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Etiology of Head and neck malignancy
 

Etiology of Head and neck malignancy

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    Etiology of Head and neck malignancy Etiology of Head and neck malignancy Presentation Transcript

    • Etiology of Head & Neck malignancies Dr. T. Balasubramanian
    • 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
    • Common causative agents
      • Tobacco
      • Alcohol
      • Polycyclic hydrocarbons
      • Nitrosamines
      • Viral infections (EB virus)
      • Radioactive Polonium – 210
      • Canabis
      • Wood dust (African mahogany)
    • 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
    • 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
    • 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.
    • 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
    • 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
    •  
    •  
    • 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)
    • 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
    • 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.
    • Occupational
      • Workers working in nickel / chromium refining factories
      • Workers in Asbestos factories
      • Workers in wood industry using African Mahogany type of wood
    • Dietary factors
      • Patterson Brown kelly syndrome
      • Salted fish diet & Nasopharyngeal carcinoma
      • ? Laryngopharyngeal reflux
    • 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
    • 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
    • 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
    • Thank you