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  • MEDICAL AND BIOLOGICAL IMPORTANCE1. Cancer is a major health problem affecting humans throughout the world. Several typesof cancers affecting major organs like lung, brain, kidney, colon, breast, oesophagus andstomach have been identified.2. Rate of incidence of cancer of particular organ in particular population depends onseveral factors like age, sex, dietary habits, environment, geographical location, geneticmake up, culture, physical exercise etc. For example in India oral cancer is common inbetal nut chewing regions and in reverse smokers. Stomach cancer is more in Japaneseand Chinese people. Colon cancer is common in advanced countries and lung cancer iscommon in smokers. Old people are more prone to any type of cancer. Brain cancer andblood cancer are common in children. Men above 50 are prone to prostate cancer.Women above 45 are prone to breast, ovarian and cervical cancers.3. Rate of incidence of cancer of particular organ varies from developed countries todeveloping countries. (Table 21.1). Lung and colorectal cancers are high in developedcountries while stomach and cervical cancer are more in developing countries. Furtherin India pharyngeal cancers are high in Western India where as stomach cancers aremore common in Southern India.Nearly 10 million new cases of cancer are diagnosed globally every year. It is estimatedthat by 2020 ten million persons would die of cancer every year World wide.Table 21.1 Cancer incidence rate in developed and developing CountriesCancer site Developed countries Developing countriesLung 62 24Colon and rectum 20-45 2-8Stomach 10 60Cervix 14 30Prostate 30 10Mouth and pharynx 13 25
  • Generally cancers are named according to the organ affected. However they are classifiedbased on the three embryonic germ layers from which tissue or organ is derived.
  • Cancer ppt BIOCHEMISTRY

    1. 1. Dr Vijay Marakala,M.D Biochemistry, SIMS&RC.
    2. 2. Cancer is malignant growth (un controlled growth) and proliferation of cells.
    3. 3. •Uncontrolled growth of a single altered cell. = Mutations = Cancer •Cancer cells grow faster, adapt better. •They live at the cost of our living.
    4. 4. Normal cells Mutated cells Proliferation of mutated cells Uncontrolled growth Invasion Metastasis
    5. 5. Multilayer Growth Grow over one another Motility Rounder Shape Due to loss of contact inhibition
    6. 6. Altered synthesis of certain growth factors Lactic acidosis ↓Catabolism of pyrimidines ↑Synthesis of DNA and RNA Altered gene regulation Stimulates anabolic processes
    7. 7. Carcinomas Cancer of cells or organs derived from either ectoderm or endoderm Cancers of epithelial tissues, nervous tissues, glands etc Sarcomas Cancers of tissues of mesodermal origin Cancers of bone, cartilage, connective tissue, muscle etc B/O the 3 embryonic germ layers from which tissue or organ is derived
    8. 8. Carcinomas Adenocarcinoma Squamous cell carcinoma Gliomas Sarcomas Osteosarcoma Fibrosarcoma
    9. 9. Estrogen OCP Anabolic steroids Hormonal Hepatitis B virus Retro viruses Biological Cigarette smoke Aflatoxins Chemical X-rays γ-rays UV rays Physical
    10. 10. Radiation Direct effect • Single or double strand breaks • Elimination of purine/pyrimidine bases • Cross-linking of strands • Formation of pyrimidine dimers Indirect effects • Production of free radicals
    11. 11. • Carcinogens are generally electrophiles • Electrophiles readily attack nucleophilic group of DNA • Carcinogens may bind covalently to cellular DNA Direct acting Procarcinogens Target DNA
    12. 12. Procarcinogens Procarcinogens Proximate carcinogens Ultimate carcinogens
    13. 13. ONCOGENIC VIRUSES Virus infect host cell DNA virus binds tightly to host cell DNA Altered gene expression Altered protein [oncoprotein]
    14. 14. • Endometrial carcinoma Estrogen • Breast cancer OCP • Liver carcinoma Anabolic steroids
    15. 15. • Normal genes which inhibit cell division Tumor suppressor gene • Normal genes which stimulate cell division Proto-oncogene • Genes capable of causing cancer Oncogenes
    16. 16. Inhibitors - Stimulators + Tumour supressor gene Proto- oncogene Inhibitors - Stimulators + +
    17. 17. ACTIVATION OF PROTO-ONCOGENE TO ONCOGENE Viral insertion into chromosome Chromosomal translocation Gene amplification Point mutation