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| TOBACCO ROLE IN
THE ETIOLOGY OF ORAL CANCER, PERIODONTAL DISEASE AND OTHER ORAL LESIONS |
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Lecturer Dr. Heddie O. Sedano, DDS, Dr. Odont |
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Tobacco usage either smoked (cigarette and pipe) or chewed and or dipped, has become one of the larger health problems world wide to the degree that is considered by some a world epidemic. Additional consequences to tobacco usage are, among others:
BRIEF
HISTORICAL REVIEW Tobacco was used by American aborigines mixed with spices and other plants, this mixture was inserted into a primitive pipe that they called tobaga and then smoked. Occasionally tobacco was also inhaled through the nose by means of a Y-shaped pipe. These aborigines used tobacco for medicinal and religious purposes. Aztecs chewed tobacco leaves to treat tooth aches and aborigines of North America mixed tobacco leaves with sea shells and lime for the same purpose. This combination induced marked teeth abrasion because of the sea shells. Poisonous snakes were numbed with tobacco smoke so that they could be manipulated during religious rites. Inhaled tobacco was also used to induce hallucinations, apparently these Indians used the tobacco species nicotiana rustica which has a high content of nicotine as well as other alkaloids as opposed to the species used presently, nicotiana tabacum, in the production of cigarettes and other forms of tobacco. According to some historians the aborigines also believed that tobacco could cure stomach ailments as well as headaches. American Indians rubbed tobacco juice on the wound produced by a snake bite in order to treat it. Historical reports are not in agreement as to who was the first to introduce tobacco to Europe. Some maintain that Columbus brought seeds back after his first trip while others assume that Juan Ponce de León was the first to bring tobacco seeds to Europe in 1496 at his return from America on the second trip of Columbus. It is also stated that Columbus might have been the first European to oppose the use of tobacco because it is said that he admonished his sailors for engaging in the practice of inhaling tobacco smoke imitating the American Natives. Posterior explorers, especially the Portuguese, possibly recognized the potential of this "holy herb" and tobacco was fully introduced to Europe as a medicinal plant. Sir Walter Raleigh brought tobacco seeds to England after his second trip to America in 1565. The French ambassador to Lisbon, Jean Nicot de Villemain, obtained dried tobacco leaves and seeds and sent them to the queen mother in France, Catherine of Medici, exalting the medical capabilities of tobacco. Jean Nicot received the "ill honor" of having the botanical name of this plant named after him, nicotiana tabacum, as well as the main alkaloid: nicotine. The tobacco plant is a member of the nightshade family (Solanaceae family). There is no total agreement on the origin of the word tobacco, the most likely derivation is from the name of the pipe used by the Indians, either tobaga or tobaca. Some historians claim the derivation stems from the state of Tabasco in Mexico or the island of Tobago in the Caribbean, both of which are large producers of tobacco, but these are most unlikely origins of the word. GENERAL
STATISTICS Thirty percent of all cancer deaths and over 80% of lung cancer deaths are caused by tobacco. The lung cancer death rate for men was 4.9 per 100,000 in 1930 and it has increased to 75.6 per 100,000 in the decade of 1990. Ninety-two percent of oral squamous cell carcinoma (OSCC) in men and 61% of OSCC in women are attributable to tobacco usage. The Centers for Disease Control and Prevention in 1999 reported that among high school male students smokeless tobacco was used by: 20% of white males, 6% of Hispanic males and 4% of Black males. The same report states that 48 million US adults smoke cigarettes and of those half will die of smoking related disease if they continue smoking. Hoffmann and Djordjevic in 1997 reported that the habit of chewing tobacco had declined by 30.6%, but that snuff use had increased, by almost 52%. The increase was due, primarily, to the use of oral snuff by teenage and adolescent males. Chewing of tobacco represents a risk for oral cancer. Snuff dipping is considered as one of the etiological factors of OSCC of the cheek, gingiva, and pharynx. Presently 430,000 deaths each year are related to tobacco. Exposure to environmental tobacco smoke (ETS) is a well known fact, it has been reported that 87.9% of children and adult non-users of tobacco had detectable serum levels of the nicotine metabolite "cotinine" as a result to tobacco smoke exposure. The excess risk to develop lung cancer for women that do not smoke but which are exposed to ETS, has been estimated as 1 to 2% of that in smokers. Moderate to severe periodontitis is found in 25.7% of cigarette smokers, 20.2% of former cigarette smokers and 13.1% of non-smokers. The difference in prevalence of periodontal disease for these three groups is statistically significant. The prevalence of moderate and severe periodontitis in current or former cigar/pipe smokers is estimated at 17.6%. TOBACCO
AND PRECANCEROUS LESIONS
FIGURE 1. A particular form of leukoplakia known as proliferative verrucous leukoplakia (PVL) also can be associated to tobacco usage. Around 1/3 of PLV are diagnosed in heavy smokers. PVL has a higher risk of malignant transformation than the most common non-verrucous leukoplakias. FIGURE 2. Erythroplasia is a red lesion of the oral mucosa with no apparent cause. Erythroplasia also should be carefully evaluated especially if there is history of tobacco usage. Erythroleukoplakia is a frequent combination of white and red lesions. These combined lesions have four times the potential for malignant transformation than that of a plain white or red lesion and because of this increased risk invariably they should be biopsied.
FIGURE 3. TOBACCO
AND ORAL CARCINOMA A follow-up study of more than 5 years of 403 oral cancer patients at the University of California in San Francisco (UCSF), found that 72% of those patients were smokers and 50% smoked more than one pack a day. A second study of 595 patients by the same group at UCSF indicated that an average of 82% of patients with oral cancer in: tongue, oropharynx, floor of the mouth, gingiva, buccal mucosa, lips and hard palate were tobacco users. The highest prevalence being the floor of the mouth with 90% and the lowest the hard palate with 55%. FIGURE 4. Oral squamous cell carcinoma is the most frequent form of cancer among men and the third most frequent among women in India and Pakistan. These carcinomas are associated to the habit of paan and also to reverse smoking. Paan is a quid of betel leaf containing areca nut, lime, condiments, sweeteners, and sometimes tobacco. This quid is kept in the mouth and chewed. Submucous fibrosis is another intraoral disease related to the habit of paan which also predisposes to oral carcinoma.
FIGURE 5. FIGURE 6.
FIGURE 7. P53 is a "tumor suppressor gene" located on the short arm of chromosome 17 (17p13.1). P53 has a basic function in the cellular cycle control and subsequently in the induction of neoplastic processes. The protein p53, coded by the gene with the same name, regulates apoptosis. Apoptosis is an irreversible process that conduces to natural cell death. Mutations in p53 eventuate in cessation of apoptosis which allow for the growth and development of abnormal cells. This over expression of the mutated p53, in the oral cavity, seems to be directly related to tobacco, alcohol and arica nut (betel nut) usage. P16 is another tumor suppressor gene located on the short arm of chromosome 9 (9p21-23). Genetic mutations at the level of p16 have been reported in a subset of chewing tobacco-induced oral cancers. TOBACCO
AND PERIODONTAL DISEASE Various reports have documented that after a period of several years of follow-up, habitual smokers have an increased frequency of periodontal disease versus decreased frequencies in non-smokers and former smokers. These differences were statistically significant. Periodontal bone height has been shown to be significantly reduced in habitual smokers and former smokers as opposed to that of non-smokers after adjusting for oral hygiene and age. Even when plaque formation is kept to a minimum, smokers present deeper and greater number of periodontal pockets than non-smokers. The alveolar bone loss results in a two fold prevalence of furcation in smokers over that in non-smokers, as documented by radiographs. Statistical studies have shown that the severity of periodontal disease increases with the number of cigarettes smoked and the number of years that a patient has smoked. Periodontally, smokers often have advanced attachment and bone loss associated with relatively healthy appearing gingival tissues. It is especially important to carefully probe all teeth so that these defects are identified. Serum levels of cotinine seem to correlate with the degree of attachment loss, pocket depth and alveolar bone loss. Periodontal health status remains stable in former smokers and non-smokers, thus suggesting that abandoning the habit is beneficial to the periodontium. The impact of cigarette smoking on the periodontal health has also been documented in young patients (19 to 30 years old), in that age group smokers have almost four times the chance to develop periodontitis than individuals of the same age that never had smoked. TOBACCO
AND WOUND HEALING Additionally nicotine induces platelet aggregation with increased blood viscosity, this phenomenon favors the formation of microclots leading to capillary embolism and ischemia of the affected tissues. Vasoconstriction is another by-product of nicotine due to the release of catecholamines. Catecholamines induce the formation of chalones which interfere with normal wound healing and epithelialization. Carbon monoxide has a greater capability for binding to hemoglobin than that of oxygen, thus reducing the amount of oxygen binding to hemoglobin and diminishing the distribution of oxygen to tissues with consequent cellular hypoxia and interference with normal wound healing. Hydrogen cyanide also participates in the alteration of oxygen metabolism and distribution, further delaying wound healing and epithelialization. These facts can be easily extrapolated to the regenerative process and epithelial re-attachment following periodontal surgery. Therefore, it is imperative that smokers that must undergo surgical procedures be advised to stop smoking for at least 12 waking hours prior to surgery. That is the time needed for the carbon monoxide to be completely released from hemoglobin. Likewise those patients must be advised to abstain from smoking during the entire post-operative period to improve their deficient wound healing. OTHER
ORAL LESIONS ASSOCIATED WITH TOBACCO USAGE ACUTE NECROTIZING ULCERATIVE
GINGIVOSTOMATITIS (ANUG) Pindborg in 1947 was the first to scientifically establish a link between smoking and the development of ANUG in young Danish recruits. ANUG has its peak incidence in winter in patients in their early twenties, with a marked predilection for males. Children are rarely if ever affected. The initial lesions--swollen, red papillae--generally occur in the mandibular molar area. However, other gingival areas may be affected. The edematous gingiva rapidly undergoes ulceration, producing characteristic, punched-out erosions of the dental papillae. The free gingiva becomes covered with a yellowish-gray pseudomembrane with a red halo. Fetor ex ore (halitosis) and excessive salivation are marked, and patients frequently complain of a metallic taste. Pain, tenderness, and bleeding lead to inability to eat. Regional lymphadenitis is usually marked. Low-grade fever, headache, and malaise are common. ANUG may involve the oropharynx or other areas of the oral mucosa if the patient's resistance is low or the condition is not treated. In such patients, tachycardia, leukocytosis and gastrointestinal disturbances may occur. FIGURE 8. ANUG has a rapid onset. If treated, it generally subsides within 48 hours. Spontaneous remission and healing also may occur in 1 to 3 weeks. Recurrence of the disease is observed with high frequency, generally owing to retention of micro-organisms and debris in the punched-out areas of destruction, as well as continued smoking. Occasionally, considerable tissue destruction occurs, producing marked recession of the interdental papillae and of the marginal gingiva. Bone sequestration may occur. Rarely, complications such as noma, septicemia, and even death have occurred. Healing time and the effectiveness of treatments are delayed in smokers. NICOTINE STOMATITIS is also known as smoker's palate and it is characterized by marked hyperkeratosis of the hard palate and secondary inflammation of underlying structures. It is seen in a considerable number of heavy tobacco smokers and is independent of the type of smoking habit. The great majority of cases are seen in males with a mean age of 50 years. Most frequently affected are pipe smokers, followed by cigarette smokers, and, far behind, cigar smokers. The initial manifestation of the condition is marked erythema of the palate. This is followed by numerous red papular elevations around the opening of the excretory ducts of the palatal minor salivary glands. These elevations, of various sizes, soon become covered with a white to gray, generally uniform layer of either ortho- or parakeratin formation. The lesion progressively extends to the rest of the hard palate. Occasionally, whitening can also be seen in the soft palate. With time, cracks and fissures appear in the palate, which then presents the late clinical picture of the condition--i.e., elevated keratinized nodules of various sizes with a central, small, red, rounded point, representing the ductal opening of a minor salivary gland, the nodules being separated by the small fissures. The entire palatal surface, then, presents a rough, irregular appearance. FIGURE 9. The thickness and the general clinical appearance of the lesion vary according to amount of tobacco used and the age of the lesion. Some authors had considered that this condition might possibly become malignant. A histologic survey, performed by the present author, in 66 cases of nicotinic palatal leukokeratosis showed that only one case presented epithelial histologic changes compatible with the diagnosis of premalignant epithelial dysplasia. The condition presents such a typical clinical appearance that differential diagnosis is essentially unnecessary. Nevertheless, hyperkeratosis of other causes could be considered. Reverse smoking, a frequent practice in some areas of India and the Philippines, also induces palatal changes but with more pronounced clinical manifestations and early malignant transformation. Biopsy should be performed in order to eliminate the possibility of malignant transformation. It is assumed that remission occurs when patients abandon the smoking habit. SNUFF POUCH (SP) is a form of hyperkeratosis with various degrees of clinical manifestation. SP develops on those mucosal sites where the tobacco is held. The causal agents of SP are considered to be the nitrosamines and hydrocarbons contained in tobacco. Prolonged use of this habit may conduce to the development of a squamous cell carcinoma (see above) due to the carcinogenic potential of those components. SP has been classified clinically into three different degrees. Degree 1 SP has the color of normal mucosa presenting a minor degree of superficial early wrinkling, the wrinkles disappear when the lesion is stretched. Degree 2 SP is a combination of white-gray and reddish areas with moderate wrinkles, neither wrinkles nor colors disappear when the lesion is stretched.
FIGURE 10. These lesions will slowly disappear after cessation of the habit. Degree 3 SP presents a color similar to that seen in degree 2 (white-gray and reddish) but the mucosa has pronounced thick wrinkles which do not disappear when stretched. The longer the habit the higher the degree. Cessation of the habit, especially if it is not of long duration, eventuates in disappearance of the lesion. FIGURE 11. HAIRY TONGUE is an elongation of the filiform papillae which become pigmented to varying degrees by products of some bacteria, fungi, antibiotic therapy, medications containing bismuth or tobacco. The dorsum of the tongue is symmetrically covered by a thick coat of enlarged hyperkeratinized filiform papillae resembling hairs. These may be black, brown or yellow. Hence, the different names used, i.e. black hairy tongue. When associated to smoking the color varies from dark brown to black. The only complication may be occasional gagging if the papillae are grossly enlarged. The pigmentation of the papillae will disappear after cessation of smoking.
FIGURE 12. SMOKING ASSOCIATED MELANOSIS of the oral mucosas can develop especially on the gingival and palatal mucosas. Some particles in the tobacco smoke induce stimulation of the mucosal melanoblasts resulting in hyperpigmentation which imitates the physiologic gingival pigmentation. This pigmentation tends to slowly disappear over a period of several months after cessation of smoking. TEETH CHANGES ASSOCIATED
WITH SMOKING
FIGURE 13. Teeth abrasion is seen in those teeth that a pipe smoker uses to support the pipe. The loss of enamel and partially of dentin, can be so severe as to produce an open bite at the level of the affected teeth. Abrasion is also seen in patients that chew tobacco and betel nut chewers.
REVERSE SMOKING fortunately is a habit seldom seen in USA but is frequent in India and the Philippines especially among women which held the lit end of a cigarette inside their mouth, generally, while washing clothes by the river. The combination of heat and the carcinogenic potential of cigarette smoke induce the formation of a variety of palatal lesions including: leukoplakia, erythroleukoplakia, ulcerations and squamous cell carcinoma. CONCLUSIONS
Albandar JM et al. Cigar, pipe, and cigarette smoking as risk factors for periodontal disease and tooth loss. J Periodontol 2000; 71:1874-81. Anderson KE et al. Metabolites of a tobacco-specific lung carcinogen in nonsmoking women exposed to environmental tobacco smoke. J Nat Cancer Inst 2001;93:378-81. Bergstrom J et al. A 10-year prospective study of tobacco smoking and periodontal health. J Periodontol 2000;71:1338-47. Campanile G et al. Cigarrete smoking, wound healing and face lift. Clinics in Dermatol 1998;16:575-8. Cox SC. Walker DM. Oral submucous fibrosis. A review. Australian Dent J 1996;41:294-9. Craig S, Rees TD. The effects of smoking on experimental skin flaps in hamsters. Plast Reconstr Surg 1985;75:842-6. Greer RO Jr, Poulson TC: Oral tissue alterations associated with the use of smokeless tobacco by teenagers. I. Clinical findings. Oral Surg 1983; 56:275-284 Hart GT et al. Tobacco use and dental disease. J Tennessee Dent Ass 1995;75:25-7. Hoffmann D; Djordjevic MV. Chemical composition and carcinogenicity of smokeless tobacco. Advances Dent Research 1997;11:322-9. Mahale A, Saranath D. Microsatellite alterations on chromosome 9 in chewing tobacco-induced oral squamous cell carcinomas from India. Oral Oncol 2000;36:199-206. Meraw SJ et al. Cigarrete smoking and oral lesions other than cancer. Clinics in Dermatol 1998;16:625-31. Offenbacher S, Weathers DR: Effects of smokeless tobacco on the periodontal, mucosal and caries status of adolescent males. J Oral Pathol 1985; 14:169-181. Pindborg JJ. Tobacco and gingivitis: I. Statistical examination of the significance of tobacco in the development of ulceromembranous gingivitis and in the formation of calculus. J Dent Res 1947;26-261-4. Pindborg JJ. Tobacco and gingivitis: II. Correlation between consumption of tobacco, ulceromembranous gingivitis and calculus. J Dent Res 1949;28:460-3. Position paper: tobacco use and the periodontal patient. Research, Science and Therapy Committee of the American Academy of Periodontology. J Periodontol 1999;70:1419-27. Ralhan R et al. Induction of MDM2-P2 transcripts correlates with stabilized wild-type p53 in betel- and tobacco-related human oral cancer. Amer J Pathol 2000;157:587-96. Scully C et al. Genetic aberrations in oral or head and neck squamous cell carcinoma (SCCHN): 1. Carcinogen metabolism, DNA repair and cell cycle control. Oral Oncol 2000;36:256-63. Silverman S. Oral Cancer 4th Edit. Amer. Cancer Soc. B.C.Decker Inc. 1998, Chapter 2. Straten MV et al. Tobacco Use and Skin Disease. South Med J 2001;94:621-634 Tobacco use--United States, 1900-1999. Mmwr. Morbidity and Mortality Weekly Repor 1999;48:986-93. Walsh PM, Epstein JB. The oral effects of smokeless tobacco. J Canadian Dent Ass 2000;66:22-5. |
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