1. drtbalu1 Etiology of Head & Neck malignancies Dr. T. Balasubramanian

2. drtbalu2 Introduction Squamous cell carcinoma is the most common head and neck malignancy More than 90% of head and neck cancers are of squamous type These cancers are difficult to treat because of the proximity of vital structure like great vessels Early diagnosis will go a long way in improving the prognosis

3. drtbalu3 Common causative agents Tobacco Alcohol Polycyclic hydrocarbons Nitrosamines Viral infections (EB virus) Radioactive Polonium – 210 Canabis Wood dust (African mahogany)

4. drtbalu4 Smoking Tobacco plays an important role in the etiology of Head and neck cancers Concomittent use of tobacco and alcohol increases the risk of head and neck malignancy by 4 times Risk also increases proportionate to the number of cigarettes smoked per day Air processed dark tobacco has twice the risk when compared to light colored ones

5. drtbalu5 Tobacco Tobacco contains about 43 clearly demonstrable carcinogens Method of tobacco use is also relevent in the context of the subsite involved. Palatal malignancy is common in tobacco chewers while lung malignancies are common in smokers Common carcinogen found in cigarette include: Polycyclic hydrocarbons, Nitrosamines and radioacive polonium - 210

6. drtbalu6 Cannabis Cannabis smoking carries higher risk of head and neck malignancy than tobacco Cannabis contains larger quantities of coal tar and aromatic hydrocarbons than tobacco Cannabis is highly lipid soluble and hence permeates across tissue barriers.

7. drtbalu7 Role of alcohol Alcohol is not a carcinogen perse It potentiates the carcinogenic effects of smoking tobacco as it is an excellent solvent. It dissolves the carcinogens present in tobacco thereby facilitating tissue permeation of these substances It also affects the synthesis of retenoids in the body. These retinoids have cancer protective function

8. drtbalu8 Types of alcohol Type of alcohol consumed plays an important role in carcinogenesis Nitrosamine content of Beer is more than other alcoholic beverages. Wine contains resveratrol which is a potent cancer preventing agent. Red wine contains large amounts of Resveratrol and hence is very good for health

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11. drtbalu11 Role of viruses Human papilloma virus plays an important role These viruses can be classified into high risk, medium risk and low risk types High risk – types 16 & 18 Medium risk – types 31 & 33 Low risk – types 6 & 11 EB virus is another virus associated with head and neck malignancy (NPC)

12. drtbalu12 Adult vs Juvenile types of resp papilloma Adult respiratory papilloma is caused by low risk papilloma virus strain Juvenile respiratory papilloma is caused by high risk papilloma strain hence malignant transformation is common in this age group PCR studies have demonstrated high risk strain of papilloma viruses in head and neck malignant tumors

13. drtbalu13 Sunlight Over exposure to sunlight have been known to cause malignant tumors UV light component of sunlight is the culprit Melanoma / squamous cell caricinoma of skin and lips can be caused by UV radiations from sunlight.

14. drtbalu14 Occupational Workers working in nickel / chromium refining factories Workers in Asbestos factories Workers in wood industry using African Mahogany type of wood

15. drtbalu15 Dietary factors Patterson Brown kelly syndrome Salted fish diet & Nasopharyngeal carcinoma ? Laryngopharyngeal reflux

16. drtbalu16 Genetic factors Genetically caused loss of control over cell production & cell death Mutations involving protooncogenes Inactivation of tumor suppressor genes Mutations could be point mutations, deletions or amplification of segments of DNA Mutations causing failure of detoxification of carcinogens

17. drtbalu17 Role of polymorphism Polymorphism is presence of different versions of same enzyme in different individuals These enzymes are involved in the metabolism of carcinogens N acetyl transferase & Gluthathione s transferase are examples of enzymes showing polymorphism

18. drtbalu18 Radiation exposure Radiation exposure is known to cause point mutations These mutations inturn can predispose to head and neck malignancy Previously irradiation was used to treat TB cervical nodes. These patients later became prone for head & neck malignancies

19. drtbalu19 Thank you