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Etiology of Head and neck malignancy


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Etiology of Head and neck malignancy

  1. 1. Etiology of Head & Neck malignancies Dr. T. Balasubramanian
  2. 2. Introduction <ul><li>Squamous cell carcinoma is the most common head and neck malignancy
  3. 3. More than 90% of head and neck cancers are of squamous type
  4. 4. These cancers are difficult to treat because of the proximity of vital structure like great vessels
  5. 5. Early diagnosis will go a long way in improving the prognosis </li></ul>
  6. 6. Common causative agents <ul><li>Tobacco
  7. 7. Alcohol
  8. 8. Polycyclic hydrocarbons
  9. 9. Nitrosamines
  10. 10. Viral infections (EB virus)
  11. 11. Radioactive Polonium – 210
  12. 12. Canabis
  13. 13. Wood dust (African mahogany) </li></ul>
  14. 14. Smoking <ul><li>Tobacco plays an important role in the etiology of Head and neck cancers
  15. 15. Concomittent use of tobacco and alcohol increases the risk of head and neck malignancy by 4 times
  16. 16. Risk also increases proportionate to the number of cigarettes smoked per day
  17. 17. Air processed dark tobacco has twice the risk when compared to light colored ones </li></ul>
  18. 18. Tobacco <ul><li>Tobacco contains about 43 clearly demonstrable carcinogens
  19. 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. 20. Common carcinogen found in cigarette include: Polycyclic hydrocarbons, Nitrosamines and radioacive polonium - 210 </li></ul>
  21. 21. Cannabis <ul><li>Cannabis smoking carries higher risk of head and neck malignancy than tobacco
  22. 22. Cannabis contains larger quantities of coal tar and aromatic hydrocarbons than tobacco
  23. 23. Cannabis is highly lipid soluble and hence permeates across tissue barriers. </li></ul>
  24. 24. Role of alcohol <ul><li>Alcohol is not a carcinogen perse
  25. 25. It potentiates the carcinogenic effects of smoking tobacco as it is an excellent solvent.
  26. 26. It dissolves the carcinogens present in tobacco thereby facilitating tissue permeation of these substances
  27. 27. It also affects the synthesis of retenoids in the body. These retinoids have cancer protective function </li></ul>
  28. 28. Types of alcohol <ul><li>Type of alcohol consumed plays an important role in carcinogenesis
  29. 29. Nitrosamine content of Beer is more than other alcoholic beverages.
  30. 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 </li></ul>
  31. 33. Role of viruses <ul><li>Human papilloma virus plays an important role
  32. 34. These viruses can be classified into high risk, medium risk and low risk types
  33. 35. High risk – types 16 & 18
  34. 36. Medium risk – types 31 & 33
  35. 37. Low risk – types 6 & 11
  36. 38. EB virus is another virus associated with head and neck malignancy (NPC) </li></ul>
  37. 39. Adult vs Juvenile types of resp papilloma <ul><li>Adult respiratory papilloma is caused by low risk papilloma virus strain
  38. 40. Juvenile respiratory papilloma is caused by high risk papilloma strain hence malignant transformation is common in this age group
  39. 41. PCR studies have demonstrated high risk strain of papilloma viruses in head and neck malignant tumors </li></ul>
  40. 42. Sunlight <ul><li>Over exposure to sunlight have been known to cause malignant tumors
  41. 43. UV light component of sunlight is the culprit
  42. 44. Melanoma / squamous cell caricinoma of skin and lips can be caused by UV radiations from sunlight. </li></ul>
  43. 45. Occupational <ul><li>Workers working in nickel / chromium refining factories
  44. 46. Workers in Asbestos factories
  45. 47. Workers in wood industry using African Mahogany type of wood </li></ul>
  46. 48. Dietary factors <ul><li>Patterson Brown kelly syndrome
  47. 49. Salted fish diet & Nasopharyngeal carcinoma
  48. 50. ? Laryngopharyngeal reflux </li></ul>
  49. 51. Genetic factors <ul><li>Genetically caused loss of control over cell production & cell death
  50. 52. Mutations involving protooncogenes
  51. 53. Inactivation of tumor suppressor genes
  52. 54. Mutations could be point mutations, deletions or amplification of segments of DNA
  53. 55. Mutations causing failure of detoxification of carcinogens </li></ul>
  54. 56. Role of polymorphism <ul><li>Polymorphism is presence of different versions of same enzyme in different individuals
  55. 57. These enzymes are involved in the metabolism of carcinogens
  56. 58. N acetyl transferase & Gluthathione s transferase are examples of enzymes showing polymorphism </li></ul>
  57. 59. Radiation exposure <ul><li>Radiation exposure is known to cause point mutations
  58. 60. These mutations inturn can predispose to head and neck malignancy
  59. 61. Previously irradiation was used to treat TB cervical nodes. These patients later became prone for head & neck malignancies </li></ul>
  60. 62. Thank you