-2 tumors (P<0.0001) or tumors showing low expression of cyclin D1 (P=0.028), presence of human papillomavirus and overexpression of p16(INK4A) (P=0.01), p14(ARF) (P=0.02) or p21(Cip1/WAF1) (P=0.004). In multivariate regression analyses, smoking and tumor size, as well as expression of cyclin D1 and p21(Cip1/WAF1), were found to be independent prognostic markers. We conclude that human papillomavirus positivity in tonsillar squamous cell carcinomas strongly correlates with p21(Cip1/WAF1) and p14(ARF) overexpression and downregulation of pRb and cyclin D1. In particular p21(Cip1/WAF1) overexpression is an excellent favorable prognosticator in tonsillar squamous cell carcinomas.

Genome-wide hypomethylation in head and neck cancer is more pronounced in HPV-negative tumors and is associated with genomic instability

Loss of genome-wide methylation is a common feature of cancer, and the degree of hypomethylation has been correlated with genomic instability. Global methylation of repetitive elements possibly arose as a defense mechanism against parasitic DNA elements, including retrotransposons and viral pathogens. Given the alterations of global methylation in both viral infection and cancer, we examined genome-wide methylation levels in head and neck squamous cell carcinoma (HNSCC), a cancer causally associated with human papilloma virus (HPV). We assayed global hypomethylation levels in 26 HNSCC samples, compared with their matched normal adjacent tissue, using Pyrosequencing-based methylation assays for LINE repeats. In addition, we examined cell lines derived from a variety of solid tumors for LINE and SINE (Alu) repeats. The degree of LINE and Alu hypomethylation varied among different cancer cell lines. There was only moderate correlation between LINE and Alu methylation levels, with the range of variation in methylation levels being greater for the LINE elements. LINE hypomethylation was more pronounced in HPV-negative than in HPV-positive tumors. Moreover, genomic instability, as measured by genome-wide loss-of-heterozygosity (LOH) single nucleotide polymorphism (SNP) analysis, was greater in HNSCC samples with more pronounced LINE hypomethylation. Global hypomethylation was variable in HNSCC. Its correlation with both HPV status and degree of LOH as a surrogate for genomic instability may reflect alternative oncogenic pathways in HPV-positive versus HPV-negative tumors.

Effect of HPV-associated p16INK4A expression on response to radiotherapy and survival in squamous cell carcinoma of the head and neck

PURPOSE

A subset of head and neck cancers is associated with the human papillomavirus (HPV). Viral infection is closely correlated with expression of p16(INK4A) in these tumors. We evaluated p16(INK4A) as a prognostic marker of treatment response and survival in a well-defined and prospectively collected cohort of patients treated solely with conventional radiotherapy in the Danish Head and Neck Cancer Group (DAHANCA) 5 trial.

PATIENTS AND METHODS

Immunohistochemical expression of p16(INK4A) was analyzed in pretreatment paraffin-embedded tumor blocks from 156 patients treated with conventional primary radiotherapy alone. The influence of p16(INK4A) status on locoregional tumor control, disease-specific survival, and overall survival after radiotherapy was evaluated.

RESULTS

p16(INK4A) positivity was found in 35 tumors (22%). Tumor-positivity for p16(INK4A) was significantly correlated with improved locoregional tumor control (5-year actuarial values 58% v 28%; P = .0005), improved disease-specific survival (72% v 34%; P = .0006), and improved overall survival (62% v 26%; P = .0003). In multivariate analysis, p16(INK4A) remained a strong independent prognostic factor for locoregional failure (hazard ratio [HR], 0.35; 95% CI, 0.19 to 0.64), disease-specific death (HR, 0.36; 95% CI, 0.20 to 0.64), and overall death (HR, 0.44; 95% CI, 0.28 to 0.68).

CONCLUSION

Expression of p16(INK4A) has a major impact on treatment response and survival in patients with head and neck cancer treated with conventional radiotherapy.

E6 and e7 gene silencing and transformed phenotype of human papillomavirus 16-positive oropharyngeal cancer cells

BACKGROUND

The E6 and E7 genes of human papillomavirus type 16 (HPV16) encode oncoproteins that bind and degrade p53 and retinoblastoma (pRb) tumor suppressors, respectively. We examined the effects of repressing E6 and E7 oncogene expression on the transformed phenotype of HPV16-positive oropharyngeal cancer cell lines.

METHODS

Human oropharyngeal squamous cell cancer 147T and 090 (harboring integrated HPV16 DNA) and 040T (HPV DNA-negative) cells were infected with retroviruses that expressed a short hairpin RNA (shRNA) targeting the HPV16 E6 and E7 genes or a scrambled-sequence control shRNA. Flow cytometry, terminal deoxynucleotidyltransferase-mediated UTP end-labeling assay, and immunoblotting for annexin V were used to assess apoptosis in shRNA-infected cell lines. Biochemical analysis involved quantitative real-time polymerase chain reaction analysis of p53- and pRb-target gene expression and immunoblotting for p53 and pRb protein expression.

RESULTS

In 147T and 090 cells, shRNA-mediated inhibition of HPV16 E6 and E7 expression reduced the E6 and E7 mRNA levels by more than 85% compared with control cells that expressed a scrambled-sequence shRNA. E6 and E7 repression resulted in restoration of p53 and pRB protein expression, increased expression of p53-target genes (p21 and FAS), decreased expression of genes whose expression is increased in the absence of functional pRb (DEK and B-MYB), and induced substantial apoptosis in 147T and 090 cells compared with the control shRNA-infected cells (from 13.4% in uninfected to 84.3% in infected 147T cells and from 3.3% in uninfected to 71.2% in infected 090 cells).

CONCLUSION

Repression of E6 and E7 oncogenes results in restoration of p53 and pRb suppressor pathways and induced apoptosis in HPV16-positive oropharyngeal squamous cell cancer cell lines.