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Buccal Mucosal Cancer
 

Buccal Mucosal Cancer

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    Buccal Mucosal Cancer Buccal Mucosal Cancer Document Transcript

    • BUCCAL MUCOSAL CANCER Dr.Anil Haripriya
    • Epidemiological studies have documented a high incidence of oral cancer in India and some south-east Asian countries21. According to the Indian Council of Medical Research about 200,000 cases of cancer of the oral cavity are seen every year in India. Estimates based on weighted averages of data from Bangalore, Mumbai, Bhopal, Chennai, and Delhi show that carcinoma of the oral cavity has an incidence of 4.0% of all malignancies in males and 3.5%of all malignancies in females (Tables 1 and 2). Due to its relatively prolonged course, it is estimated that its prevalence is around 12% of all malignancies in males and 10 % of all malignancies in females. The age-adjusted incidence rate of oral cavity carcinoma is 25 per 100,000 in India. Table 1 : Incidence of Buccal Mucosa Cancer (% of all malignancies) Registry Males Females M:F ratio Delhi 1.49 0.58 2.6 Bhopal 6.72 3.0 2.24 Chennai 6.05 4.48 1.25 Bangalore 1.86 6.57 0.28 Mumbai 3.66 2.65 1.6 Worldwide,
    • as well as in India there has been a steady increase in the incidence of cancer of the oral cavity. The male to female ratios are decreasing worldwide (Table 3) probably due to the rise in use of tobacco products and alcohol by women. In India tobacco related cancers account for almost half of the total cancers in men and one fourth in women. Oral cancer accounts for a third of these with 90% being tobacco chewers. The high incidence of this cancer in Indian women is probably because the prevalence of tobacco chewing is more or less equal between the sexes13. The high incidence of buccal mucosal cancer in India is also probably a consequence of tobacco chewing and usage of a ‘quid’. Studies have reported a high incidence of this cancer in people of Indian descent settled in South Africa6 and in Malaysia22. Even in these populations, the incidence among females of Indian origin is much higher than the native populations. Whether this is a reflection of ingrained habits and customs or due to genetic susceptibility is not clear. RISK FACTORS
    • Tobacco and alcohol have consistently been associated with cancers of the oral cavity. Buccal mucosal cancer in India is associated predominantly with the habit of tobacco chewing especially the type endemic to this country. Tobacco Consumption in India : Only 20% of the tobacco consumed in India is in the form of cigarettes. Bidis account for 40% of tobacco consumption with the rest divided among chewing tobacco, pan masala, snuff, hookah, hookli, chutta, dhumti, and other tobacco mixtures featuring ingredients such as areca nut. Buccal mucosal cancer is related to the use of smokeless tobacco. Smokeless tobacco is in common usage in this country in various forms17. Pan chewing is widely practiced in India. Also known as betel quid, it consists of tobacco, areca nuts, and slaked lime wrapped in a leaf. Various types of tobacco are used in pan. Like zarda, pattiwala, kiwam, mishri and pills. Some variants of pan include pan masala, mainpuri, and mawa. Khaini is a mixture of tobacco and slaked lime which is left in the lower gingivolabial sulcus for a prolonged time19. Studies have shown that keeping a tobacco quid in the cheek pouch
    • overnight increases the risk of buccal mucosal cancer4,5,16. Also the addition of lime increases the carcinogenicity of tobacco by alkalinisation which leads to differences in the composition & concentration of mutagens from tobacco17. Some of these mutagens that have been identified positively are tobacco specific N-nitrosamine (TSNA), N’- nitrosonorcotine (NNN) and 4(methylnitrosamino)-1-(3- pyridyl)-1-butanone (NNK) being the most important7. Also, reactive oxygen species and OH` radical formed from polyphenolic betel quid ingredients and lime at alkaline pH have been implicated as the agents responsible for DNA and tissue damage. These agents are formed in vitro in the presence of extracts of areca nut and catechu, transition metal ions such as Cu 2+ and Fe 2+ and lime or sodium carbonate15. Table 2 : Buccal mucosa cancer - Cumulative risk (%)
    • Registry Sex 0-14 y 15-34 35-69 0-64 y 0-74 y y y Delhi M 0.00 0.00 0.22 0.19 0.30 F 0.00 0.01 0.15 0.12 0.16 Bhopal M 0.00 0.03 0.86 0.55 1.03 F 0.00 0.00 0.60 0.49 0.60 Chennai M 0.00 0.00 0.60 0.44 0.74 F 0.00 0.02 0.59 0.44 0.74 Mumbai M 0.00 0.00 0.35 0.25 0.42 F 0.00 0.00 0.25 0.18 0.31 Bangalore M 0.00 0.00 0.19 0.15 0.25 F 0.00 0.01 0.74 0.58 0.86 Table 3 : Cancer of the lip and oral cavity in other regions of the world Country Incidence (per M:F 100000) ratio England & 2.8 1.7 Wales South 8.06 4.1 Africa Norway 2.1 1.2 U.S.A. 3.1 2.0 India 25.0 1.6
    • Human Papilloma Virus : HPV has been consistently isolated in an abnormally high percentage of Indian patients of cancer of the oral cavity. The habit of betel chewing is thought to play a role in the etiology of this disease. The prevalences of HPV-6, HPV-11, HPV-16 and HPV-18 were 13%, 20%, 42% and 47% respectively. Though these studies show that HPV has probably a role in the mutagenecity of betel, the evidence at present is purely circumstantial2,16,21. Genetic Alterations: Alterations in p53 and p16 are common in tumours from the West (47%) but are uncommon in the East (7%). The tumours from India and South Asia are characterised by the involvement of ras oncogenes, including mutations loss of heterozygosity (H-ras), and amplification (K- and N-ras), events which are uncommon in the West. There is a possibility that these genetic differences reflect aetiology and/or ethnic origin4,8,18. Nutritional Status : Various studies have shown that modulators of epithelial differentiation like vitamins A, E and beta carotene are protective for oral cancers and are capable
    • of reversing premalignant changes like leukoplakia3,20. Submucous Fibrosis : Oral submucous fibrosis is a precancerous condition of the mouth that is strongly associated with chewing areca nuts. It is reported to occur more frequently among women rather than men. Aetiologies that have been proposed include stimulation of collagen production and decreased activity of collagenase due to various components of areca nut such as arecoline and tannins. Symptoms of submucous fibrosis include localized burning and intolerance to spicy food, followed by blanching and ulceration of the mucosa and the formation of characteristic fibrous bands These bands form bilaterally, initially in the fauces and then in the buccal ands labial areas. As the disease progresses the bands on either side meet on the floor and the roof of the mouth forming a fibrous ring. The diagnosis of this condition is made on clinical grounds and there are no reports of staging it by severity though a histological classification has been proposed12. PATHOLOGY
    • Buccal mucosal cancer is almost invariably squamous cell carcinoma. Depending on the degree of keratinization, it is divided into well differentiated (>75% keratinized), moderately differentiated (25-50% keratinized) and poorly differentiated (<25% keratinization)10. Probably as a consequence of HPV having a role in aetiology of buccal mucosal cancer, a large proportion of Indian patients have verrucous carcinoma2,16,21. Verrucous carcinoma, also known as Ackerman’s tumour is well differentiated and is characterized by a cauliflower like exophytic growth with deep papillary projections and a grey- white surface. These tumours are slow growing, metastasize late and offer a better prognosis. They may however dedifferentiate and metastasize following irradiation10. CLINICAL FEATURES Patients of buccal mucosal cancer in India typically belong to the lower socio-economic strata. They are also younger than patients in the West by about a decade. These patients are invariably tobacco or pan chewers with poor oral hygiene and staining of teeth. Often, submucous fibrosis is also
    • present. Other premalignant lesions such as leukoplakia or erythroplakia may also be seen alone or in conjunction. The tumours are seen commonly in the lower gingivolabial sulcus adjacent to the site where the quid of betel or tobacco is kept in the mouth1,2. Common early symptoms are pain, itching, swelling, dull sensation and colour change. These symptoms are invariably tolerated by the patients, signifying a type of person who neglects personal care. Thus these patients mostly present late in the course of their illness with advanced lesions1 and features like large primary lesion, trismus, odynophagia, tethering of the tongue, oro-cutaneous fistula, satellite nodules, and lymph node enlargement. Lymph nodes when enlarged are of the submandibular group. The upper deep cervical nodes are usually not involved10. Conclusion Though traditionally, and in western textbooks, buccal mucosal cancer has been clubbed with other oral cancer, it is in fact a very different entity in terms of epidemiology, aetiology, pathology and clinical features. Little has been
    • written on buccal mucosal cancer in literature and it is for Indian researchers to study and throw new light on this common cancer about which knowledge is so inadequate. What is evident about the aetiology must form the basis of an intensive education and awareness campaign to affect a decrease in the rising incidence of this preventable cancer. .