Oral cancer

Utility of gamma-glutamyl transpeptidase to lymphocyte count ratio in predicting prognosis of patients with oral cancer: A prospective cohort study in Southeastern China

BACKGROUND

To assess the prognostic role of gamma-glutamyl transpeptidase to lymphocyte count ratio (GLR) and develop a prognostic nomogram for patients with oral cancer.

METHODS

A prospective cohort (n = 1011) was conducted during July 2002 to March 2021 in Southeastern China.

RESULTS

The median follow-up time was 3.5 years. Multivariate Cox regression (OS: HR = 1.51, 95% CI: 1.04, 2.18) and Fine-Gray model (DSS: HR = 1.68, 95% CI: 1.14, 2.49) both showed that high GLR could act as an indicator of poor prognosis. A nonlinear dose-response relationship was observed between continuous GLR and the risk of all-cause mortality (p for overall = 0.028, p for nonlinear = 0.048). Compare with TNM stage, time-dependent ROC curve proved that GLR-based nomogram model performs better in predicting prognosis (the area under curve for 1-, 3-, and 5-years mortality: 0.63, 0.65, and 0.64 vs. 0.76, 0.77, and 0.78, p < 0.001).

CONCLUSION

GLR might be a useful tool in predicting prognosis for patients with oral cancer.

Evaluation of salivary gamma-glutamyl transpeptidase as a biomarker in oral squamous cell carcinoma and precancerous lesions

Background:

Oral cancer is such a common malignancy, but its manifestations are usually asymptomatic, and by the time the lesion is diagnosed its invasion is deep. This makes the survival rate poor and also the treatment rendered during such stages is extensive and debilitating. In this regard, a novel approach has been advocated in the estimation of biomarkers in the body fluids. Gamma-glutamyl transpeptidase (GGT)/gamma-glutamyl transferase is an enzyme that is essential for the absorption of amino acids, especially in the degradation of glutathione. Its activity is increased in oral cancer and precancerous lesions.

Aims and Objectives:

The purpose of this study was to assess the activity and concentration of GGT in precancerous and cancerous patients in comparison with normal patients and also to assess its efficacy as an effective tumor marker.

Materials and Methods:

The study population comprised a total of 75 patients who were categorized into three groups as normal patients (25 cases in Group A), patients with precancerous lesions (25 patients in Group B) and patients with oral squamous cell carcinoma (25 cases in Group C). 5 ml of whole unstimulated saliva collection was done, it was centrifuged at 3000 rpm for 15 min and the supernatant thus obtained was used for the estimation of GGT levels. The detection was done by photometric method reading the absorbance at 405 nm.

Results:

Group A patients had values of GGT ranging from 4 to 30U/L with a mean of 16.7 ± 1.94U/L. Group B had activity of GGT ranging from 39 to 65 U/L with a mean of 50.4 ± 1.67U/L. In group C, the evaluated GGT activity was between 53 and 86 U/L and the mean was 70 ± 2.37 U/L. Statistical analysis using Chi-square test was conducted. Correlations between Group A and Group B and between Groups A and C showed a statistically significant relation (P < 0.005).

Conclusion:

Salivary gamma-glutamyl transferase activity can be used effectively as a tumor marker, and further studies with a larger sample size can be done to correlate this finding.

Significance of the neutrophil-to-lymphocyte ratio in young patients with oral squamous cell carcinoma

Background

The main goal of this study was to evaluate the prognosis of young patients with oral squamous cell carcinoma (SCC) with a focus on the value of the pretreatment neutrophil-to-lymphocyte ratio (NLR).

Materials and methods

Young (≤40 years old) patients with oral SCC were retrospectively enrolled, and each young patient was matched with an old (≥60 years old) oral SCC patient. Associations between the NLR and clinicopathological variables were analyzed by the chi-square test, and the Kaplan–Meier method was used to analyze recurrence-free survival (RFS) and disease-specific survival (DSS) rates.

Results

A total of 103 young patients were enrolled, and compared to the old group, the young group had a significantly lower NLR value (p=0.012). In the young group, the 5-year RFS and DSS rates were 82% and 85%, respectively. In the old group, the 5-year RFS and DSS rates were 65% and 71%, respectively, and the differences between the groups were significant (both p<0.05). In the young patients with an NLR≤2.56, the 5-year DSS rate was 93%, while in the young patients with an NLR >2.56, the 5-year DSS rate was 76%. This difference was significant (p=0.020). A further Cox model analysis confirmed that the NLR was an independent prognostic factor for DSS.

Conclusion

Young patients with oral SCC have a better prognosis than old oral SCC patients, and the NLR is significantly associated with DSS in young patients.

Cucurmin, anticancer, & antitumor perspectives: A comprehensive review

Cucurmin, a naturally yellow component isolated from turmeric, ability to prevent various life-style related disorders. The current review article mainly emphasizes on different anticancer perspectives of cucurmin, i.e., colon, cervical, uterine, ovarian, prostate head and neck, breast, pulmonary, stomach and gastric, pancreatic, bladder oral, oesophageal, and bone cancer. It holds a mixture of strong bioactive molecule known as cucurminoids that has ability to reduce cancer/tumor at initial, promotion and progression stages of tumor development. In particular, these compounds block several enzymes required for the growth of tumors and may therefore involve in tumor treatments. Moreover, it modulates an array of cellular progressions, i.e., nitric oxide synthetase activity, protein kinase C activity, epidermal growth factor (EGF) receptor intrinsic kinase activity, nuclear factor kappa (NF-kB) activity, inhibiting lipid peroxidation and production of reactive oxygen species. However, current manuscript summarizes most of the recent investigations of cucurmin but still further research should be conducted to explore the role of curcumin to mitigate various cancers.

Conversion of Normal To Malignant Phenotype: Telomere Shortening, Telomerase Activation, and Genomic Instability During Immortalization of Human Oral Keratinocytes

Normal somatic cells terminate their replicative life span through a pathway leading to cellular senescence, which is triggered by activation of p53 and/or pRb in response to critically shortened telomere DNA. Potentially neoplastic cells must first overcome the senescence checkpoint mechanisms and subsequently activate telomerase to propagate indefinitely. Although telomerase activation is closely associated with cellular immortality, telomerase alone is not sufficient to warrant tumorigenicity. Environmental factors, including chemical carcinogens and viral infection, often contribute to aberrant changes leading to tumorigenic conversion of normal cells. Of particular importance in oral cancer development are tobacco-related chemical carcinogens and human papillomavirus (HPV) infection. To describe the molecular mechanisms by which these environmental factors facilitate the genesis of oral cancer, we first established an in vitro multistep oral carcinogenesis model by sequential exposure of normal human oral keratinocytes (NHOK) to "high risk" HPV and chemical carcinogens. Upon introduction of the HPV genome, the cells bypassed the senescence checkpoint and entered into an extended, but not immortal, life span during which telomere DNA continued to shorten. In a few immortal clones surviving beyond the crisis, we found a marked elevation of telomerase activity and stabilization of telomere length. Furthermore, the E6 and E7 oncoproteins of "high risk" HPV disrupted the cell cycle control and DNA repair in immortalized HOK, and enhanced mutation frequency resulting from genomic instability. However, HPV infection alone failed to give rise to a tumorigenic cell population, which required further exposure to chemical carcinogens in addition to HPV infection. Analysis of the data presented suggests that oral carcinogenesis is a series of discrete genetic alterations that result from a continued genotoxic challenge by environmental risk factors. Our in vitro model may be useful for investigators with interest in furthering our understanding of oral carcinogenesis.

Candida and calcofluor white: Study in precancer and cancer

Background:

The interest in oral candidosis has waxed and waned from the period of Hippocrates. The acquired immune deficiency syndrome (AIDS) epidemic has certainly bolstered these figures on oral candidosis, with diabetes and oral cancer being no exception. A need for rapid detection of Candida is made possible by the use of Calcofluor - White (CFW) stain when examined under a fluorescence microscope. The present study was aimed at assessing the efficacy of CFW is compared to Gram stain and periodic acid Schiff (PAS) in detection of Candida in oral precancer and cancer.

Materials and Methods:

The study group consisted of patients with precancer (n=45), cancer (n=45), and control group (n=45). Presence of Candida was confirmed by culture inoculation along with a germ tube and carbohydrate fermentation test. The cytopathological smears were analyzed by papanicolaou - CFW and Gram staining, whereas, tissue sections were stained by PAS and CFW staining.

Results:

Candida albicans was the predominant species identified. A highly significant association of Candida was seen more often in cancer than in precancer. Both in cytology and histopathology Candida detection by CFW was higher. In precancer it was 48.88% in smears and 40% in tissue sections, whereas, in cancer 60% in smears and 55.55% in histopathology.

Conclusion:

Among the various diagnostic tools used in the present study, the use of CFW is seen to be a simple, effective, rapid, and reliable method, both in cytopathology and histopathology.

Outcome of oral tongue squamous cell carcinoma in patients with and without known risk factors

BACKGROUND

Tobacco smoking and high alcohol consumption are considered major risk factors of oral tongue squamous cell carcinoma. This study compared disease outcome between patients with and without known risk factors.

METHODS

Patients with oral tongue squamous cell carcinoma treated at two major medical centers from 1994 to 2008 were identified by cancer registry search. The medical files were reviewed for background-and-disease-related data, risk factors, and outcome.

RESULTS

The study sample consisted of 291 patients: 175 had a history of heavy tobacco smoking and alcohol abuse and 116 did not. Comparison of the patients without risk factors between the two centers yielded no differences in background features. Men accounted for 74% of the total patients with risk factors and comprised 77% of the risk-factor group. The risk-factor group was characterized by a significantly higher mean tumor grade (p=0.0001) and greater tumor depth of invasion (p=0.022) than the non-risk-factor group. The 5-year local and regional control rates were 85.3% and 74%, respectively, with no significant difference between the groups. The 5-year overall survival rate was 68% in the risk-factor group and 64% in the non-risk-factor group (p=NS). Separate analysis of patients aged <40 years at diagnosis revealed a worse overall (p=0.015) and disease-free survival (p=0.038) in those without risk factors.

CONCLUSIONS

The outcome of oral tongue carcinoma is similar in patients with and without risk factors. The worse prognosis in younger patients (<40 years) without risk factors suggests that the pathogenesis in these cases involves factors other than smoking and alcohol.

The use of animal models for cancer chemoprevention drug development

Animal models currently are used to assess the efficacy of potential chemopreventive agents, including synthetic chemicals, chemical agents obtained from natural products, and natural product mixtures. The observations made in these models as well as other data are then used to prioritize agents to determine which are qualified to progress to clinical chemoprevention trials. Organ-specific animal models are employed to determine which agents or classes of agents are likely to be the most effective at nontoxic doses to prevent organ-specific forms of cancer. These results are then used to target specific organs in high-risk populations in clinical trials. The animal models used are either carcinogen-induced with carcinogens specific for particular organ sites or they are transgenic/mutant animals with insertions, deletions, or mutations at targeted gene sites known to enhance cancers in a specific organ. Animal tumor models with characteristics favorable to chemoprevention studies are available for cancers of the lung, colon, skin, bladder, mammary, prostate, head and neck, esophagus, ovary, and pancreas. In addition to single-agent dose-response testing, such models are frequently used for testing combinations of agents, testing different routes of administration, evaluating surrogate endpoint biomarkers, and generating initial pharmacokinetics and toxicology data. For some of the more standard animal models there is significant correlation with human chemopreventive trial results. There are a growing number of positive human chemoprevention trials that have used agents or combinations that were positive in animal testing. There have been fewer negative human clinical trials, but their results again correlate with negative animal results. Clearly the validation of animal models to predict the efficacy of agents in human clinical trials will await further human data on positive and negative outcomes with chemopreventive agents. Whether validated or not, animal efficacy data remain central to the clinical trial decision-making process.

Relationship between chronic trauma of the oral mucosa, oral potentially malignant disorders and oral cancer

BACKGROUND

Oral cancer represents 2%-5% of all cancers, being one of the 10 most frequent ones. Apart from oral cancer risk factors already described in literature, such as tobacco and alcohol consumption, others emerging risk factors have been proposed, such as chronic irritation from dental factors. The aim of this work was to assess the influence of chronic trauma of the oral mucosa (CTOM) in patients with oral potentially malignant disorders (OPMD) and cancer.

METHODS

A retrospective study of 406 patients (both sexes; aged between 18 and 80 years; with OPMD and cancer) who attended the Department of Clinical Stomatology A of the National University of Cordoba was performed by non-probabilistic sampling. The association of variables and outcome variable diagnosis, with levels control, OPMD, oral cancer, was evaluated by multinomial regression model.

RESULTS

Population under study was represented by 72% of control patients, 16% patients with OPMD and 11% of patients with oral cancer. It was observed a significant association between diagnosis and CTOM (P = 0.000), after adjustment of confounding factors (smoking and drinking habits, sex, cancer inheritance and denture use).

CONCLUSIONS

Our results suggest that CTOM is, together with other factors, an important risk factor in patients with oral cancer diagnosis, but not for patients with OPMD.

Overexpression of cyclooxygenase-2 in rat oral cancers and prevention of oral carcinogenesis in rats by selective and nonselective COX inhibitors

Oral squamous cell carcinomas induced in rats by 4-nitroquinoline-1-oxide (NQO) show substantial overexpression of cyclooxygenase-2 (COX-2) when compared with adjacent phenotypically normal oral tissues. By contrast, neither 5-lipoxygenase (LOX) nor 12-LOX is overexpressed in rat oral cancers. Two chemoprevention studies were done to test the resulting hypothesis that COX-2 is a useful target for oral cancer chemoprevention in the rat. In both studies, male F344 rats received drinking water exposure to NQO (20 ppm) for 10 weeks, followed by administration of chemopreventive agents from week 10 until study termination at week 26. In the first study, groups of rats were fed basal diet (control), or basal diet supplemented with the selective COX-2 inhibitor celecoxib (500 or 1,500 mg/kg diet), the nonselective COX inhibitor piroxicam (50 or 150 mg/kg diet), or the 5-LOX inhibitor zileuton (2,000 mg/kg diet). In the second study, rats were fed basal diet (control) or basal diet supplemented with nitric oxide-naproxen (180 or 90 mg/kg diet), a nonselective COX inhibitor that shows reduced gastrointestinal toxicity. When compared with dietary controls, celecoxib decreased oral cancer incidence, cancer invasion score, and cancer-related mortality. Piroxicam decreased cancer-related mortality and cancer invasion score, whereas nitric oxide-naproxen decreased oral cancer incidence and cancer invasion score. By contrast, zileuton showed no chemopreventive activity by any parameter assessed. These data show that both selective and nonselective inhibitors of COX-2 can prevent NQO-induced oral carcinogenesis in rats. The chemopreventive activity of COX inhibitors may be linked to overexpression of their enzymatic target in incipient oral neoplasms.

The chemopreventive agent development research program in the Division of Cancer Prevention of the US National Cancer Institute: an overview

Chemoprevention is an innovative area of cancer research that focuses on the development of pharmacological, biological, and nutritional interventions to prevent, reverse, or delay carcinogenesis. Over the past two decades the Division of Cancer Prevention of the US National Cancer Institute has organized a research and development program to provide resources and infrastructure to the research community for the clinical evaluation of potential cancer preventive agents. This program now encompasses preclinical agent and molecular target identification, in vitro and in vivo screening, efficacy and intermediate endpoint testing, pharmacology and toxicology assessments, and finally chemical synthesis and manufacturing leading to Investigational New Drug applications and clinical studies. In this review, examples of agents currently in development, preclinical testing models, and phase 1 and 2 clinical studies are described. Continued commitment to cancer prevention will significantly reduce the economic and medical burden of cancer.

In vitro secreted aspartyl proteinase activity of Candida albicans isolated from oral diseases and healthy oral cavities

The in vitro secreted aspartyl proteinase (SAP) activity of Candida albicans isolated from a variety of oral conditions, including healthy oral cavities, was determined. SAP activity (units/10(6) cells/ml, +/-SD) was 0.28 +/- 0.33 for pseudomembranous candidosis isolates (n = 18), 0.35 +/- 0.46 for chronic erythematous candidosis isolates (n = 21) and 0.30 +/- 0.32 for chronic hyperplastic candidosis isolates (n = 50). SAP activity of 0.19 +/- 0.22 was recorded for isolates from squamous cell carcinoma (n = 18), 0.26 +/- 0.37 for burning mouth syndrome isolates (n = 29), 0.25 +/- 0.38 for isolates from xerostomia (n = 15) and 0.39 +/- 0.50 for isolates from lichen planus (n = 13). The SAP activity of isolates from oral disease states was significantly (P < 0.05) higher than that recorded for 28 isolates from healthy mouths (activity of 0.04 +/- 0.03). However, there was no significant difference in the SAP activity between the three forms of clinical oral candidosis (P > 0.05). SAP activity was inhibited in control samples containing the SAP inhibitor, pepstatin A. These results indicate that C. albicans strains associated with oral disease have inherently higher SAP activity.

[The frequency of Candida sp. in biopsies of oral mucosal lesions]

Candidosis is the most common fungal infection in the oral cavity, and is usually associated with local and systemic predisposing factors. The occurrence and relevance of Candidal infection in oral lesions such as liquen planus, leukoplakias and carcinomas are still to be understood. The aim of the present study was to define the frequency of infection by Candida sp. on biopsies of oral mucosal lesions and associate its presence with malignant and dysplastic lesions. Histopathology reports issued between 1990 and 2001 inclusive were reviewed. Three sections of each mucosal biopsy were stained using the periodic acid-Schiff (PAS) technique. From the 832 biopsies 27.2% were PAS positive, of which 83.25% were obtained from male patients. There was positive association between fungic infection and mild, moderate and severe epithelial dysplasia, squamous cell carcinoma and hiperqueratosis (p < 0.05). There was no association between fungic infection and inflammatory fibrous hyperplasia, hyperkeratosis, lichen planus and pyogenic granuloma (p < 0.05). The frequency of infection in the tongue was significantly higher (p < 0.05) than in the other sites. Our results do not show a causal relation between Candida sp. and dysplastic lesions and carcinomas, but do confirm the higher presence of that microrganism in those lesions.

The association between Viadent use and oral leukoplakia

Recently, leukoplakia of the maxillary vestibule was described in patients with no traditional risk factors but who had used Viadent products. We designed a case-control study to evaluate the hypothesis that Viadent users were more likely to have lesions. One hundred and forty-eight cases and controls were identified through the Section of Oral and Maxillofacial Pathology. Cases and controls were administered a questionnaire about Viadent use and other known risks. Results of crude, stratified, and logistic regression analyses showed that use of Viadent products was a risk indicator for leukoplakia (adjusted OR = 9.7, 95% CI = 4.7-21.6), with a strong dose-response relation.

The epidemiology of tongue cancer: a review of global incidence

The tongue (141 ICD-9) is the most common intraoral site for cancer in most countries, however its global epidemiology shows significant geographic variation. This review paper summarises the global incidence of cancer of the tongue using cancer maps and references to recent studies from various locations. Tongue cancer remains a serious health problem in many countries including India (male incidence rates up to 6.5 per 100,000 per annum) and parts of Europe (male incidence rates in France up to 8.0 per 100,000 per annum). It is noted that as with other forms of oral cancer the majority of population-based data for tongue cancer comes from the Western world with a paucity of reliable data from the so-called developing countries. The tongue remains the most common intraoral site for oral cancer worldwide and in a number of countries it is a serious public health problem with significant morbidity and mortality. While the incidence of tongue cancer appears to be stable or falling in some regions of the world, in other areas it is rising, particularly among younger people.

Possible mechanisms by which alcohol may influence the development of oral cancer--a review

Although pure ethanol has never been shown to be carcinogenic in laboratory experiments, alcoholic beverages are now recognised as being important aetiological factors in the development of oral cancer. Despite this, the exact mechanism by which alcohol may exert an influence upon the oral mucosa has received less attention. An overview of the association of alcohol and oral cancer, both in combination with tobacco and without, is provided and consideration given to some of the pathways by which alcohol exerts its effect upon the oral mucosa.

Correlation between HPV types associated with oral squamous cell carcinoma and cervicovaginal cytology: An in situ hybridization study

Epidemiologic and clinical evidence suggests a possible relationship between the human papillomavirus types found in oral squamous cell carcinoma and cervicovaginal cancer. To try to address this question, we analyzed by in situ hybridization 50 paraffin-embedded biopsies of oral squamous cell carcinomas and their corresponding Papanicolaou smears using nonradioactive DNA probes for human papillomavirus type 6/11 and 16/18. This analysis revealed that 70% (35 of 50) of oral squamous cell carcinomas and 56% (28 of 50) of Papanicolaou smears were positive for one or both of these human papillomavirus DNA probes. In 23 of the 28 patients who were positive for human papillomavirus sequences in the cervicovaginal tract, we found the same human papillomavirus type in the oral cavity. Five of the positive in situ hybridization Papanicolaou smears were associated with negative in situ hybridization oral squamous cell carcinomas. Our data suggest that after a primary infection by human papillomavirus, other mucosal sites may eventually become infected. Local environmental factors may contribute to the pathogenesis of lesions such as oral squamous cell carcinoma.

Tumor differentiation-dependent local immunity in human head and neck cancers

Distribution of markers of local cell-mediated immunity was examined in oral tumors exhibiting different histological stages of differentiation. Using a RT-PCR-based semiquantitative technique we determined levels of Langerhans cells, CD4- and CD8-positive T-cells, macrophages/NK cells, beta2-microglobulin and IFN-gamma mRNAs from tissue biopsies. A positive correlation was found between levels of these immunological markers and the tumor differentiation stage. Since tumor differentiation may correlate with the prognosis and response to various treatment modalities, our results may be useful clinically.

An atypical verrucous carcinoma of the tongue arising in a patient with oral lichen planus associated with hepatitis C virus infection

Recently, a clinical relationship between oral lichen planus (OLP) and hepatitis C virus (HCV) infection has been suggested, but the role of this virus on the course of OLP is unknown. We report an unusual lingual localisation of verrucous carcinoma arising in a patient with histologically confirmed OLP and HCV infection diagnosed with second generation enzyme-linked immunosorbent assay and recombinant immunoblot assay. Serum HCV-RNA detected using nested reverse transcriptase polymerase chain reaction (RT-PCR) confirm HCV replication. No classical risk factors associated with verrucous carcinoma were present.

Immunohistochemical demonstration of epithelial glutathione S-transferase isoenzymes in normal, benign, premalignant and malignant human oral mucosa

The expression and localization of glutathione S-transferase (GST) isoenzymes in the epithelium of normal oral mucosa (n = 9), overlying reactive fibrous hyperplasia (n = 9), and of potentially malignant [leukoplakia (n = 25), submucous fibrosis (n = 12), verrucous hyperplasia (n = 16)] and malignant [squamous cell carcinoma (n = 36), verrucous carcinoma (n = 13)] oral lesions were examined immunohistochemically using polyclonal antibodies raised against GST isoenzymes (alpha, mu and pi) with the standard avidin-biotin-peroxidase complex (ABC) method. GST alpha, mu and pi were almost completely absent in the epithelium of normal oral mucosa and overlying benign fibrous tissues. GST alpha staining was cytoplasmic and focally positive, while GST mu staining was similar to but weaker than that seen for GST alpha. GST pi showed both cytoplasmic and nuclear staining and was expressed in 60% of leukoplakias with mild dysplasia (n = 15), 80% of leukoplakias with moderate to severe dysplasia (n = 10). 75% of submucous fibrosis samples (n = 12), 75% of verrucous hyperplasias (n = 16), 77% of verrucous carcinomas (n = 13), 81% of well-differentiated squamous cell carcinomas (n = 26) and 70% of moderate- to poorly-differentiated squamous cell carcinomas (n = 10). In addition, GST pi expression was independent of the state of differentiation of oral cancers. Since GST pi was significantly over-expressed in the oral premalignant and malignant lesions, the kinetics of GST pi-positive cells and the value of GST pi as a tumor marker in oral carcinogenesis need further investigation.

Bionutrition and oral cancer in humans

Tobacco (smoking and smokeless) use and excessive consumption of alcohol are considered the main risk factors for oral cancer (ICD9 140-149). Conspicuous national and international variations in oral cancer incidence and mortality rates, as well as observations in migrant populations, raise the possibility that diet and nutritional status could be an important etiologic factor in oral carcinogenesis. As shown in this report, abuse of alcohol and tobacco has serious nutritional implications for the host, and generates increased production of reactive free radicals as well as eliciting immunosuppression. Maintenance of optimal competence of the immune system is critical for cancer surveillance. Active oxygen species and other reactive free radicals mediate phenotypic and genotypic alterations that lead from mutation to neoplasia. Consequently, the most widely used chemopreventive agents against oral cancer (e.g., vitamins A, E, C, and beta-carotene) are anti-oxidants/free radical scavengers. These anti-oxidants, both natural and synthetic, neutralize metabolic products (including reactive oxygen species), interfere with activation of procarcinogens, prevent binding of carcinogens to DNA, inhibit chromosome aberrations, restrain replication of the transformed cell, suppress actions of cancer promoters, and may even induce regression of precancerous oral lesions such as leukoplakia and erythroplakia. Malnutrition is characterized by marked tissue depletion of anti-oxidant nutrients, including GSH (gamma-glutamyl-cysteinyl-glycine), a key cellular anti-oxidant as well as a modulator of T-cell activation. GSH or its precursor cysteine inhibits activation of the nuclear transcription factor kB(NFkB), and has been shown to be protective against chemically induced oral cancer and leukoplakia. Alcohol-, tobacco-, and/or malnutrition-induced immunosuppression promotes impaired salivary gland function and oral mucosal immunity, a prominent reduction in the number of helper CD4 cells with less marked changes in number of suppressor T-cells, and depressed NK cell activity, among others. These suggest a breakdown in capacity or the malnourished to mount effective tumor surveillance. This review article underscores the compounding but important roles of nutritional/dietary factors in the long-established causal link between abuse of alcohol and tobacco (smoking and smokeless) and oral cancer.

p53 immunostaining as a marker for oral cancer in diagnostic cytopathology--preliminary report

The expression of p53 in oral mucosal disorders is strongly associated with malignant disease. Smears from normal and malignant oral mucosa were investigated for the presence of p53 using CM1 polyclonal antibody against p53 protein. The expression of p53 in smears was compared with the expression of the marker in biopsies from these oral carcinomas. p53 was identified in eight smears from 12 biopsy positive oral cancers. It was not seen in smears from eight p53-negative oral cancers and 40 smears from normal oral mucosa. It is suggested that expression of p53 in smears from a clinically suspicious lesion may be of value in the diagnosis of oral carcinoma.

In vitro and animal studies of the role of viruses in oral carcinogenesis

The linkage of herpes simplex virus (HSV) and human papillomavirus (HPV) to the development of oral cancer has been studied. In spite of the presence of viral nucleic acids in some human oral cancer specimens, HSV alone is not carcinogenic in animals: repeated viral inoculation to mouse or hamster oral mucosa fails to produce tumours or histopathological evidence of malignancy. However, HSV demonstrates co-carcinogenicity in vivo: viral inoculation significantly enhances the oncogenic capacity of chemical carcinogens in the oral cavity of mice and hamsters. Though the detailed mechanisms of HSV cocarcinogenicity are unknown, HSV promotes the chemical carcinogen-induced activation of certain cellular proto-oncogenes and inactivation of p53 tumour suppressor gene. Human papillomaviruses type 16 (HPV-16) and 18 (HPV-18) demonstrate oncogenicity by transforming normal human oral keratinocytes in vitro. While normal cells exhibit a limited life-span, cells transformed by these viruses show immortality and altered morphology in comparison with their normal counterparts. The HPV-immortalised cells contain multiple copies of intact viral genome integrated into cellular chromosomes. These cells also express several viral-specific mRNAs including viral E6/E7 mRNAs. Notably, these cells contain low levels of p53 protein and overexpressed cellular myc proto-oncogene compared to their normal counterpart; however, the immortilised cell lines are non-tumorigenic in nude mice.

Assessment of p53 protein expression in normal, benign, and malignant oral mucosa

Recent studies have shown the accumulation of high levels of p53 protein to be associated with malignant disease, within a range of tissues. This paper assesses p53 expression in oral mucosal disease. Biopsies were obtained from a range of oral disorders which included normal, benign, premalignant, and malignant oral tissue. In addition, oral smears were obtained from a limited number of patients with biopsy-proven oral cancer. Expression of the p53 protein was assessed using the polyclonal antibody CM1, together with a standard immunoperoxidase technique. A total of 37 oral cancers were assessed, of which 20 were found to express the p53 protein (54 per cent of cases). The p53 protein was not identified in normal, benign, or premalignant oral mucosa (54 cases). The identification of p53 within biopsies of oral mucosal lesions would appear to correlate with oral malignancy.