G. R. Ogden

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.

The association between tumour progression and vascularity in the oral mucosa.

Tumourigenesis in experimental models is associated with the formation of new blood vessels (angiogenesis). Recent studies have suggested that tumour angiogenic activity may be inferred in histological sections by measuring the density of the vasculature. The purpose of this study was to determine whether the transition from normal to dysplastic and neoplastic tissue in the oral mucosa is accompanied by quantitative or qualitative changes in the vascularity of the tissue, and how the estimate of vascularity is influenced by the vessel marker and method of assessment. A total of 100 specimens of normal oral mucosa, dysplastic lesions, and squamous cell carcinomas were examined. Sections were immunostained with the pan‐endothelial antibodies to von Willebrand Factor (vWF) and CD31, or with an antibody to the αvβ3 integrin, previously reported to be a marker of angiogenic vessels. Vascularity was quantitated by two different methods: highest microvascular density (h‐MVD) and microvascular volume, as determined by point counting (MVV). The results showed that vascularity, measured by the MVV method using antibodies to either vWF or CD31, increased significantly (P<0·0001) with disease progression from normal oral mucosa, through mild, moderate, and severe dysplasia to early and late carcinoma (76 paraffin‐embedded tissues examined). In contrast, h‐MVD did not discriminate between dysplastic lesions and carcinoma. A similar percentage of the total vessel volume (MVV) and density (h‐MVD) were positive for αvβ3 in 24 frozen tissues examined, including normal oral mucosa. It is concluded that there is a close association between vascularity and tumour progression in the oral mucosa. Morphometric analysis reflecting microvascular volume is more informative than the currently popular analysis of microvascular density. The expression of αvβ3 in the vasculature of oral tissues does not necessarily reflect the presence of angiogenic vessels.

An analysis of mandibular fractures in Dundee, Scotland (1977 to 1985)

A retrospective study was undertaken to assess mandibular fractures presenting over the period 1977-1985 in Dundee, Scotland. The data collected included age, sex, aetiology, month in which injury occurred, anatomical site of fracture, associated maxillofacial trauma and treatment modalities. The majority of fractures were sustained by males in the age group 20 to 29 years. Assault was the major cause of trauma followed by falls and road traffic accidents. The posterior body region was found to be the most common fracture site in the mandible. The level of such trauma has more than doubled, since a similar study was undertaken between the years 1961 to 1970.

p53 protein in odontogenic cysts: increased expression in some odontogenic keratocysts.

AIMS: To assess p53 protein expression in a range of odontogenic cysts arising in the mouth, including those of developmental and inflammatory origin. METHODS: p53 protein was identified using the polyclonal antibody CM-1, together with a standard immunoperoxidase technique. A total of 36 cystic lesions were examined, all of which were histologically benign. RESULTS: Expression of p53 protein was identified within the lining of five of 12 odontogenic keratocysts but was not detected in the other cystic lesions in the series. CONCLUSIONS: This is believed to be the first report that identifies increased expression of p53 protein in benign cystic epithelium. The increased expression of p53 protein in the nucleus is usually associated with malignant disease. These findings are relevant to the management of odontogenic keratocysts which have a tendency to recur, and also to Gorlin Goltz syndrome in which keratocysts and multiple basal cell carcinomas are features.

An overview of the cell cycle arrest protein, p21WAF1

p21, also known as WAF1, Cip1, Sdi1, Mda 6 and Cap20 is a cell cycle protein that regulates and can arrest the cell cycle in G1 or S phase (either dependent or independent of p53). Its role may be pivotal in many cell processes including differentiation and apoptosis. This brief overview provides a summary of its presently known functions and indicates areas for further research, particularly in relation to oral malignant disease. Greater understanding of its role may lead to therapeutic advances in the management of malignant disease.

Aetiology of oral cancer: alcohol

The effect of alcohol alone on the oral mucosa and its association with the development of oral cancer is difficult to establish, principally because alcohol consumption histories are difficult to verify, alter over time, both with respect to beverage type and quantity, and are frequently confounded by tobacco use. This review considers the various pathways by which alcohol may exert such an influence. Namely, due to topical exposure (e.g. direct effect on cell membranes, altered cell permeability, variation in enzymes that metabolise alcohol) and/or systemic effects (e.g. nutritional deficiency, immunological deficiency, disturbed liver function). Finally, the numerous papers that have sought to establish the relative risk for oral cancer in association with alcohol intake are reviewed.

Apoptosis, proliferation, and angiogenesis in oral tissues. Possible relevance to tumour progression

Experimental animal models have demonstrated that angiogenesis is essential for tumour progression, whilst sustained tumour growth requires a positive balance between tumour cell proliferation and cell death (apoptosis). The aim of this study was to determine the relative contribution of apoptosis, proliferation, and angiogenesis to disease progression in the oral mucosa. Histological sections of 47 archival specimens were examined; these included four groups of oral tissues: normal mucosa (n=12), moderate dysplasia (n=11) severe dysplasia (n=6), and squamous cell carcinoma (n=18). Apoptotic cells were visualized by in‐situ end‐labelling of DNA, proliferative cells by staining with Ki‐67 antibody, and blood vessels with von Willebrand factor (vWF) antibody. One‐way analysis of variance showed that indices of apoptosis (AI), proliferation (PI), and angiogenesis (vascularity) increased significantly with disease progression from normal oral mucosa, through dysplasia, to carcinoma (p<0.0001 for every index). The increase from normal mucosa to moderate dysplasia was significant for PI and vascularity, but not for AI. In contrast, the increase from dysplasia to carcinoma was significant for AI and vascularity, but not for PI. These data suggest that disease progression in the oral mucosa is accompanied by angiogenesis and increases in both epithelial proliferation and apoptosis. Net epithelial growth results from proliferation starting earlier and proceeding at a higher rate than apoptosis. Copyright

Detection of field change in oral cancer using oral exfoliative cytologic study

Four smears were taken from the normal buccal mucosa of 55 oral cancer patients and 76 cancer‐free patients. In each case, two were stained by the Papanicolaou method and two underwent Feulgen hydrolysis. Quantitative assessment of nuclear area (NA) and cytoplasmic area (CA) of the Papanicolaou smears was undertaken using a semiautomatic image analysis system. DNA profiles were assessed from the Feulgen smears using a Vickers M85 microdensitometer (Vickers Instruments, York, England) and were found to be diploid for all patients. Results were then analyzed with respect to those patients who took alcohol, tobacco, combination of alcohol and tobacco, and those who took neither. A significant reduction in CA for the oral cancer group (P equals 0.001) but no change in NA (P equals 0.74) was observed. A detailed analysis of alcohol and tobacco habits could identify no significant role for these two factors, in the reduction in cytoplasmic area. Such field change may prove to be of value in predicting the development of second malignant tumors.

OVEREXPRESSION OF p53 IN NORMAL ORAL MUCOSA OF ORAL CANCER PATIENTS DOES NOT NECESSARILY PREDICT FURTHER MALIGNANT DISEASE

Recent reports of p53 positivity in the normal mucosa of some head and neck cancer patients have been taken as evidence for field cancerization and hence a likelihood of the development of further tumours, yet few papers report the clinical significance of this finding through long‐term follow‐up. The immunohistochemical detection of p53 expression in clinically and histopathologically normal oral mucosa taken from the wound margin following excision of oral cancer was assessed using the polyclonal antibody CM1. Fresh frozen biopsies of normal oral mucosa and the corresponding tumour from 21 oral cancer patients and of normal mucosa from 25 non‐cancer patients were assessed for p53 overexpression. The ‘normal’ mucosa was positive in 12 of the oral cancer patients and one of the non‐cancer patients. Second malignant tumours were seen in patients from whom p53‐positive ‘normals’ and p53‐negative ‘normals’ were recorded. In five of the p53‐positive ‘normals’, the corresponding cancer was p53‐negative. In one case, where ‘normal’ mucosa was available from more than one site, one region was positive, whilst the other was negative. No obvious difference in age, tobacco use, or recurrence rate was seen between positive and negative cases. All patients who were still alive were reviewed for a minimum of 5 years. Using Fishers exact test, no statistically significant difference was found for the rate of second malignant tumours occurring in patients with p53‐positive compared with p53‐negative normal mucosa. Thus, the detection of p53 in normal mucosa did not necessarily predict a further tumour.

Evidence for field change in oral cancer based on cytokeratin expression.

It was hypothesised that one may be able to visualise field changes, which are proposed to exist around tumours, as alterations in keratin intermediate filament protein expression. Standard immunohistochemical analysis using a panel of monoclonal anti-keratin antibodies was applied to fresh tissue sections to look for subtle changes in epithelial differentiation not visible in H&E sections. Such changes were observed in clinically normal epithelium from oral cancer patients, involving primarily substantial expression of keratins K8/K7 (using CAM 5.2) in the basal cells of 12 out of 34 biopsies, and also a trend towards a reduction in the complexity of keratin differentiation. Monitoring such changes may prove to be a valuable adjunct to conventional H&E staining if found to have prognostic and diagnostic significance.