Carcinogenesis Lecture Notes PDF

Carcinogens are agents that can cause cancer Cancer -The disease caused by an uncontrolled division of abnormal cells in a part of the body. -A malignant growth of tumor resulting from such a division of cells. Normal cell, cancer cell and tumour.neoplasm- An abnormal new growth of tissue that gr...

Carcinogens are agents that can cause cancer Cancer -The disease caused by an uncontrolled division of abnormal cells in a part of the body. -A malignant growth of tumor resulting from such a division of cells. Normal cell, cancer cell and tumour.neoplasm- An abnormal new growth of tissue that grows more rapidly than normal cells and will continue to grow if not treated. These growths will compete with normal cells for nutrients. This is a non-specific term that can refer to benign or malignant growths. A synonym for tumor. tumor- The more commonly used term for a neoplasm. The word tumor simply refers to a mass. This is a general term that can refer to benign or malignant growths. benign tumor- A non-malignant/non-cancerous tumor. A benign tumor is usually localized, rarely spreads to other parts of the body and responds well to treatment. However, if left untreated, benign tumors can lead to serious disease. malignant tumor- Cancer. A malignant tumor is resistant to treatment, may spread to other parts of the body and often recurs after removal. cancer- A malignant tumor (a malignant neoplasm).  What causes cancer?.Gentic 1) Oncogenes 2) Tumour suppressor genes..  Biological Agents Human viral pathogens oncogenic retroviruses (HIV) DNA viruses (Epstein-Barr, HSV-2, papilloma, HBV) Bacteria, biotransformation Endoparasites (Schistomsoma spp.) Physical agents Ionizing radiation O2 free radicals DNA damage Nonionizing radiation UV between 280 - 320 nm Chemical Dye workers and cancer of the lung Luminous paint and bone cancer Mining and lung cancer Arsenic Asbestos chrome nickel salts Nitroso compounds certain drugs.. Immunosuppressant/ immunotoxins. An immunosuppressant is any substance that performs immunosuppression of the immune system. They may be either exogenous, as immunosuppressive drugs, or endogenous, as ,e. g., testosterone. When the immune system function is suppressed, there is an increased susceptibility to infectious diseases and cancers. Predisposing Factors Dietary Caloric intake Protein deficiency, high fat Carotenes and retinoids - deficiency Tocopherols - deficiency Selenium (glutathione peroxidase) - deficiency Zinc deficiency Flavanoids (enzyme inhibition) - deficiency  Comparison between the characteristics of normal and cancer cells Normal cells Normal body cells have a number of important characteristics. They can Reproduce themselves exactly Stop reproducing at the right time Stick together in the right place Self destruct if they are damaged Become specialized or 'mature‘ Show specific and normal functioning Cancer cells ✓ Cancer cells are different to normal cells in several ways. ✓ They don't die if they move to another part of the body ✓ Cancer cells don’t stop reproducing ✓ Cancer cells stay immature and don’t specialize ✓ Cancer cells do not stick together ✓ Tendency to invade surrounding tissue ✓ Tendency to travel beyond site of origin ✓ metastasis may occur late Recent Theory of Carcinogenesis Viral theory of carcinogenesis Two-stage mechanism of Ca.genesis two processes: initiation, promotion followed by progression Steps in Chemical Carcinogenesis 1. Biotransformation 2.Initiation: 3.Fixation: 4. Gene expression, transformation 5. Neoplastic growth, proliferation 6.Progression, 7. Metastasis  Prevention-carcinogenesis perspectives Prevention of carcinogenesis and inhibition of cancer, tumor by Better dietary practices Screening-regularly Consider better social practices Avoid contamination Take proper medication