Squamous cell carcinoma is the most common head and neck malignancy, comprising over 90% of cases. Tobacco and alcohol are the most important causative agents, with risk increasing fourfold when used together. Tobacco contains over 40 known carcinogens like polycyclic hydrocarbons and nitrosamines. Cannabis smoking carries an even higher risk due to larger amounts of tar and aromatic hydrocarbons. While alcohol alone is not carcinogenic, it increases the risk from tobacco by facilitating tissue permeation of carcinogens. Viruses like HPV also contribute, with high-risk strains associated with malignant transformation. Prolonged sun exposure increases melanoma and lip cancer risk due to UV radiation. Occupational exposures like nickel, chromium,

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

3. More than 90% of head and neck cancers are of squamous type

4. These cancers are difficult to treat because of the proximity of vital structure like great vessels

5. Early diagnosis will go a long way in improving the prognosis

7. Alcohol

8. Polycyclic hydrocarbons

9. Nitrosamines

10. Viral infections (EB virus)

11. Radioactive Polonium – 210

12. Canabis

13. Wood dust (African mahogany)

15. Concomittent use of tobacco and alcohol increases the risk of head and neck malignancy by 4 times

16. Risk also increases proportionate to the number of cigarettes smoked per day

17. Air processed dark tobacco has twice the risk when compared to light colored ones

19. 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

20. Common carcinogen found in cigarette include: Polycyclic hydrocarbons, Nitrosamines and radioacive polonium - 210

22. Cannabis contains larger quantities of coal tar and aromatic hydrocarbons than tobacco

23. Cannabis is highly lipid soluble and hence permeates across tissue barriers.

25. It potentiates the carcinogenic effects of smoking tobacco as it is an excellent solvent.

26. It dissolves the carcinogens present in tobacco thereby facilitating tissue permeation of these substances

27. It also affects the synthesis of retenoids in the body. These retinoids have cancer protective function

29. Nitrosamine content of Beer is more than other alcoholic beverages.

30. Wine contains resveratrol which is a potent cancer preventing agent. Red wine contains large amounts of Resveratrol and hence is very good for health

34. These viruses can be classified into high risk, medium risk and low risk types

35. High risk – types 16 & 18

36. Medium risk – types 31 & 33

37. Low risk – types 6 & 11

38. EB virus is another virus associated with head and neck malignancy (NPC)

40. Juvenile respiratory papilloma is caused by high risk papilloma strain hence malignant transformation is common in this age group

41. PCR studies have demonstrated high risk strain of papilloma viruses in head and neck malignant tumors

43. UV light component of sunlight is the culprit

44. Melanoma / squamous cell caricinoma of skin and lips can be caused by UV radiations from sunlight.

46. Workers in Asbestos factories

47. Workers in wood industry using African Mahogany type of wood

49. Salted fish diet & Nasopharyngeal carcinoma

50. ? Laryngopharyngeal reflux

52. Mutations involving protooncogenes

53. Inactivation of tumor suppressor genes

54. Mutations could be point mutations, deletions or amplification of segments of DNA

55. Mutations causing failure of detoxification of carcinogens

57. These enzymes are involved in the metabolism of carcinogens

58. N acetyl transferase & Gluthathione s transferase are examples of enzymes showing polymorphism

60. These mutations inturn can predispose to head and neck malignancy

61. Previously irradiation was used to treat TB cervical nodes. These patients later became prone for head & neck malignancies

62. Thank you