Sensitivity to chromosomal breakage as risk factor in young adults with oral squamous cell carcinoma.

OBJECTIVE: Oral squamous cell carcinoma (OSCC) may develop in young adults. In contrast to older patients, the well-known etiological factors, exposure to tobacco and alcohol, play a minor role in the carcinogenesis in this patient group. It has been suggested that an intrinsic susceptibility to environmental genotoxic exposures plays a role in the development of OSCC in these patients. The hypothesis was tested whether young OSCC patients have an increased sensitivity to induced chromosomal damage. SUBJECTS AND METHODS: Fourteen OSCC patients with an average age of 32 years (range 20-42) were selected. Peripheral blood lymphocytes and skin fibroblasts of patients and 14 healthy controls were subjected to the chromosome breakage test with Mitomycin C. This test is routinely used to identify Fanconi anemia patients, who are well-known for their inherited high sensitivity to this type of DNA damage, but also for the high risk to develop OSCC. Human papilloma virus status of the carcinomas was also determined. RESULTS: None of the 14 young patients with OSCC had an increased response in the MMC-chromosomal breakage test. All tumors tested negative for human papilloma virus. CONCLUSION: No evidence was obtained for the existence of a constitutional hypersensitivity to DNA chromosomal damage as a potential risk factor for OSCC in young adults.

Molecular screening of oral precancer.

OBJECTIVES: Early detection and treatment of high risk premalignant mucosal changes of the oral cavity, will expectedly improve survival and reduce treatment-related morbidity. Aims of this study were to evaluate a non-invasive screening approach and to assess the value of molecular markers to identify patients at risk for oral cancer. MATERIALS AND METHODS: Exfoliated cells and biopsies were obtained from oral leukoplakia lesions of 43 patients, of whom six developed oral cancer. All samples were investigated for loss of heterozygosity (LOH) at chromosomes 3p, 9p, 11q and 17p using microsatellite markers. On the biopsy specimen additional immunohistochemical staining for p53, TP53 mutation analysis and histopathological grading were performed. RESULTS: The analytical sensitivity of the non-invasive assay using exfoliated cells to detect genetic changes present in the lesions was 45% (9 of 20), the specificity was 100% (19 of 19), and the positive predictive value was also 100% (9 of 9). LOH was present in 20 of 39 (51%) of the biopsies with uniformly LOH at 9p. Mutated TP53 and LOH at 9p in the biopsy, as single markers and in combination, were significant risk factors for malignant progression of leukoplakia to oral cancer (Kaplan-Meier analysis, p<0.05). CONCLUSION: A non-invasive genetic screening approach using LOH in exfoliated cells has limited value for monitoring patients with leukoplakia. However, LOH at 9p, but also mutated TP53 in biopsies of oral leukoplakia have a significant association with malignant transformation and are promising candidate biomarkers to predict the risk for malignant progression.

Generation of precursor cell lines from preneoplastic fields surrounding head and neck cancers.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) develops in the mucosal linings of the upper aerodigestive tract. HNSCC may develop in large preneoplastic fields, which are in most cases invisible, but can be detected microscopically and by genetic analysis. METHODS: Cells of mucosal tissue biopsies were cultured and genetically analyzed. Genetic changes in established preneoplastic cultures were compared to the corresponding tumor and surgical margins. RESULTS: Of 45 mucosal tissue biopsies taken from primary tumor resection specimen, 26 were successfully cultured and could be genetically analyzed. In 1 culture, genetic changes were found and an immortalized preneoplastic cell line was obtained with genetic changes that were also found in a surgical margin of the corresponding specimen. CONCLUSION: Our data show that noninvasive fields surrounding HNSCC may consist of immortalized preneoplastic cell clones. Our preneoplastic cell line is a valuable tool to develop and test treatment strategies for precursor fields in patients with HNSCC.

Molecular diagnosis of minimal residual disease in head and neck cancer patients.

AIM: Locoregional recurrences and distant metastases in adequately treated head and neck squamous cell carcinoma (HNSCC) patients have a dismal effect on survival. Tumor cells that escape histopathological detection might be the prime cause of this effect. We evaluated whether minimal residual cancer (MRC) in deep surgical margins and disseminated tumor cells (DTCs) in bone marrow aspirates are associated with clinicohistopathological parameters and outcome. METHODS: Submucosal samples of deep resection margins of 105 HNSCC patients with histopathologically tumor-free surgical margins were analysed for the presence of MRC using hLy-6D qRT-PCR. Bone-marrow aspirates of 76 of these patients were analysed for DTCs by immunocytochemical staining. Presence of molecular-positive deep surgical margins, presence of DTC in bone marrow aspirates, and clinicohistopathological parameters were tested for associations with survival parameters by univariate and multivariate analyses. RESULTS: In addition to lymph node stage, it appeared that vasoinvasive growth and particularly infiltrative growth pattern are significant predictors for locoregional recurrence (p = 0.041 and p = 0.006, respectively) and disease-free survival (p = 0.014 and p = 0.008, respectively). Remarkably, neither the presence of molecular-positive deep surgical margins nor that of DTC in bone marrow aspirates were significantly related to outcome. CONCLUSIONS: The presence of vasoinvasive and infiltrative growth in HNSCC tumor specimens are significant risk-factors for locoregional recurrence and disease-free survival. At present there seems no role for molecular analysis of deep surgical margins and bone marrow aspirates in predicting outcome with the methods used.

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.

Differential Proteomics Identifies Protein Biomarkers That Predict Local Relapse of Head and Neck Squamous Cell Carcinomas.

PURPOSE: The 5-year survival rates of head and neck squamous cell carcinomas (HNSCC) remain disappointing. HNSCCs develop in precursor fields of genetically altered cells that are often not completely resected when the tumor is excised, causing local relapse. These precursor fields are mostly recognized as dysplasia, but histologic grading cannot reliably predict malignant transformation. Our aim was to discover and validate protein biomarkers that can detect precursor fields and predict local relapse in HNSCC using immunostaining of surgical margins. EXPERIMENTAL DESIGN: We compared paired and genetically characterized normal, precursor, and tumor tissues of eight patients by proteome analysis to identify differentially expressed proteins. The prognostic value of candidate protein biomarkers was evaluated by immunohistochemical analysis of 222 surgical margins of 46 HNSCC patients who developed local relapse or remained disease free. Significant associations were determined by Kaplan-Meier survival analysis and Cox-proportional hazards models. RESULTS: Forty proteins showed significant differential expression (false discovery rate-corrected P < 0.05). Most discriminative markers suited for immunostaining were keratin 4 and cornulin. Low expression in the surgical margins of keratin 4 (hazard ratio, 3.8; P = 0.002), cornulin (hazard ratio, 2.7; P = 0.025), and their combination (hazard ratio, 8.8; P = 0.0005) showed a highly significant association with the development of local relapse. Dysplasia grading had no prognostic relevance. CONCLUSIONS: Immunohistochemical assessment of keratin 4 and cornulin expression in surgical margins of HNSCC patients outperforms histopathologic grading in predicting the risk for local relapse. These markers can be used to initiate more frequent and lifelong surveillance of patients at high risk of local relapse, and enable selection for adjuvant treatment or tertiary prevention trials. (Clin Cancer Res 2009;15(24):7666-75).

Molecular detection of minimal residual cancer in surgical margins of head and neck cancer patients.

A great disappointment in head and neck cancer surgery is that 10-30% of head and neck squamous cell carcinoma (HNSCC) patients develop local recurrences despite histopathologically tumor-free surgical margins. These recurrences result from either minimal residual cancer (MRC) or preneoplastic lesions that remain behind after tumor resection. Distinguishing MRC from preneoplasic lesions is important to tailor postoperative radiotherapy more adequately. Here we investigated the suitability of quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) using human Ly-6D (hLy-6D) transcripts as molecular marker to detect MRC in surgical margins. Submucosal samples of deep surgical margins were collected from 18 non-cancer control patients and 67 HNSCC patients of whom eight had tumor-positive surgical margins. The samples were analyzed with hLy-6D qRT-PCR, and the data were analyzed in relation to the clinicohistological parameters. A significant difference was shown between the group of patients with histopathological tumor-positive surgical margins and the non-cancer control group (p<0.001), and the group of patients with histopathological tumor-free surgical margins (p=0.001). This study shows a novel approach for molecular analysis of deep surgical margins in head and neck cancer surgery. The preliminary data of this approach for detection of MRC in deep margins of HNSCC patients are promising.

Screening for oral precancer with noninvasive genetic cytology.

Oral squamous cell carcinomas develop in precancerous fields consisting of genetically altered mucosal epithelial cells. These precancerous fields may appear as clinically visible lesions, in particular, oral leukoplakia, but the large majority remains clinically undetectable. The aim of this study was to assess the potential value of a noninvasive screening approach to detect precancerous fields. As a first step, we developed a suitable assay and investigated 25 leukoplakia patients and 20 noncancer control subjects. Exfoliated cells were removed by a brush from multiple small areas of the oral mucosa, including the leukoplakia. Brushed samples were investigated for allelic imbalance (AI) at chromosomes 3p, 9p, 11q, and 17p using microsatellite markers known to show frequent alterations in oral precancer. AI was absent in all (137) of the samples of the 20 control subjects, yielding a specificity of 100%. AI was detected in exfoliated cell samples of 40% (10 of 25) of the leukoplakia lesions studied. Genetic changes were also found outside the leukoplakia lesions. Most frequent was AI at 9p (9 of 10). The noninvasive assay was validated against the biopsy results of the leukoplakia lesions yielding an estimate of sensitivity of 78% (7 of 9) and a positive predictive value of 100% (7 of 7). Altogether, these results show the feasibility of a noninvasive genetic screening approach for the detection and monitoring of oral precancer. This assay could therefore contribute to the secondary prevention of oral squamous cell carcinoma. The assay also shows promise for the detection of precancerous changes that are not macroscopically visible.