Evaluation and application of a broad-spectrum polymerase chain reaction assay for human papillomaviruses in the screening of squamous cell tumours of the head and neck

OBJECTIVE: The results of studies analysing the prevalence of human papillomaviruses (HPVs) in squamous cell carcinomas of the head and neck region often vary depending on the different molecular biological methods applied. Focusing on the histomorphological criteria of HPV infections, the percentage of HPV-positive cancers should be higher than has been found in most studies. The aim of this study was to increase the detection spectrum of HPV polymerase chain reaction (PCR) screening using degenerate consensus primers. MATERIAL AND METHODS: To increase the sensitivity of the assay to one copy of HPV DNA per cell, a two-step PCR was carried out. The products were directly sequenced by means of a cycle sequencing approach. Seventy biopsies from squamous cell carcinomas of the upper aerodigestive tract were screened using the primer system. RESULTS: According to the PCR results, 0/2 carcinomas of the floor of the mouth or tongue, 7/16 biopsies of oropharyngeal cancers, 3/13 hypopharyngeal cancers, 13/34 squamous cell carcinomas of the larynx, 4/4 biopsies from carcinomas of the nasal cavity or paranasal sinuses and 1/1 squamous cell carcinoma of the parotid gland were positive. CONCLUSION: This broad-spectrum PCR can effectively detect HPV in head and neck cancers.     

Analysis of exon 2 of MTS1 in HPV-positive and HPV-negative tumors of the head and neck region

The aim of this study was to investigate the role of human papillomaviruses (HPVs) and alterations of p16INK4A in different squamous cell carcinomas (SCCs) of the head and neck region by screening these carcinomas for alterations in exon 2 of p16INK4A and for HPV DNA. A total of 42 samples of different SCCs of the head and neck were collected by biopsy or surgical resection. After DNA isolation, exon 2 of p16 was amplified and sequenced. HPV DNA was detected by applying a broad-spectrum polymerase chain reaction system. Mutations were found in 4 of our 42 samples. A total of 27 biopsies showed the presence of HPV DNA. All of the biopsies showing a mutation in exon 2 of CDK4 were HPV –positive, except the first biopsy of an oropharyngeal carcinoma. It might be possible that HPV infection and mutations in the exon 2 of CDK4 play a causal role in malignant transformation in a small number of squamous carcinomas of the head and neck region.     

EBV and not HPV sensitizes tobacco-associated head and neck cancer cell line FaDu to radiotherapy

Conclusion EBV radiosensitized the p53 mutant tobacco associated head and neck cell line, FaDu.

Objectives In the head and neck, HPV is a major risk factor associated with tonsil and base of tongue cancers, while a majority of undifferentiated nasopharyngeal cancers are positive for EBV. Clinically, head and neck tumors positive for HPV or EBV are more radiosensitive than tumors associated with tobacco and alcohol. This study aimed to evaluate whether viral infections can sensitize tobacco-associated head and neck squamous cell carcinoma cell line that harbors multiple mutations, especially TP53, to radiotherapy. Method Four FaDu cell lines (vector control – FaDu-DN; FaDu expressing HPV16 E6/E7 – FaDu-HPV; FaDu infected with EBV – FaDu-EBV; and FaDu-HPV infected with EBV – FaDu-HE) were evaluated for their radiation sensitivity using clonogenic assay. Cell cycle, protein expression, apoptosis, and cellular senescence were analyzed.

Results FaDu-EBV and FaDu-HE exhibited significantly increased radiosensitivity in comparison with the control cell line. Radiation-induced cell cycle arrest was altered in all cell lines expressing viral genes. The observed distribution of cells at G1 and S phases was associated with a significant increase in expression of p21 protein along with decreased levels of pAKT/AKT and pERK/ERK ratio (p?p?相似文献   

Association of Mycoplasma Hominis and head and neck cancer with unknown primary

IntroductionBeside HPV infection, there is currently no evidence of association between head and neck squamous cell carcinomas and microbial infections. We report the case of a cervical squamous cell carcinoma by Mycoplasma hominis.Case summaryA 20-year-old woman, consulted for a swelling on the left cervical side. Clinical examination found a large fixed mass. Biological tests found no evidence of infection. Biopsies of the cervical lesion diagnosed an HPV negative squamous cell carcinoma. Microbiological tests of 16sRNA identification showed the presence of Mycoplasma hominis in the 3 specimens. The patient was treated by induction chemotherapy associated to antibiotherapy, followed by chemo-radiotherapy.DiscussionThe present case suggests that oropharyngeal infection by Mycoplasma hominis might be more frequent than expected, that 16sRNA is an efficient technique to isolate this pathogen and finally that further studies are required to document its potential oncogenic role in head and neck squamous cell carcinomas.     

Occult nodal metastasis in head and neck carcinoma patients treated with chemoradiotherapy

Background and aimNeck lymph node metastasis plays an important role in the prognosis of patients with squamous cell carcinoma of the head and neck. The aim of this study was to evaluate the occult nodal metastasis in patients with head and neck squamous cell carcinoma (HNSCC) treated with chemo radiotherapy.MethodsIn this 5-year prospective study, patients with recurrent head and neck squamous cell carcinomas (HN-SCC) after primary treatment with chemoradiotherapy or radiotherapy that candidate for surgery were enrolled. In total, 50 patients with squamous cell carcinomas of the head and neck with N0 neck were included in the study. Age, initial location of recurrent tumor, T staging in primary and recurrent tumors, neck condition (N0 or N+), and pathology report for neck metastasis, number of affected lymph nodes and duration of tumor recurrence were examined.ResultsOut of 50 patients with mean age of 57.04 ± 14.4 years, 13 were female (26%) and 37 (74%) were male. In terms of primary tumor size, 52% (26 patients) were in T2 stage. The primary and recurrent tumor was located in the oral cavity in 33 patients (66%). Nine 0f 50 patients (18%) had occult metastases.ConclusionIt seems that END surgery is necessary for treatment the occult lymph node neck metastasis of recurrent head and neck cancers with N0 neck. Therefore, it is possible that END surgery has reduced cervical recurrence in these patients.     

The role of human papillomaviruses (HPV) in upper respiratory tract diseases

High-risk papillomaviruses (HPVs) are etiologic agents for anogenital tract cancers and have been detected in head and neck squamous cell carcinomas. Still a viral etiology of head and neck cancers had not been established unambiguously. For head and neck cancers two major risk factors (tobacco smoke and alcohol) have been recognised and HPV infection may play a synergistic role in the multifactorial etiology of the tumors. The occurrence rates for HPV DNA in the head and neck cancers varied from one study to another because of technical and demographic variables. The HPV infection in benign head and neck diseases were also presented.     

Role of human papillomavirus in the development of head and neck squamous cell carcinomas

Objective To review the literature on the role of oncogenic human papillomaviruses (HPVs) in the carcinogenesis of the head and neck mucosa.

Material and Methods Molecular and epidemiological studies concerning the high-risk HPV types and their role in carcinogenesis in the head and neck region were screened.

Results Different studies revealed that: (i) 15–25% of head and neck squamous cell carcinomas (HNSCCs) are clonally associated with high risk HPV types (type 16); (ii) the oropharynx and particularly the tonsils are the most susceptible sites; (iii) patients with HPV-positive tumours present with more advanced stages of disease, are relatively younger, do not have extravagant tobacco and alcohol intake and seem to have a better survival; (iv) HPV-positive tumours are characterized by poor differentiation grade and a basaloid appearance; and (v) HPV-positive tumours exhibit integrated HPV DNA, wild-type p53, pRb downregulation and overexpression of p16^INK4A.

Conclusion Taken together, these data support the view that HPV-harbouring HNSCC can be considered a discrete tumour entity with, moreover, a favourable prognosis. Screening of patients, especially those with tonsillar cancers, for the presence of HPV may help to further optimize treatment protocols and to provide more accurate prognostic information.     

Human papillomavirus infection and oral squamous cell carcinoma - a systematic review

IntroductionThe association between uterine cervix and anogenital carcinomas and human papillomavirus, HPV, is well established, however the involvement of this virus in the development of oral squamous cell carcinomas remains controversial.ObjectivesTo evaluate the relationship between HPV infection and oral squamous cell carcinomas, and to estimate the incidence of this infection in these patients.MethodsFour electronic databases were searched to find studies that met the following inclusion criteria: i) performed in humans; ii) were cohort, case-control or cross-sectional; iii) assessed the HPV oncogenic activity by the E6 and E7 mRNA; iv) included primary oral squamous cell carcinomas which; v) diagnosis had been confirmed by biopsy. Information about the country; study period; sample obtainment; sites of oral squamous cell carcinomas; number, gender and age range of the population; the prevalence of HPV infection and subtypes detected; use of tobacco or alcohol and oral sex practice were extracted. The methodological quality of included articles was assessed using 14 criteria.ResultsThe search strategy retrieved 2129 articles. Assessment of the full text was done for 626 articles, but five were included. The total of participants included was 383, most of them male with mean age between 51.0 and 63.5 years old. Seventeen patients were HPV/mRNA-positive, being the subtypes 16 and 18 detected more frequently. Nine of the HPV/mRNA-positive oral squamous cell carcinomas occurred on the tongue. The quality score average of included articles was five points.ConclusionsAmong the 383 oral squamous cell carcinoma patients included, 17 (4.4%) were HPV/mRNA-positive, nevertheless it was not possible to assess if HPV infection was associated with oral squamous cell carcinomas because none of the studies included was longitudinal and cross-sectional investigations do not have control group.     

Cell kinetic markers in cutaneous squamous and basal cell carcinoma of the head and neck

IntroductionProliferation markers play a significant role in the biologic behavior of tumors. Geminin is a known inhibitor of the cell cycle and DNA replication and has not been previously reported in cutaneous basal and squamous cell carcinomas of the head and neck.ObjectivesWe aimed to investigate proliferation markers ki67, MCM2, and geminin in head and neck cutaneous basal and squamous cell carcinomas.MethodsForty cases of each tumor were immuostained with ki67, MCM2, and geminin followed by assessment of labeling indices (LIs). MCM2/ki67- and geminin/ki67-ratios were also determined; t-test was used for statistical analysis (p < 0.05).ResultsThere was no significant difference in ki67 (p = 0.06) and MCM2 (p = 0.46) between cutaneous basal and squamous cell carcinomas; however, geminin LI was significantly higher in squamous cell carcinomas compared to cutaneous basal cell carcinomas (p < 0.001). Only geminin/ki67 showed a significant difference between the two tumors with the ratio showing significantly higher numbers in squamous cell carcinomas (p = 0.015).ConclusionsGeminin could be regarded as an effective factor in the pathogenesis of head and neck cutaneous cutaneous basal cell carcinomas and squamous cell carcinomas and may be one of the responsible elements in the difference between the biologic behavior of these tumors.     

Type 6/11 and 16/18 squamous epithelial cancers of the upper respiratory tract and digestive system. An in situ hybridization study]

61 squamous cell cancers (27 laryngeal, 12 hypopharyngeal, 14 tonsillary, 8 tongue) with different keratinization and grading and seven lymph node metastases of HPV 16/18 positive carcinomas were analysed for the presence of HPV-DNA by in situ hybridisation. 65.5% of them were found to be positive. Twelve laryngeal carcinomas (44%), five tonsillary tumours (35.7%), eight tumours of the hypopharynx (66.6%) and three tongue carcinomas (37.5%) were shown to contain HPV 16/18 DNA. The detection rates of HPV 6/11 were lower. 44 of the analysed tumours (72.1%) had a grading G2. 29 of these tumours (65.9%) were HPV positive. Only eight of the patients were no heavy smokers or alcoholic drinkers. One of the lymph node metastases was positive for HPV 16/18. The results indicate that HPV may be involved in the pathogenesis of squamous cell carcinomas of head and neck tumours.     

Possible implication of Mdm2 as a prognostic marker in invasive laryngeal carcinoma

Laryngeal squamous cell carcinoma is one of the most common malignant neoplasms of the head and neck. In Brazil, laryngeal tumors represent 2% of all cancers and are associated with approximately 3,000 deaths annually. Human papillomavirus (HPV) has been reported to play an important role in the etiology of laryngeal cancer. The aim of the present study was to evaluate the expression of p53, p27, and Mdm2 in laryngeal carcinomas. Sixty-three larynx biopsies were selected for the study, including 9 in situ laryngeal carcinomas, 27 laryngeal carcinomas without metastasis and 27 laryngeal carcinomas with metastasis. Twenty-seven cervical lymph nodes from patients with metastatic lesions were also evaluated. The expression levels of p53, p27, and Mdm2 were assessed by immunohistochemistry using a computer-assisted system. HPV detection and typing were performed using PCR, and the HPV types that were evaluated included HPV 6, 11, 16, 18, 31 and 33. Out of 63 patients, 53 (84.1%) were positive for β-globin (internal control), and 10 (15.9%) were β-globin negative and therefore excluded from the evaluation. Thus, 7 (13.2%) out of 53 patients were HPV positive, and 46 (86.8%) out of 53 patients were HPV negative. Statistically significant differences (p?<?0.05) in Mdm2 expression levels were observed in the in situ laryngeal carcinoma samples compared with the laryngeal carcinoma samples with metastasis. No statistically significant differences (p?>?0.05) in either p53 or p27 expression levels were detected. These findings suggest that Mdm2 may be associated with the invasiveness and aggressiveness of laryngeal carcinomas.     

Assessment of HPV 16, HPV 18, p16 expression in advanced stage laryngeal cancer patients and prognostic significance

IntroductionHuman papilloma virus is an etiological risk factor for a subset of head and neck squamous cell carcinomas. HPV has been proven to be a powerful prognostic biomarker for oropharyngeal cancer, but its role in the larynx has not been explored in depth. The developmental mechanisms of laryngeal carcinomas are quite complex and controlled by various factors. Smoking and alcohol are most important risk factors. Recent studies indicate that HPV infection also plays an important role in larynx carcinomas. HPV related laryngeal carcinomas especially occur at the supraglottic region of larynx.ObjectiveWe aimed to determine the frequency of HPV/protein16 positivity in patients with laryngeal carcinoma and association of HPV and/or p16 positivity with variables such as age, sex, smoking habits, tumor localization, lymph node metastasis, recurrence and survival in advanced stage laryngeal carcinoma in our study.MethodsThis retrospective study included 90 patients with advanced laryngeal carcinoma. The Control group was 10 normal larynx mucosa specimens. The presence of HPV was investigated polyclonally by polymerase chain reaction, and protein16 with immunohistochemical method. In HPV positive cases, the presence of HPV types 16, 18 were evaluated by polymerase chain reaction. Demographic features of patients were noted. Patient survival and association with HPV/protein16 was determined.ResultsPolyclonal HPV positivity was detected in 11 (12.2%) of 90 cases. Out of these 11 cases, HPV 16 was positive in 6, HPV 18 in 4, and both HPV 16 and 18 were positive in 1. In 18 (20%) of the cases, p16 was positive. Six of the cases (6.6%) had both HPV and protein16 positivity. In cases where protein16 alone or HPV and protein16 were co-positive, alcohol use was less and the tumor was found more likely to be localized in the supraglottic area. These ratios were statistically significant. Supraglottic localization of tumor was determined to be increased in protein16 positive cases. The correlation between protein16 positivity and supraglottic area location was determined to be statistically significant (p = 0.011). 55.6% of protein16 positive cases was located in the supraglottic region, 33.3% was glottic and 11.1% was transglottic. Although life expectancy over 5 years were numerically higher in HPV and protein16 positive cases, this was not found to be statistically significant. There was no statistically significant relationship between HPV positivity and mean age, differentiation, smoking and alcohol use, tumor progression, lymph node metastasis, localization, recurrence, cause of mortality and treatment methods in our study. The mean follow-up period of our patients was 6.7 years.ConclusionThe close relationship between HPV and oropharyngeal squamous cell carcinoma could not be shown in larynx malignancy in many studies, including our study. Our findings support a limited role of HPV in laryngeal carcinogenesis. Protein16 is not a reliable surrogate for HPV status in laryngeal cancers and is not a predictor of laryngeal cancer survival. Supraglottic localization of tumor was determined to be increased in protein16 positive cases. The correlation between protein16 positivity and supraglottic area location was determined to be statistically significant. There is a need for more populated clinical trials, where neoplastic proliferation is better demonstrated and the accuracy of the results obtained is supported by different techniques.     

Human papillomavirus co-infection and survival in oral and oropharyngeal squamous cell carcinoma: A study in 235 Brazilian patients

ObjectivesWhile unknown for oropharyngeal squamous cell carcinoma (OPSCC) and oral squamous cell carcinoma (OSCC), some studies assessing cervical carcinoma have shown that human papillomavirus (HPV) co-infection can be associated with its prognosis.MethodsThrough in situ hybridization (HPV and Epstein-Barr virus [EBV] probes) and immunohistochemistry (p16^INK4a, cyclin D1, p53, and Ki-67 antibodies), 126 OPSCC and 109 OSCC samples were assessed.ResultsAll patients were EBV-negative. OPSCC (25%) showed a significant association with HPV compared to OSCC (11%). Almost all HPV-associated cases were p16^INK4a-positive. Regarding OPSCC and OSCC, 23 and 7 cases were positive for high-risk HPV (HRHPV) only, 6 and 3 cases for low-risk HPV (LRHPV) only, and 3 and 2 cases for HRHPV/LRHPV, respectively. HPV-associated carcinomas showed a significantly higher proliferative index than HPV-unassociated carcinomas. Both carcinomas showed a similar overall survival rate, which was not affected by the HPV status. However, when comparing HPV-associated subgroups, patients with HRHPV/LRHPV-associated carcinomas showed worse survival.ConclusionLRHPV-associated and HRHPV/LRHPV-associated cases can also be detected when assessing OSCC and OPSCC. Further studies, especially in populations with a high prevalence of HPV-associated OPSCC, are necessary to understand the clinicopathological behavior of these neoplasm subgroups.     

Role of human papillomavirus in the development of head and neck squamous cell carcinomas

OBJECTIVE: To review the literature on the role of oncogenic human papillomaviruses (HPVs) in the carcinogenesis of the head and neck mucosa. MATERIAL AND METHODS: Molecular and epidemiological studies concerning the high-risk HPV types and their role in carcinogenesis in the head and neck region were screened. RESULTS: Different studies revealed that: (i) 15-25% of head and neck squamous cell carcinomas (HNSCCs) are clonally associated with high risk HPV types (type 16); (ii) the oropharynx and particularly the tonsils are the most susceptible sites; (iii) patients with HPV-positive tumours present with more advanced stages of disease, are relatively younger, do not have extravagant tobacco and alcohol intake and seem to have a better survival; (iv) HPV-positive tumours are characterized by poor differentiation grade and a basaloid appearance; and (v) HPV-positive tumours exhibit integrated HPV DNA, wild-type p53, pRb downregulation and overexpression of p16INK4A. CONCLUSION: Taken together, these data support the view that HPV-harbouring HNSCC can be considered a discrete tumour entity with, moreover, a favourable prognosis. Screening of patients, especially those with tonsillar cancers, for the presence of HPV may help to further optimize treatment protocols and to provide more accurate prognostic information.     

头颈部鳞癌颈淋巴结隐匿性转移

目的 探讨头颈部鳞癌隐匿性颈淋巴结转移的特点和规律。方法 对111例头颈部鳞癌N_0M_0患者的颈淋巴结清扫标本进行切片观察。结果 隐匿性转移总体发生率为26.12％(29/111)。其中口腔癌18.75％(15/80),口咽癌25.00％(1/4),下咽癌54.54％(6/11),喉癌43.75％(7/16)。原发癌临床分期、肿瘤细胞分化程度是影响颈淋巴结隐匿性转移的重要因素。111例N_0M_0患者5年生存率为66.7％,其中pN~-为74.39％(61/82),pN~ 为44.82％(13/29)。结论 对临床T_3和T_4期、癌组织分化程度低和深度浸润的cN_0头颈部鳞癌应行选择性颈清扫术以治疗颈淋巴结隐匿性转移并提高患者的生存率。     

Presenting symptoms and clinical findings in HPV-positive and HPV-negative oropharyngeal cancer patients

Objectives: Oropharyngeal squamous cell carcinoma (OPSCC) is divided in two different disease entities depending on HPV involvement. We investigated differences in presenting symptoms and clinical findings in patients with HPV-positive and -negative OPSCC tumors.

Methods: Altogether 118 consecutive patients diagnosed with primary OPSCC between 2012 and 2014 at the Helsinki University Hospital were included. HPV-status of the tumors was assessed by PCR detection of HPV DNA and immunostaining with p16-INK4a antibody.

Results: Fifty-one (47.7%) of the patients had HPV-positive and 56 (52.3%) HPV-negative tumors. Forty-nine (49/51, 96.1%) of the HPV+ tumors were also p16+ showing high concordance. The most common presenting symptom among HPV+/p16+ patients was a neck mass (53.1%), whereas any sort of pain in the head and neck area was more frequently related to the HPV?/p16? (60.0%) group. HPV+/p16+ tumors had a tendency to locate in the tonsillar complex and more likely had already spread into regional lymph nodes compared with HPV?/p16? tumors. Smoking and heavy alcohol consumption were significantly more common among HPV?/p16? patients but also rather common among HPV+/p16+ patients.

Conclusions: This analysis of symptoms and signs confirm that OPSCC can be dichotomized in two distinct disease entities as defined by HPV status.     

Interpretation of suspect head and neck fixations seen on PET/CT in lung cancer

ObjectivesSmoking is the major risk factor for lung and head and neck cancer. The purpose of the present study was to determine the clinical impact of serendipitously revealed head and neck fixation on PET/CT in patients undergoing investigation for lung cancer.Material and methodsThe reports from PET/CT studies for patients with lung cancer from September 2005 and April 2012 were retrospectively reviewed. Head and neck incidentaloma was interpreted as suggestive of second primary malignancy. These incidental findings were compared with the final diagnosis obtained from clinical and histological investigation.ResultsFive hundred and ninety-two patients were investigated on PET/CT for lung cancer in the study period. PET/CT-positive head and neck lesions suggestive of second primary malignancy were found in 65 (11%) patients. Nasoendoscopy was performed in 23 patients and biopsy in 10. In 4 patients (17.4% of those explored), a second primary malignant lesion was proved on histology: 2 squamous cell carcinomas (larynx and oral cavity), 1 undifferentiated carcinoma (parotid), and 1 osteosarcoma (mandible). At a median 13 months’ follow-up, 3 of the 4 patients with a second primary had died from disease-related causes and 1 was free of recurrence. Metastases from lung adenocarcinoma were found in 2 patients (0.34%).ConclusionsPET/CT detected incidental head and neck malignant tumors in at least 0.68% of lung cancer patients, but in 6.4% of those with suspect head and neck fixation.     

Detection of human papillomavirus in clinical samples

The confirmation of human papillomavirus (HPV) as a causative agent for a subset of squamous cell carcinomas of the head and neck has resulted in a growing expectation for HPV testing in head and neck cancers. An increasing understanding of HPV-related tumorigenesis has informed this evaluation process in a manner that is moving wide scale, indiscriminant, and nonstandardized testing toward a more directed, clinically relevant, and standardized approach. This review addresses the current state of HPV detection and focuses on the importance, appropriate time, and need for HPV testing.     

Expression of cyclin-dependent kinase inhibitor 2A 16, tumour protein 53 and epidermal growth factor receptor in salivary gland carcinomas is not associated with oncogenic virus infection

It is known that human papillomavirus (HPV) infection can cause squamous cell neoplasms at several sites, such as cervix uteri carcinoma and oral squamous carcinoma. There is little information on the expression of HPV and its predictive markers in tumours of the major and minor salivary glands of the head and neck. We therefore assessed oral salivary gland neoplasms to identify associations between HPV and infection-related epidermal growth factor receptor (EGFR), cyclin-dependent kinase inhibitor 2A (CDKN2A/p16) and tumour protein p53 (TP53). Formalin-fixed, paraffin-embedded tissue samples from oral salivary gland carcinomas (n=51) and benign tumours (n=26) were analysed by polymerase chain reaction (PCR) analysis for several HPV species, including high-risk types 16 and 18. Evaluation of EGFR, CDKN2A, TP53 and cytomegalovirus (CMV) was performed by immunohistochemistry. Epstein–Barr virus (EBV) was evaluated by EBV-encoded RNA in situ hybridisation. We demonstrated that salivary gland tumours are not associated with HPV infection. The expression of EGFR, CDKN2A and TP53 may be associated with tumour pathology but is not induced by HPV. CMV and EBV were not detectable. In contrast to oral squamous cell carcinomas, HPV, CMV and EBV infections are not associated with malignant or benign neoplastic lesions of the salivary glands.     

Genotypic analysis of tumor suppressor genes PTEN/MMAC1 and p53 in head and neck squamous cell carcinomas

Objectives: Tumor suppressor gene mutations in both p53 and PTEN/MMAC1 genomic DNA have been detected in many types of cancer. The purpose of this study was to investigate the presence and importance of PTEN/MMAC1 mutations in squamous cell carcinomas. Methods: Exons of each gene were amplified after polymerase chain reaction (PCR) using genomic DNA derived from cell lines of squamous cell carcinoma of the head and neck (SCCHN) and snap-frozen biopsy specimens from primary established head and neck tumors. The amplified and purified DNA was then sequenced directly. Result: As anticipated, point mutations of the p53 gene were found in 80% of cell lines examined. A single base mutation in codon 151 was found in six of 10 cell lines studied. PTEN/MMAC1 gene mutations were found in neither the cell lines tested nor the tumor biopsy samples. Conclusion: This study, as well as a large volume of data, confirms that mutations of the p53 gene are frequent events in head and neck cancer cell lines. Although PTEN/MMAC1 gene mutations have been found in a variety of carcinomas, this gene was not found to be mutated in SCCHN cell lines or in primary squamous cell carcinomas of the head and neck. This information is useful for further studies of mutations in these cell lines. Laryngoscope, 108:1553–1556, 1998