Tetranucleotide microsatellite instability in surgical margins for prediction of local recurrence of head and neck squamous cell carcinoma

A Prospective Study Between Molecular Marker P53 Analysis and HPE, for Tumour Positivity in Primary Resected Margins in Head and Neck Squamous Cell Carcinoma

Head and neck malignancies are the seventeenth most common malignancies, worldwide and second most common malignancy in India. So current study aims to compare between molecular marker p53 analysis and HPE for tumour positivity in primary resected margins in head and neck SCC. 61 patients with head and neck SCC were included in this prospective observational cross-sectional study performed in tertiary care hospital. A detailed history general physical examination blood investigation was done before the surgery. After the surgery, primary lesion from the resected tumour was sent for HPE analysis. From the same specimen, the margins at distance of 0.5-1 cm from primary tumour were sent for p53 mutation analysis. Report of p-53 mutation was noted and entered to the Performa. In our study we found out that in PDSCC HPE negative margins were found positive for p53 mutation in 81% cases. Which suggest that evaluation for p53 mutation should be done in PDSCC cases for HPE negative margins with in 1 cm. In patients of head and neck squamous cell carcinoma with free margins on HPE p-53 mutation is significantly associated to the PDSCC and margin upto 0.7 mm so recommended for p-53 profile can be beneficial in cases of the PDSCC and margins up to 0.7 mm for further management or for possibility of recurrence and its management to improve patients survival and decrease morbidity and mortality.

Fusobacterium nucleatum impairs DNA mismatch repair and stability in patients with squamous cell carcinoma of the head and neck

BACKGROUND

Dysbiosis of the laryngeal microbiota has been demonstrated to the development of head and neck squamous cell carcinoma (HNSCC), but the association of Fusobacterium and Fusobacterium nucleatum (F. nucleatum) with DNA mismatch repair (MMR) and microsatellite instability (MSI) has not been investigated.

METHODS

The abundance of Fusobacterium and F. nucleatum, the status of deficient MMR (dMMR) and MSI, and MMR-related gene expression were analyzed in 171 HNSCC tissues, 61 paired para-tumor tissues, and 60 vocal cord polyp tissues. The molecular mechanism of F. nucleatum and MMR-related gene expression were investigated in two human HNSCC cell lines (Tu 686 and FD-LSC-1).

RESULTS

Our results demonstrated that a high Fusobacterium abundance was detected in the HNSCC tissues and was exaggerated in the recurrent patients. We further found that a high Fusobacterium abundance was detected in the HNSCC tissues with dMMR and MSI. The Fusobacterium abundance was negatively correlated with the expression of MLH1, MSH2, and MSH6 in the HNSCC tissues. The Fusobacterium abundance was closely associated with the F. nucleatum abundance in the HNSCC tissues. F. nucleatum increased miR-205-5p expression to suppress MLH1, MSH2, and MSH6 expression via the TLR4- and MYD88-dependent innate immune signaling pathway, resulting in dMMR, DNA damage, and cell proliferation in HNSCC.

CONCLUSIONS

F. nucleatum impacts HNSCC epigenetic changes in tissues with dMMR to promote DNA damage and cell proliferation by suppressing MMR-related gene expression via the TLR4/MYD88/miR-205-5p signaling pathway, which is valuable in the development of efficient strategies for HNSCC prevention and treatment.

LAY SUMMARY

This study clearly indicates that Fusobacterium induced head and neck squamous cell carcinoma (HNSCC) aggressiveness to affect poor prognosis in HNSCC patients by epigenetic alteration of DNA mismatch repair (MMR) and microsatellite instability. Moreover, the research has shown that Fusobacterium nucleatum ( F. nucleatum ) impacts HNSCC epigenetic changes in tissues with deficient MMR to promote DNA damage and cell proliferation by suppressing MMRrelated gene expression via the TLR4/MYD88/miR-205-5p signaling pathway.

The Mismatch Repair System (MMR) in Head and Neck Carcinogenesis and Its Role in Modulating the Response to Immunotherapy: A Critical Review

Simple Summary

The dysfunction of the mismatch repair system, an important mechanism for the detection and correction of DNA replication mistakes, may often lead to instability in the length of specific genetic sequences, known as microsatellites, and to the accumulation of mutations. Microsatellite instability is a well-known risk factor for the development of colorectal cancers and other types of tumors but is also considered a positive predictor of the immunotherapy response. Malignancies harboring such a specific genomic instability are very immunogenic because of the great number of aberrant antigens they produce. Therapies based on the blockade of specific immune checkpoints have shown to induce an effective immune response against microsatellite-unstable cancer. Many studies proved that microsatellite instability has a decisive role in the carcinogenesis and the malignant progression of head and neck cancer and, in the near future, it may become a useful tool in tailoring immunotherapy also in this field of precision oncology.

Abstract

The mismatch repair (MMR) system has a major role in the detection and correction of DNA replication errors, resulting from DNA polymerase slippage or nucleotides misincorporation. Specific inherited/acquired alterations or epigenetic inactivation of MMR genes are associated with microsatellite instability (MSI): the loss of crucial function in repairing DNA alterations can promote carcinogenesis by favoring the accumulation of thousands of mutations in a broad spectrum of different anatomic sites such as colon, stomach, prostate, esophagus, endometrium, lung and head and neck. Recent extensive data suggest that tumor mutational burden strongly correlates with a clinical response to immunotherapy using checkpoint inhibitors and this response is influenced by MMR deficiency in a wide range of human solid cancers. In this context, few data about this crucial point are available for head and neck cancer (HNC). In this review, we discuss the role of MMR alterations and the resulting MSI in HNC pathogenesis. Furthermore, by summarizing the clinical available data on how they influence the progression of precancerous lesions and the risk of recurrence or second primary tumors, we want to define the current role of MSI in the management of HNC. Finally, we analyze the complex interaction between cancer cells and the immune system addressing the data now available about a potential correlation between microsatellite instability and immunotherapy response in HNC.

Emerging role of immune checkpoint inhibitors and predictive biomarkers in head and neck cancers

Head and neck cancers are a group of diverse and heterogeneous tumors, among which squamous cell carcinoma of the head and neck (SCCHN) is the most prevalent. Current treatment modalities have limited efficacy; therefore, new therapies are being actively developed and evaluated. The introduction of immune checkpoint inhibitors (ICIs) has led to a paradigm shift in the management of difficult-to-treat malignancies. In this review, we summarize recent advances in the development of immunotherapies, which are aimed at the functional restoration of the immune system to counteract immune-evasion strategies of cancer cells, and related biomarkers. Monotherapies with ICIs, which primarily target the programmed cell death-1 (PD-1) pathway, have shown promising results in clinical trials of patients with recurrent and metastatic SCCHN. Combinations of ICIs with conventional or virus therapies often have synergistic therapeutic effects, without increased toxicity. As only a small subset of patients respond to immunotherapy, biomarkers are essential for the prediction of treatment response and better selection of patients for ICIs. PD-1 ligand (PD-L1) expression is correlated with response but has several limitations as a predictive marker, as its expression is dynamic and heterogeneous, and the cut-off needs further confirmation. Therefore, tumor mutation burden, gene expression signatures, microsatellite instability, tumor-infiltrating lymphocytes, viral antigens, and the oral microbiota are being investigated as predictive biomarkers. Finally, we delineate other challenges and future prospects for improving patient outcomes, including the major challenge of identifying and validating predictive biomarkers that need to be addressed in future studies.

Molecular margins in head and neck cancer: Current techniques and future directions

Complete tumor extirpation with clear surgical margins remains a central tenet of oncologic head and neck surgery. Rates of locoregional recurrence and survival are both significantly worse when clear margins are unable to be obtained. Current clinical practice relies on the use of frozen sections intra-operatively, followed by traditional histopathologic analysis post-operatively to assess the surgical margin. However, with improved understanding of tumor biology and advances in technology, new techniques have emerged to analyze margins at a molecular level. Such molecular margin analysis interrogates tissue for genetic, epigenetic, or proteomic changes that may belie tumor presence or aggressive features not captured by standard histopathologic techniques. Intra-operatively, this information may be used to guide resection, while post-operatively, it may help to stratify patients for adjuvant treatment. In this review, we summarize the current state of molecular margin analysis and describe directions for future research.

EMAST frequency in colorectal cancer: a meta-analysis and literature review

Aim: The prognostic and predictive value of Elevated Microsatellite Alterations at Selected Tetranucleotide (EMAST) has been reported in colorectal cancer (CRC). The prevalence of EMAST in CRC varied across the literature. We conducted a meta-analysis to determine the prevalence of EMAST in CRC. Materials & methods: Three international databases including PubMed, ISI and Scopus were searched to identify related articles that described the frequency of EMAST. Results: Analysis was performed on 16 eligible studies including 4922 patients. The overall EMAST prevalence among CRCs patients was 33% (95% CI: 23-43%, I2 = 98%). Conclusion: This study indicated that approximately a third of the CRC patients are diagnosed with EMAST, hereupon EMAST as a prognostic and predictive biomarker should be more studied clinically.

MSI-L/EMAST is a predictive biomarker for metastasis in colorectal cancer patients

BACKGROUND

Microsatellite instability (MSI) is a prognostic marker in colorectal cancer (CRC). The biological significance of MSI-low (MSI-L) phenotype and its differences with microsatellite stable (MSS) phenotype remains unclear. The aim of this study is indicating the role of mononucleotide repeat in identifying MSI-L and revealing the association of MSI-L with elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) and oncologic outcome in CRC patients.

METHODS

MSI and EMAST status were analyzed using three quasimonomorphic panel (BAT-25, BAT-26, and NR-27) and five tetranucleotide repeats (D20S82, D20S85, D9S242, D8S321, and MYCL1), respectively, by capillary electrophoresis method without the need to fluorescent primers. The associations of MSI status with clinicopathological features, EMAST status, metastasis, and overall survival (OS) were investigated.

RESULTS

Among 159 CRC patient 22.0% were MSI-H, 40.3% were MSS, 37.7% were MSI-L, and 41.5% showed EMAST + phenotype. MSI-L were associated with advanced stages, EMAST⁺ tumors and worse OS ( p ≤ 0.001). Metastasis was relatively common in MSI-L/EMAST ⁺ CRCs and BAT-25 were the most unstable marker in these tumors.

CONCLUSIONS

MSI-L tumors have different clinicopathological features from MSS and MSI-H tumors. The MSI-L phenotype is a worse prognostic biomarker in CRC and when accompanied by EMAST could be a predictor for metastasis.

Genetic analysis of surgical margins in oral cavity cancer

BACKGROUND

A histological, tumour-free surgical margin does not guarantee recurrence-free survival in patients with cancer. This study investigated the association between microsatellite alteration in tumour-free surgical margins and local recurrence in patients with oral cavity squamous cell carcinoma.

METHODS

Patients with histologically confirmed oral cavity squamous cell carcinoma were enrolled in this prospective study. Cancerous specimens, corresponding surgical margins and peripheral blood were obtained. Microsatellite alteration was investigated using six dinucleotide microsatellite markers. All samples were amplified by PCR, followed by automatic fragment analysis.

RESULTS

Microsatellite alteration was identified in 100 specimens (69·0 per cent) from 145 patients. Among them, 85 specimens carried loss of heterozygosity, whereas 55 had microsatellite instability (MSI). Patients with MSI at the surgical margin had a higher risk of local recurrence on multivariable analysis (odds ratio 7·17, 95 per cent c.i. 3·49 to 14·73).

CONCLUSION

Molecular assessment of surgical margins can help identify patients at risk of local recurrence.

Oral verruciform xanthoma and erythroplakia associated with chronic graft-versus-host disease: a rare case report and review of the literature

BACKGROUND

Oral verruciform xanthoma is an uncommon benign lesion. Although oral verruciform xanthoma occurs in healthy individuals, it has been also reported in association with some inflammatory conditions. The aim of this study is to report a case of oral verruciform xanthoma associated with chronic graft-versus-host disease and to review the literature on this topic.

CASE PRESENTATION

A 47-year-old Caucasian male presented to the Sector of Oral Medicine "V. Margiotta", University Policlinic "P. Giaccone" of Palermo complaining of a mass on the gingiva. He first noticed the painless mass 1 year ago. He reported to have undergone allogenic hematopoietic stem cell transplantation 15 years ago for acute lymphoblastic leukaemia. Intraoral examination revealed a well-circumscribed, sessile yellowish and verrucous nodule upon canine, multiple yellowish and verrucous nodules on the hard palate, yellowish and verrucous nodules on left buccal mucosa. In addiction an area of white striae in a reticular pattern with erythema and ulceration was present on the dorsum of the tongue. This lesion was consistent with a known history of oral chronic graft versus host disease. Moreover, we observed a suspected area of oral erythroplakia yet on the dorsum of the tongue. In biopsy specimen of hard palate histopathological examination revealed a diagnosis of verrucous xanthoma of the oral cavity; in addiction in biopsy specimen of the dorsum of the tongue revealed the presence of erythroplakia with high grade dysplasia.

CONCLUSION

Verruciform xanthoma of the oral cavity associated with chronic graft-versus-host disease is a rare condition with a usually benign clinical course but malignant transformation has been described in association with oral potential malignant disorder (e.g. chronic graft versus host disease, erythroplakia). Very rare cases showed association with oral chronic graft versus-host-disease. To date, only eight cases were published in the world literature. Therefore it could be important follow up patients also for oral verruciform xanthoma onset.

Impact of microsatellite alteration in surgical margins on local recurrence in oral cavity cancer patients

The aim of this study was to investigate the association between microsatellite alteration in the surgical margins and local recurrence of oral cavity squamous cell carcinoma patients. Surgical specimens confirmed by pathological examination and corresponding surgical margins were collected from 120 oral cavity squamous cell carcinoma patients. Ten microsatellite markers were examined in the tumor specimens and paired surgical margins, which proved to be negative on pathological assessment. The specimens and surgical margins were amplified by polymerase chain reaction followed by computerized analysis. Forty-two specimens (35.0 %) with microsatellite instability (MSI) in at least one marker were found, and more than half of the specimens (n = 73, 60.8 %) had loss of heterozygosity (LOH) in at least one marker. Although MSI and LOH were not associated with the prognosis of oral cavity squamous cell carcinoma patients, presence of MSI in the tumor-free surgical margins increased the risk of local recurrence (hazard ratio: 9.549; 95 % confidence interval: 4.143-22.01). Genetic analysis of tumor-free surgical margins is a useful tool for identifying oral cavity squamous cell carcinoma patients who are vulnerable to local recurrence.

Microsatellite alteration in head and neck squamous cell carcinoma patients from a betel quid-prevalent region

We investigated the frequency of microsatellite alteration and their impact on survival in head and neck squamous cell carcinoma patients from an endemic betel quid chewing area. We collected 116 head and neck squamous cell carcinoma specimens along with corresponding surgical margins which were confirmed by pathological examination. Ten oligonucleotide markers were chosen for the assessment of microsatellite alteration. The specimens were amplified by polymerase chain reaction followed by automatic fragment analysis. There were 44 specimens (37.9%) with microsatellite instability (MSI) in at least one marker while more than half of the specimens (n = 68, 58.6%) had loss of heterozygosity (LOH) in at least one marker. Though MSI/LOH was not correlated with the survival of head and neck squamous cell carcinoma patients, presence of MSI in the tumor-free surgical margins was associated with local recurrence (odds ratio: 15.14; 95% confidence interval: 6.451 ~ 35.53; P < 0.001). Genomic assessment of surgical margin can help surgeons to identify head and neck squamous cell carcinoma patients who are at risk of developing local recurrence in a betel quid-prevalent region.

Applications of molecular diagnostics for personalized treatment of head and neck cancer: state of the art

Squamous cell carcinomas of the head and neck are the sixth most frequent tumors worldwide. Risk factors are carcinogenic exposure, infection with the human papillomavirus (HPV) and genetic predisposition. Lymph node metastasis in the neck and HPV status are major prognostic factors. There are several important clinical challenges that determine the research agenda in head and neck cancer. The first is more accurate staging, particularly of occult metastatic lymph nodes in the neck. A second challenge is the lack of biomarkers for personalized therapy. There are a number of treatment modalities that can be employed both single and in combination, but at present only site and stage of the tumor are used for treatment planning. Provided here is an overview of the successes and failures of molecular diagnostic approaches that have been and are being evaluated to address these clinical challenges.

Tumor-related markers in histologically normal margins correlate with locally recurrent oral squamous cell carcinoma: a retrospective study

BACKGROUND

Oral squamous cell carcinoma (OSCC) is characterized by a high rate of local recurrence (LR) even when the surgical margins are considered histopathologically 'normal'. The aim of our study was to determine the relationship between early tumor-related markers detected in histologically normal margins (HNM) and LR as well as disease-free survival in OSCC.

METHODS

The loss of heterozygosity (LOH) of markers on 9p21 (D9s1747, RPS6, D9s162) and 17p13 (TP53) and the immunostaining results of the corresponding mutant P53, P14, P15, and P16 proteins were assessed and correlated with LR and disease-free survival in 71 OSCC patients who had HNM.

RESULTS

Fifteen of 71 patients with HNM developed LR. The presence of the following molecular markers in surgical margins was significantly correlated with the development of LR: LOH on chromosome 9p21 (D9s1747 + RPS6 + D9s162), any LOH, P16, and P53 (chi-square test, P < 0.05). The presence of TP53 LOH, 9p21 LOH, any LOH, P15, P16, P53, P16 + D9s1747, and P53 + TP53 had a significant effect on LR (Kaplan-Meier analysis, P < 0.05). P16 + D9s1747 was the most predictive factor using multivariate Cox analyses.

CONCLUSIONS

Detection of tumor-related markers in histologically 'normal' resection margins may be a useful method for assessing LR in OSCC patients.

Prevalence and implications of elevated microsatellite alterations at selected tetranucleotides in cancer

Elevated microsatellite alterations at selected tetranucleotides (EMAST), a variation of microsatellite instability (MSI), has been reported in a variety of malignancies (e.g., neoplasias of the lung, head and neck, colorectal region, skin, urinary tract and reproductive organs). EMAST is more prominent at organ sites with potential external exposure to carcinogens (e.g., head, neck, lung, urinary bladder and colon), although the specific molecular mechanisms leading to EMAST remain elusive. Because it is often associated with advanced stages of malignancy, EMAST may be a consequence of rapid cell proliferation and increased mutagenesis. Moreover, defects in DNA mismatch repair enzyme complexes, TP53 mutation status and peritumoural inflammation involving T cells have been described in EMAST tumours. At various tumour sites, EMAST and high-frequency MSI share no clinicopathological features or molecular mechanisms, suggesting their existence as separate entities. Thus EMAST should be explored, because its presence in human cells may reflect both increased risk and the potential for early detection. In particular, the potential use of EMAST in prognosis and prediction may yield novel types of therapeutic intervention, particularly those involving the immune system. This review will summarise the current information concerning EMAST in cancer to highlight the knowledge gaps that require further research.

Molecular staging of surgical margins in oral squamous cell carcinoma using promoter methylation of p16(INK4A), cytoglobin, E-cadherin, and TMEFF2

BACKGROUND

Local recurrence in oral squamous cell carcinoma (OSCC) despite clear surgical margins may indicate the presence of residual, sub-microscopic disease. Molecular assessment of surgical margins may provide a greater prognostic sensitivity compared to histopathology. We aimed to determine whether promoter methylation in deep and mucosal resection margins can predict recurrence in OSCC.

METHODS

Forty-eight consecutive OSCC cases were recruited and a 5 mm(3) tumor sample plus 5 deep and 5 mucosal margin samples were snap frozen. Clinical, pathological, adjuvant therapy, and outcome data were recorded. Tumors were informative if >5 % promoter methylation was found for ≥1 of 4 genes using qMSP. Margins were declared molecularly positive if >1 % promoter methylation was found in any margin.

RESULTS

Thirty (63 %) of 48 cases were methylation informative. Mucosal margin samples were largely positive for methylation (26 of 30, 87 %), indicating the presence of field cancerization. Methylation at ≥1 gene promoters in ≥1 deep margin correlated with the presence of close/involved mucosal margins (P = 0.027) and increased pT status (P = 0.027) but not the status of deep margins, recurrence, or survival.

CONCLUSIONS

The current gene panel did not add prognostic information to histopathological reporting of resection margins. Future efforts should concentrate on improving gene selection, informativity, and assay performance in the patient group with intermediate indications for adjuvant therapy.

Clinical significance of molecular alterations in histologically negative surgical margins of head and neck cancer patients

The development of locoregional recurrence is the main reason for treatment failure in head and neck squamous cell carcinomas (HNSCC) and the remaining of tumor cells in surgical margins is associated with recurrence. Surgical margins are considered negative based on histologic assessment of the pathological specimen. However, this method lacks sensitivity in identifying cells that already started malignant transformation but have not yet developed a pathologic phenotype. We investigated the usefulness of assessing the expression of PTHLH, EPCAM, MMP9, LGALS1 and MET for the detection of molecular alterations in histologically negative surgical margins and determine the correlation of these tumor-related alterations with clinical and prognostic parameters. Differential gene expression was determined by quantitative RT-PCR analyses in normal mucosa, HNSCC and negative margin samples. Thirty-eight percent of the histologically negative surgical margins examined were margin-positive for overexpression of at least one of the genes evaluated. Moreover, MMP9 and PTHLH overexpression in the surgical margins was associated with the development of second primary tumors (p=0.002) and lower rates of local control (log rank test p=0.022; HR=4.186; p=0.035), respectively. These findings demonstrate that the overexpression of tumor-related genes in histologically negative surgical margins is a frequent event. The use of qRT-PCR may be an useful tool in detecting actually negative HNSCC surgical margins and the overexpression of specific genes in these margins could be helpful in the identification of patients with a higher risk of developing second primary tumors and local recurrences, thus aiding the surgeon in the delineation of the HNSCC resection extent and helping in the planning of adjuvant therapy.

Loss of heterozygosity at 9p and p53 immunopositivity in surgical margins predict local relapse in head and neck squamous cell carcinoma

A major problem in head and neck cancer surgery is the high rate of local relapse (LR). In at least 25% of the surgically treated head and neck squamous cell carcinoma (HNSCC) patients, a genetically defined preneoplastic lesion, also known as "field," can be detected in the surgical margins. A remaining field may be an important cause for the development of LR. The aims of our study are (i) to investigate whether HNSCC patients with an unresected field are more likely to develop LR, and (ii) to identify molecular risk factors that predict malignant transformation of field. We retrospectively studied 35 HNSCC patients of whom 16 patients developed LR and 19 patients remained disease-free for at least 4 years. Loss of heterozygosity (LOH) at chromosomes 3p, 9p and 17p, p53 immunostaining, Ki-67 immunostaining and histopathological grading of all available paraffin-embedded surgical margins was performed, and related to LR. Significant associations were determined by Kaplan-Meier analysis and Cox-proportional hazard models. We show that presence of field is significantly associated with LR and that LOH at 9p and p53 immunostaining have the most predictive potential (hazard ratios 3.17 and 3.46, and p values 0.027 and 0.017, respectively). The combination of LOH at 9p and/or a large p53 positive field is most predictive (hazard ratio 7.06 and p = 0.01). Presence and grade of dysplasia was not associated with LR. These data may have major impact for future diagnostic workup of surgically treated HNSCC patients.

Molecular analysis of surgical margins in head and neck cancer: more than a marginal issue

The relatively modest survival of patients surgically treated for advanced HNSCC can partly be explained by the development of local relapse. It is important that surgeons are able to predict which patients are at high risk to develop local relapse, since clinical management can be tailored. Local relapse after resection of a primary HNSCC is easily explained, when tumour is detected in the surgical margins and thus residual tumour is likely to remain in the patient, but the pathobiology is more complex in cases where the margins are histologically tumour-free. Molecular studies indicate that there are two different mechanisms responsible in these cases. First, small clusters of residual tumour cells that are undetectable on routine histopathological examination (known as minimal residual cancer: MRC) proliferate and this forms the basis of recurring cancer. A second cause of relapse is a remaining field of preneoplastic cells that is struck by additional genetic hits leading to invasive cancer. It is likely that within this field, that can be over 7cm in diameter, the primary carcinoma has also emerged. Despite careful histopathological examination of the surgical margins of the primary carcinoma, it is at present not reliably possible to predict which patient will develop local relapse. Herein we focus on new developments regarding the analysis of margins, causes of local relapse, and how novel molecular techniques can be of help in a more accurate risk assessment. Critical analysis of the studies that have been published thus far shows that there is a list of promising markers, based on protein expression (immuno-histochemistry) and nucleic acid analysis. Further studies should be focused on validation and assessment of the clinical utility of these markers. Margin analysis should reveal whether one is dealing with residual cancer cells that might be treated by post-operative radiotherapy or with preneoplastic fields that remained behind. For this latter entity, there is no intervention available at present, except for a more intensive surveillance.

Significance of promoter hypermethylation of p16 gene for margin assessment in carcinoma tongue

BACKGROUND

Loss of p16 expression by promoter hypermethylation has been reported as an early event in the development of oral cancer. The aim of our study was to explore the prognostic implications of presence of promoter hypermethylation of p16 gene in surgical margins in carcinoma tongue.

METHODS

A prospective analysis of 38 patients with resectable carcinoma tongue was carried out. DNA from tumor and the surgical margins was assessed by methylation-specific polymerase chain reaction. Follow-up duration was 17 to 37 months.

RESULTS

About 86.8% of tumors showed promoter hypermethylation of p16 gene. Out of 30 patients with histologically free margins, 43.3% showed positivity on molecular assessment. Patients with positive molecular margins had a 6.3-fold increased risk of having local recurrence as compared to patients with negative margins.

CONCLUSION

Promoter hypermethylation of p16 gene may serve as a useful molecular marker for predicting local recurrence in carcinoma tongue.

Quantitative methylation analyses of resection margins predict local recurrences and disease-specific deaths in patients with head and neck squamous cell carcinomas

This study sought to determine whether the presence of hypermethylated genes in the surgical margins can predict local recurrences in head and neck squamous cell carcinomas (HNSCCs). We prospectively collected tumour and surgical margin specimens from patients with HNSCCs who had undergone surgical resections. Quantitative methylation-specific PCR (QMSP) of CDKN2A, CCNA1 and DCC were performed in these specimens and correlated with clinical data. Of the 42 patients eligible for the study, 27 were hypermethylation informative for the above three genes. This latter group was associated with longer disease-free survivals (P=0.007) and longer time to disease-specific deaths (P=0.004). Multivariate analyses confirmed hypermethylation non-informative tumours as an independent prognosticating factor for disease-specific deaths (risk ratio 3.8, P=0.026). Quantitative MSP of the margins of 24 hypermethylation informative tumours revealed that 11 patients had molecularly positive margins, of which, five developed disease-specific events (DSEs, three local recurrences and two metastases), compared to none in patients with molecularly negative margins, after a median follow-up of 48 months. Log-rank analyses showed that molecularly positive margins were associated with shorter time to local recurrences and disease-specific deaths (P=0.03 and 0.01, respectively). This study demonstrated that QMSP of hypermethylated promoters in surgical margins predicted all the local recurrences in our series of HNSCC patients. We have also identified hypermethylation non-informative tumours as an independent predictor for the development of DSEs.

The convergent development of molecular-targeted drugs for cancer treatment and prevention

Advances in our understanding of multistep and field carcinogenesis are erasing the clear demarcation of intraepithelial neoplasia from invasive neoplasia. The growing ability to define a very high risk of cancer is forging important commonalities between prevention and therapy, such as in potential prognostic/predictive markers, agents, and side effects that patients would be willing to tolerate, and the logistics of definitive trials. The emergence of promising new molecular-targeted agents and new technologies for screening and early detection provides new opportunities for applying clinical trial designs that integrate therapy and prevention end points. Such trials may be used to facilitate targeted drug development and help identify strategies for both cancer prevention and advanced cancer therapy. These several advances are creating a convergence of cancer therapy with cancer prevention that promises to streamline the development of targeted drugs and improve the control of major cancers.

The clinical relevance of microsatellite alterations in head and neck squamous cell carcinoma: a critical review

Triggered by the existing confusion in the field, the current paper aimed to review the current knowledge of both microsatellite instability (MSI) and loss of heterozygosity (LOH) detected by microsatellite markers in head and neck squamous cell carcinoma (HNSCC), and to provide the reader with an assessment of their prognostic and predictive value in this tumor type. For both MSI and LOH, various detection methods were included such as mono- and polynucleotidemarkers and gel- as well as automated analyses. Only studies based on PCR techniques with microsatellite markers were considered. Taking the methodological problems occurring in investigations with microsatellite markers into account, LOH seems to be more common than MSI in HNSCC. Although both types of microsatellite alterations have been correlated with clinicopathological features of this tumor type, only LOH seems to have a clear prognostic value. The predictive value of both MSI and LOH is debatable. More research has to be performed to clearly establish LOH detection as a translational application in the HNSCC field, aiming to predict response to treatments or outcome, and eventually to use as a therapeutic target.

Frequent genomic alterations in epithelium measured by microsatellite instability following allogeneic hematopoietic cell transplantation in humans

Although typically found in cancers, frameshift mutations in microsatellites have also been detected in chronically inflamed tissues. Allogeneic hematopoietic cell transplantation (HCT) may potentially produce chronic tissue stress through graft-versus-host reactions. We examined non-neoplastic epithelial tissues (colon, buccal) obtained 1 to 5061 days after human allogeneic HCT for the presence of genomic alterations at 3 tetranucleotide and 3 mononucleotide microsatellite loci. Novel bands indicative of microsatellite instability (MSI) at tetranucleotide repeats were detected in laser-microdissected colonic crypts and in buccal smears of 75% and 42% of patients who received an allograft, respectively. In contrast, no MSI was found in similar tissues from control subjects and from patients after intensive chemotherapy or in buccal cells from patients after autologous HCT. The MSI found in colon, which was often affected by graft-versus-host disease, was not due to loss of expression or nitrosylation of DNA repair proteins. MSI in clinically intact oral mucosa was more frequently found at later time points after HCT. MSI was also found in 3 posttransplant squamous cell cancers examined. Our data show that genomic alterations in epithelium regularly occur after allogeneic HCT and may be implicated in the evolution of posttransplantation diseases, including secondary cancer.