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

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

头颈部肿瘤组织中PD-L1的表达及临床意义分析

目的 探讨头颈部肿瘤组织中细胞程序性死亡配体-1（PD-L1）的表达情况及临床意义。方法 将2015 年1 月至2016年6月收治的40例头颈部恶性肿瘤组织及20例头颈部囊肿组织的手术标本经包埋制作成蜡块,采用免疫组织化学SP二步法检测以上组织中的PD-L1蛋白表达情况,分析PD-L1表达水平与临床病理参数（年龄、性别、病理分化程度和临床分期）的关系。结果PD-L1在头颈部囊肿组织中不表达,头颈部肿瘤组织中的阳性表达率为65.0%（26/40）,高于头颈部囊肿组织,差异有统计学意义（P<0.05）。PD-L1表达与年龄、性别及病理分化程度无关（P>0.05）,而与患者的临床分期有关（P<0.05）。结论 PD-L1在头颈部恶性肿瘤组织中表达升高,可为头颈部恶性肿瘤的免疫靶向治疗提供参考。     

Detection of circulating tumor cells and of tumor DNA in plasma during tumor progression in rats

The role and clinical significance of circulating tumor cells and of tumor DNA in the plasma have not yet been clarified. In the present study, we compared rates of detection of tumor-derived DNA in the buffy coat to those in plasma from tumor-bearing rats, and we attempted to correlate these rates with the progression of tumors. We injected DHD/K12-PROb cancer cells subcutaneously into BD-IX rats and divided the animals into six groups according to the time between the injection of tumor cells and euthanasia. After euthanasia, macroscopic metastases were assessed and samples of blood and lung were collected. We used mutant allele-specific amplification by PCR to detect tumor-derived DNA. We detected tumor DNA in lung samples from the first week after inoculation, in plasma from the third week and in the buffy coat from the fifth week. All animals analyzed on the 11th week had macro- or micrometastases in their lungs. Regardless of group, the rate of PCR-positive plasma samples was significantly higher than that of circulating tumor cells (P=0.005). In animals with metastases, this difference was also statistically significant (P=0.008). However, neither the detection of tumor DNA in the plasma nor the presence of circulating tumor cells was strongly correlated with the presence of metastases. Thus, cell-free tumor DNA was detected sooner and more frequently than circulating tumor cells and the dissemination of tumor DNA in the plasma seems to be much more common than detectable hematogenic tumor cells during the spread of colorectal cancer.     

Circulating tumor-derived mutant mitochondrial DNA: a predictive biomarker of clinical prognosis in human squamous cell carcinoma

While circulating tumor-derived molecules have been identified in a variety of malignant tumors, it is sometimes difficult to detect the molecular targets due to the lower serum concentration. We report that evaluation of circulating tumor-derived mitochondrial DNA (mtDNA) seems to have novel efficiency for detecting tumoral micrometastasis. In murine xenografting human oral cancer cells, human mtDNAs could be quantitatively detected from multiple organs and blood samples whereas human nucleic DNAs could not. We also determined if this mtDNA blood test was relevant for patients with oral cancer with no histologic evidence of tumoral cells in their surgical margins. For this, mtDNA from normal and tumorous tissues and serum mtDNA obtained pre and postoperatively was examined at three different regions including the displacement loop, 12S-rRNA, and 16S-rRNA. All non-recurring patients had significantly higher amounts of mutant mtDNAs in the tumoral tissues compared with the non-recurring group. More importantly, on the blood test with the cut-off point by receiver operating characteristic (ROC) curve analysis, while the vast majority of serum mtDNA samples obtained postoperatively in the recurring cases maintained significantly higher amounts of mutant mtDNAs, the non-recurring cases did not, and they showed good prognosis. This is the first report of this approach for managing patients after resection of oral tumors, and may have substantial diagnostic potential for other tumoral types.     

Detection of plasma tumor DNA in head and neck squamous cell carcinoma by microsatellite typing and p53 mutation analysis

Recent arguments have suggested that tumor DNA in cancer patients could be found in plasma, but different points remain unclear. Using a series of 117 head and neck squamous cell carcinoma tumors, our goals for this study were: (a) to quantify the amount of plasma DNA; (b) to evaluate the presence of plasma tumor DNA; and (c) to analyze the clinical relevance of tests based on plasma DNA analyses. Low levels of plasma DNA were found in most samples, but all were successfully amplified. Two different methods were used to detect tumor-specific genetic alterations: (a) microsatellite instability at UT5085 with an established sensitivity of 1:500; and (b) p53 mutation screening. Of the 117 tumors typed at UT5085, 65 demonstrated bandshifts (55%). Plasma and tumor DNA a showed similar alteration in only one case among these samples, and the prevalence of tumor DNA in plasma was estimated to be <2% using microsatellite analysis. Tumor DNA was detected in plasma at a higher prevalence (2 of 11 cases) when using p53 mutant allele-specific amplification. These results showed that in plasma, tumor DNA is largely diluted by normal DNA. By comparison with previously published studies, the prevalence of microsatellite alterations in plasma in this series of head and neck squamous cell carcinomas is very low, despite the fact that a large series of tumors was analyzed. To explain this discrepancy, we analyzed the possibility of PCR artifacts as suspected by the presence of loss of heterozygosity in two plasma DNA samples without a similar tumor DNA alteration. When DNA concentrations were under the threshold of detection (<100 ng/ml), we demonstrated that PCR artifacts could occur at random, and, if misinterpreted, these false genetic alterations could artificially enhance the frequency of plasma DNA alterations. This may have been suspected in previously published series, but it has never been discussed before. Microsatellite analysis on plasma DNA is difficult to interpret and can frequently be misleading. Plasma DNA should be analyzed with very sensitive and specific methods such as mutant allele-specific amplification, which excludes artifacts but requires specific optimization that is probably not compatible with routine and clinical use.     

Detection of High-Risk Human Papillomavirus Genotypes 16 and 18 in Head and Neck Squamous Cell Carcinomas in Jordan

Background: Recently, associations of the human papillomavirus (HPV) with head and neck cancer have become well established. Of particular concern, the severity and pathological outcomes of squamous cell carcinomas are remarkably affected by the genotypes of HPV present in such lesions. This study was conducted to investigate the occurrence of HPV genotypes, particularly high risk 16 and 18, among oral and laryngeal squamous cell carcinomas in Jordan. Methods: During the period of May 2015 to March 2016, we evaluated a total of 108 paraffin-embedded tissue samples, histologically confirmed as SCC, of both oral and laryngeal tumors for the presence of HPV DNA. DNA was extracted using a Zymogen commercial kit. HPV genotypes were detected by nested PCR using consensus primers followed by primer-specific PCR for HPV-16 and HPV-18 genotypes. The genotypes were confirmed by DNA sequencing methods. Results: Sixteen samples were positive for HPV DNA (14.8%) with higher rates in oral tumors compared to their laryngeal counterparts (20% and 6% respectively). The HPV-16 genotype predominated, being detected in 81.3% of the cases as a single infection and in 18.7% in combination with HPV-18. A significant association between the anatomical location and the HPV-16 genotype was observed (p < 0.05). In contrast, no significant associations could be established with tumor grade and gender or age. Conclusions: A relatively high rate of high-risk HPV genotypes, especially HPV 16, is evident in head and neck cancers SCCs in Jordan. Genotyping of HPV might be of considerable value for evaluation of progression.     

Real-time quantitative PCR demonstrates low prevalence of human papillomavirus type 16 in premalignant and malignant lesions of the oral cavity.

PURPOSE: Human papillomavirus (HPV) type-16 has been associated with invasive squamous cell carcinoma of the head and neck. This study examines the role of HPV-16 in the progression of oral head and neck cancer by determining the quantity of HPV-16 DNA in premalignant and malignant lesions, using real-time quantitative PCR, to more accurately determine the role of HPV-16 in oral head and neck squamous cell carcinogenesis. EXPERIMENTAL DESIGN: We examined 102 microdissected premalignant head and neck lesions (85 from the oral cavity), 34 invasive oral cavity squamous cell carcinomas, as well as 18 invasive tumors known to be HPV positive by traditional molecular technology for the presence of HPV-16 DNA using real-time quantitative PCR. RESULTS: HPV DNA was detected in 1 of 102 premalignant lesions (0.98%), 1 of 34 (2.9%) invasive oral cavity carcinomas, and 14 of 18 (78%) known HPV-positive tumors. CONCLUSIONS: HPV-16 infection and integration is seldom found in oral premalignant lesions and invasive carcinoma, and therefore rarely contributes to malignant progression in the oral cavity. Furthermore, quantitative PCR is a useful technique that reliably excludes contaminated samples and those with minimal HPV DNA content that is unlikely to be significant in carcinogenesis.     

Quantitative analysis of cell-free Epstein-Barr virus DNA in plasma of patients with nonnasopharyngeal head and neck carcinomas.

PURPOSE: We investigated the detectability of EBV DNA in the plasma of patients with non-nasopharyngeal head and neck carcinomas (NNHNC). Previous studies have shown that EBV is present in the tumor tissue of some NNHNC. EXPERIMENTAL DESIGN: We recruited 101 patients with NNHNC and 48 healthy controls. Blood samples were taken from controls and patients before treatment. Tumor tissue samples were tested for the presence of EBV in the first 69 patients by in situ hybridization for small EBV-encoded RNA (EBER). Plasma EBV DNA was measured by real-time quantitative PCR in patients and controls. RESULTS: Squamous cell carcinoma (SCC) was the commonest histology (78 patients) followed by lymphoepithelial carcinoma (8 patients). EBER was detected in tumor cells in 7 of 69 patients tested. All of the EBER-positive tumors were lymphoepithelial carcinoma. Two controls (2 of 48; 4.2%) had detectable plasma EBV DNA. Plasma EBV DNA was detected in all of the patients with EBER-positive tumors, and in 23 of 94 (24.5%) patients with tumors of EBER-negative or unknown status. The proportion of plasma EBV DNA-positive cases in either group was significantly higher than that in the control group (P < 0.0027). Plasma EBV DNA concentrations in patients with EBER-positive tumors (median, 3827 copies/ml) were significantly higher than those in the controls (median, 0 copy/ml; P = 0.0001). Of patients with SCC, 21 (26.9%) had detectable plasma EBV DNA (median concentration, 34 copies/ml). Plasma EBV DNA concentrations in the whole group of patients with SCC (median, 0 copy/ml; interquartile range, 0-4 copies/ml) were also significantly higher than those in the controls (P = 0.001). CONCLUSIONS: Our data indicate that plasma EBV DNA reflects tumoral EBER status, and it may be of use as a tumor marker for EBER-positive NNHNC. The biological and clinical significance of low levels of circulating EBV DNA in the minority of patients with EBER-negative tumors remain to be elucidated.     

Human papillomavirus type 16 and squamous cell carcinoma of the head and neck.

PURPOSE: Human papillomavirus (HPV) has previously been reported to be associated with squamous cell carcinoma of the head and neck. Our objective was to investigate the presence and type of HPV infection in head and neck tumors and determine whether infection was associated with individual tumor characteristics, patients' pattern of tobacco and alcohol exposure, or with clinical outcome. Experimental Design: Using a case series design, fresh tumor samples were obtained from a series of 89 head and neck squamous cell carcinoma patients, including 64 men and 25 women. The majority of tumors were located in the oral cavity, followed by the oropharynx. A PCR-based technique with restriction fragment length polymorphism analysis was used to detect and type HPV. RESULTS: Of the 89 patients, 18 (20%) had detectable HPV 16 in their tumor samples. HPV 16 was detected in 64% of tonsil tumors, 52% oropharyngeal tumors, and 5% oral cavity tumors. The mean age of subjects with HPV 16-positive tumors was younger than the patients with HPV-negative tumors. Also, this group consumed less alcohol on a weekly basis and had a better clinical outcome compared with the HPV-negative group. Smoking, clinical stage, tumor grade, and tumor-node-metastasis status were not associated with HPV 16 presence. CONCLUSIONS: Our study supports the previous reports that suggest HPV 16 is associated with squamous cell cancers located in the oropharynx and oral cavity. The fact that HPV-positive tumors were observed in younger, lighter alcohol-consuming individuals with a better overall and disease-specific survival suggests a distinct disease process in these patients.     

A comparison of the clinical characteristics of first and second primary head and neck cancers. A population-based study

The clinical characteristics of 183 patients with second primary neoplasms in the head and neck region were compared with those of 20,598 patients with one primary tumor in the same region registered during the period 1973 to 1984 in the Surveillance, Epidemiology and End-Results Program. Second primary head and neck tumors were more likely to be diagnosed in a localized stage (47%) than if diagnosed as a single primary tumor (43%), but this difference was not significant. The tumor grade distribution was comparable in both groups. Using Cox proportional hazards modeling with age, sex, race, and stage as covariates, the median survival of patients with first and second head and neck cancer was identical (50 months). The survival of patients with localized second head and neck cancer was shorter than that of patients with single localized tumors (55 versus 102 months, P less than 0.026). Survival for regional tumors was similar (18 versus 21 months, not significant). The 84 second head and neck cancers in which the first head and neck cancer received radiation therapy (RT) had a median survival of 20 months; the 98 cases without prior RT had a median survival of 35 months. The high incidence of localized second cancers was probably due to the more intense surveillance. The worse survival in this group may be a result of prior RT or biologic characteristics of the tumor.     

Induction of apoptosis in head and neck tumor-cell lines by anti-fas antibody

Programmed cell death, currently termed apoptosis plays a key role in the maintenance of the steady state in continuously renewing tissues. Since little is known of apoptosis in head and neck tumors, we studied morphological changes in head and neck tumor-derived cell lines (KB, KBrc, HSC-2,3,4), induced by anti-Fas antibody. Light and electron microscopic examinations were carried out after culturing these cell lines with the antibody for 1-2 days. The antitumor effect of anti-Fas antibody on tumor cells differed with the cell lines. Most of the cell lines that were sensitive to anti-Pas antibody showed evidence of enhanced apoptosis when the cells were pretreated with interferon-gamma. The results suggest that the strategy of induction of apoptosis by anti-Fas antibody may be considered in treatment of some tumors of head and neck.     

Promoter hypermethylation patterns of p16, O6-methylguanine-DNA-methyltransferase, and death-associated protein kinase in tumors and saliva of head and neck cancer patients

Aberrant promoter hypermethylation is common in head and neck cancer and may be useful as a marker for cancer cells. We examined whether cells with tumor-specific aberrant DNA-methylation might be found in the saliva of affected patients. We tested 30 patients with primary head and neck tumors using methylation-specific PCR searching for promoter hypermethylation of the tumor suppressor gene p16 (CDKN2A), the DNA repair gene O6-methylguanine-DNA-methyltransferase (MGMT) and the putative metastasis suppressor gene death-associated protein kinase (DAP-K). Aberrant methylation of at least one of these genes was detected in 17 (56%) of 30 head and neck primary tumors; 14 (47%) of 30 at p16, 10 (33%) of 30 at Dap-K and 7 (23%) of 30 at MGMT. In 11 (65%) of 17 methylated primary tumors abnormal methylated DNA was detected in the matched saliva samples. Abnormal promoter methylation in saliva DNA was found in all tumor stages and more frequently in tumors located in the oral cavity. Moreover, none of the saliva from patients with methylation-negative tumors displayed methylation of any marker. Of 30 saliva samples from healthy control subjects (15 smokers and 15 nonsmokers), only one sample from a smoking patient was positive for DNA methylation at two target genes. Detection of aberrant promoter hypermethylation patterns of cancer-related genes in saliva of head and cancer patients is feasible and may be potentially useful for detecting and monitoring disease recurrence. Long-term longitudinal studies are needed to evaluate this approach for early detection of head and neck cancer in at-risk populations.     

A subset of head and neck squamous cell carcinomas exhibits integration of HPV 16/18 DNA and overexpression of p16INK4A and p53 in the absence of mutations in p53 exons 5-8

Besides well-known risk factors such as tobacco use and alcohol consumption, oncogenic human papillomavirus (HPV) infection also has recently been suggested to promote head and neck tumorigenesis. HPV is known to cause cancer by inactivation of cell cycle regulators p53 and pRb via expression of viral oncoproteins E6 and E7. This indicates that p53 mutations are not a prerequisite in HPV-induced tumor development. However, discrepancy exists with respect to the frequency of head and neck squamous cell carcinomas (HNSCC) harboring DNA of oncogenic HPV and the fraction of these tumors showing p53 mutations. In our study, we examined the frequency of HNSCC demonstrating HPV 16/18 integration as identified by fluorescence in situ hybridization (FISH) and investigated their p53 (mutation) status by immunohistochemistry and single-strand conformation polymorphism (SSCP) analysis of exons 5-8. Paraffin-embedded, archival biopsy material from 27 premalignant mucosal lesions and 47 cases of HNSCC were analyzed. Ten of the 47 (21%) HNSCC unequivocally exhibited HPV 16 integration, including 8 of 12 (67%) tonsillar carcinomas. This is supported by the immunohistochemical detection of p16(INK4A) overexpression in all 10 HPV-positive tumors. Although FISH is considered to be less sensitive than PCR-based methods for HPV detection, our data clearly demonstrate clonal association of HPV with these tumors, as illustrated by the presence of integrated HPV 16 in both the primary tumor and their metastases in 2 patients. In contrast, HPV 16/18 DNA could not be detected in the premalignant lesions. In 30 of 47 (64%), HNSCC accumulation of p53 was observed, including 8 of the 10 HPV-positive carcinomas. However, in none of the latter cases could mutations in exons 5-8 be identified, except for a polymorphism in codon 213 of exon 6 in one patient. Evaluation of clinical data revealed a significant inverse relation between tobacco use with or without alcohol consumption, and HPV positivity of the tumors.     

Specifics of diagnosis in primary-multiple synchronous tumors of the head and neck

The data of 100 case histories of primary-multiple synchronous malignancies of the head and neck have been analyzed. A second tumor was not detected during examination of the first one in every third case. The presence of tumor and pain were reported mostly by patients with neoplasms of the tongue, oral mucosa and, less frequently, laryngopharynx. In more than half the cases (48%), head and neck tumors were detected by physical examination. The most frequent were laryngeal tumors (30%), followed by those of the thyroid gland (26%). Second tumor incidence in the lung was (31%), breast (19%) and gastrointestinal tract (18%).     

循环DNA、循环肿瘤细胞端粒酶与肿瘤早期诊断

肿瘤患者循环DNA水平的增高、肿瘤特征性基因改变及循环肿瘤细胞端粒酶活性的表达,不仅可出现在肿瘤的晚期,也可发生在肿瘤的早期阶段。循环DNA和肿瘤细胞端粒酶的联合检测,对于肿瘤早期诊断有重要意义。     

Paragangliomas of the Head & Neck: the KMC experience

To determine the clinical features, investigations, intra-operative findings, surgical approaches used and the results of the treatment for paragangliomas of the head and neck. Retrospective study of 14 cases of paragangliomas in head and neck seen over a period of 10 years including five carotid body tumors, seven glomus jugulares and two glomus tympanicums. HRCT scans and bilateral carotid angiography were done in all cases of glomus jugulare. Pre-operative embolization was done in most cases. The trans-cervical approach was used for all cases of carotid body. In three cases of Type B jugulare tumors, a post-aural tympanotomy was used. A Fisch Type A approach was done for three cases of Type D jugulare tumors. Postaural tympanotomy approach was used for both patients with glomus tympanicum. In one case of extratympanic glomus jugulare tumor with hypoglossal palsy, a neck exploration was done to isolate and excise the tumor. Five patients with carotid body tumors presented as unilateral, painless, pulsatile swelling in the upper neck. Intra-operatively, three of the tumors were classified into Shamlin’s Grade II and one each into Grade III and Grade I. A carotid blow-out occurred in one of the patients with Grade II disease, which was managed. ECA resection had to be done in one case. Seven patients were diagnosed to have glomus jugulare and two with glomus tympanicum. Six glomus jugulare tumors presented with hearing loss, ear discharge and obvious swelling. Glomus tympanicums presented with hearing loss but no bleeding from the ear. On examination, tumors presented with an aural polyp with no VII nerve deficits. Both tympanicums were classified as Fisch Type A, three of the jugulares classified as Type B, two as Type D2 and one as Type D1. Tumors were found to be supplied predominantly by the ascending pharyngeal artery. In three cases of Type B jugulare tumors, a post-aural tympanotomy was used. A Fisch Type A approach was done for three cases of Type D jugulare. The transcanal approach was used for both patients with glomus tympanicum. Paragangliomas are uncommon tumors that need accurate diagnosis and skilled operative techniques. Though the surgical approaches may appear complicated, the removal provides good cure rates with minimal morbidity and recurrence. Lateral skull base approaches should be the armamentarium of every head and neck surgeon.     

Amplification of the int-2 gene in human head and neck squamous cell carcinomas

Head and neck squamous cell carcinomas (SCC) from 21 patients were analyzed for structurally rearranged or amplified proto-oncogenes by Southern blot hybridization. The int-2 proto-oncogene was amplified 3-5 fold in 5 (50%) of 10 laryngeal SCC and 2-3 fold in 5 (45%) of 11 nonlaryngeal SCC of the head and neck. Adjacent histologically normal tissue from the same patients had single int-2 gene copy number. Coamplification of int-2 and the epidermal growth factor receptor (c-erbB-1) gene was found in one laryngeal SCC and one SCC metastatic to the neck. No amplification or structural alterations of proto-oncogenes c-erbB-2/HER2, c-myc, H-ras-1, or K-ras-2 was detected in any of the head and neck tumors. In a survey of head and neck tumor-derived cell lines, int-2 was amplified 9 fold in a hypopharyngeal tumor cell line (FaDu), but not amplified in 3 laryngeal tumor cell lines. int-2 has been localized to the q13 band of chromosome 11. We used chromosome 11 specific probes to demonstrate that int-2 amplification was not due to complete or partial chromosome 11 duplication. int-2 amplification was localized to 11q13, but did not extend to the ets-1 locus 11q23. The results indicate that int-2 is frequently amplified in SCC of the head and neck and suggest that int-2 amplification may correlate with clinical disease progression.     

Molecular diagnosis of surgical margins and local recurrence in head and neck cancer patients: a prospective study.

PURPOSE: Approximately 10-30% of surgically treated head and neck cancer patients develop local recurrences while the resection margins are histologically tumor free. These recurrences may arise from cancer cells left behind but not detected by the pathologist, or they may develop from precursor lesions adjacent to the tumor that were not completely resected. We have investigated whether TP53-mutated DNA in the surgical margins is suitable to identify patients with head and neck squamous cell carcinoma at risk for local and locoregional recurrence. EXPERIMENTAL DESIGN: In a prospective cohort study of 76 patients with histologically tumor-free margins, the presence of TP53-mutated DNA was determined in the surgical margins using the phage plaque assay and correlated to clinical outcome. Immunostaining of the molecular-positive margins for mutated p53 protein was used to identify whether unresected precursor lesions or residual tumor cells were left behind. RESULTS: The absence of TP53-mutated DNA in surgical margins was significantly associated with remaining free of local and locoregional recurrence (P = 0.027 and P = 0.028, respectively). Moreover, the presence of TP53-mutated DNA in the surgical margins was an independent prognosticator for locoregional recurrence (relative risk = 7.1; P = 0.021; 95% confidence interval, 0.9-56). In 20% of the cases, the presence of TP53-mutated DNA in the surgical margins was found to be related to the presence of tumor-related precursor lesions. CONCLUSIONS: This study shows the value of TP53-mutated DNA as a molecular marker to predict locally recurrent head and neck squamous cell carcinoma. The observation that all patients who were negative for TP53-mutated DNA in the surgical margins remained free of local recurrence raises hope that molecular analysis of histologically tumor-free surgical margins can be exploited to decide on postoperative radiotherapy. Furthermore, our data provide evidence that local recurrences originate mainly from tumor cells left behind but also originate, in part, from unresected precursor lesions.