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PHYSICAL CARCINOGENS 1.RADIATION 2.NONRADIATION AGENTS

PHYSICAL CARCINOGENS 1.RADIATION 2.NONRADIATION AGENTS. RADIATION CARCINOGENESIS 1.ULTRAVIOLET LIGHT 2.IONISING RADIATION. 1.ULTRAVIOLET LIGHT MAIN SOURCE OF UV LIGHT IS SUNLIGHT OTHERS ARE UV LAMPS AND WELDER’S ARCS UV LIGHT PENETRATES ONLY FEW MILLIMETRES OF THE SKIN.

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PHYSICAL CARCINOGENS 1.RADIATION 2.NONRADIATION AGENTS

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  1. PHYSICAL CARCINOGENS1.RADIATION 2.NONRADIATION AGENTS

  2. RADIATION CARCINOGENESIS1.ULTRAVIOLET LIGHT2.IONISING RADIATION

  3. 1.ULTRAVIOLET LIGHTMAIN SOURCE OF UV LIGHT IS SUNLIGHTOTHERS ARE UV LAMPS AND WELDER’S ARCSUV LIGHT PENETRATES ONLY FEW MILLIMETRES OF THE SKIN

  4. MELANIN PIGMENT PROTECTS CAUSE VARIOUS FORMS OF SKIN CANCERS 1.SQUAMOUS CELL CARCINOMA2.BASAL CELL CARCINOMA3.MALIGNANT MELANOMA

  5. WHITE RACEASTRALIANEW ZEALAND AND THOSE LIVING CLOSE TO THE EQUATOR WHO RECEIVE MORE SUNLIGHTFARMERS AND OUTDOOR WORKERS DUE TO THE EFFECT OF ACTINIC LIGHT RADIATION

  6. MECHANISM OF ACTION OF UV LIGHTDNA DAMAGE –MUTATIONNORMALLY DAMAGED DNA GETS REPAIRED

  7. CERTAIN RECESSIVE HEREDITARY DISEASES CHARACTERISED BY A DEFECT IN DNA REPAIR MECHANISM AND ASSOCIATED WITH INCREASE RISK OF CANCER

  8. 1. XERODERMA PIGMENTOSUMSKIN CANCERS AT EARLY AGE2.ATAXIA TELANGIECTASIA –LEUKAEMIA3. BLOOMS SYNDROME-PREDISPOSED TO ALL TYPES CANCERS

  9. 4.FANCONI’S ANAEMIA WITH INCREASED RISK TO DEVELOP CANCERMUTATION OF PROTO-ONCOGENE RAS GENE AND ANTI-ONCOGENETP53

  10. 2.IONISING RADIATION LIKEa. X – RAYSb. β – RAYSc.GAMA RAYSd.RADIOACTIVE ISOTOPESe.PROTONSf.NEUTRONSTHE RISK INCREASES WITH HIGHER DOSAGE

  11. X RAY WORKERS,RADIOTHERAPIST-SKIN CANCERSWATCH WORKERS ENGAGED IN PAINTING THE DIALS WITH LUMINOUS RADIUM- OSTEOSARCOMAMINERS WORKING WITH RADIOACTIVE ELEMENTS

  12. JAPANESE ATOM BOMB SURVIVERS OF THE TWIN CITIES OF HIROSHIMA AND NAGASAKI AFTER WORLD WAR 2

  13. CHERNOBYL NUCLEAR POWER LEAKAGE-USSR-(1985)DAMAGE TO DNA DIRECTLYOR BY FORMATION OF HIGHLY REACTIVE FREE RADICALS WHICH BRING ABOUT DNA DAMAGE

  14. NONRADIATION PHYSICAL CARCINOGENSMECHANICAL INJURY LIKESTONES IN THE GALL BLADDER,URINARY TRACT

  15. HEALED SCARS,ASBESTOSISIMLANTS OF INERT MATERIALS SUCH AS PLASTIC,GLASS IN PROSTHESIS

  16. VIRAL CARCINOGENESISASSOCIATION WAS FIRST OBSERVED BY ITALIAN PHYSICIAN SANARELLI IN 1889

  17. ONCOGENIC VIRUSES ARE TRANSMITTED BY ONE OF 3 ROUTES1.VERTICAL TRANSMISSION-GENETICALLY TRANSMITTED

  18. 2. HORIZONTAL TRANSMISSION DIRECT CONTACT LIKE CONTAGIOUS DISEASES

  19. 3.BY INOCULATION1.DNA ONCOGENIC VIRUSES2.RNA ONCOGENIC VIRUSES

  20. DNA ONCOGENIC VIRUSES5 GROUPS1.PAPOVA VIRUSES2.HERPES VIRUSES3.ADENO VIRUSES4.POX VIRUSES5 HEPADNA VIRUSES

  21. 1.PAPOVAVIRUSESA.PAPILLOMA VIRUSESABOUT 70 TYPES HAVE BEEN IDENTIFIED

  22. HIGH RISK HPV-16,18-CAUSEINVASIVE SQUAMOUS CELL CARCINOMA OF CERVIX,ANUS,PERIANAL REGION,VULVA,PENIS AND ORAL CAVITY

  23. LOW RISK HPV-1,2,4 AND 7CAUSE SQUAMOUS CELL PAPILLOMAS,HPV 6 AND 11CAUSE GENITAL WARTS

  24. B. SV 40 VIRUS A PAPOVA VIRUS?MESOTHELIOMA OF PLEURA IN HUMAN BEINGS

  25. 2 . HERPES VIRUSESA. EPSTEIN-BARR VIRUS(EBV) a.BURKTT’S LYMPHOMA( A B CELL LYMPHOMA)FIRST NOTICED IN AFRICAN CHILDREN BY BURKITT IN 1958.

  26. 90% BURKITT ‘S LYMPHOMA TUMOUR CELLS HAVE EBV DNA HIGH ANTIBODY TITERS.OCCURS IN IMMUNOSUPRESSION CASES AS IN MALARIA AND HIV.

  27. b.ANAPLASTIC NASOPHARYNGEALCARCINOMA-SOUTH EAST ASIA CHINA, ESKIMOS

  28. 100% CASES CARRY EBV DNA IN TUMOUR CELLS.HIGH TITERS OF ANTIBODY TO EBV ANTIGENS

  29. B . HUMAN HERPES VIRUS 8 (HHS 8)OR KAPOSI’S SARCOMA ASSOCIATED HERPES VIRUS(KSHS)A VASCULAR NEOPLASM COMMON IN AIDS PATIENTS

  30. HHS8 VIRUS ALSO CAUSE B CELL LYMPHOMA3. ADENOVIRUSES NOT IN HUMAN BEINGS4.POXVIRUS-SQUAMOUS CELL PAPILLOMA

  31. 5.HEPADNAVIRUSHBV BELONGS TO THIS FAMILYCAUSE HEPATOCELLULARCARCINOMA CONTINUED HEPATOCYTE DESTRUCTION

  32. FOLLOWED BY PROLIFERATION WHICH MAKES THEM VULNERABLE TO THE ACTION OF AFLATOXIN FROM ASPERGILLOUS FLAVUS MUTATION-HCCHCV – 50% CASES OF HCC

  33. RNA ONCOGENIC VIRUSRETROVIRUSES HAVING ENZYME REVERSE TRANSCRIPTASE(RT)3 SUB-GROUPS 1.ACUTE TRANSFORMING VIRUSES2 . SLOW TRANSFORMING VIRUSES

  34. 3.HUMAN T CELL LYMPHOTROPIC VIRUSES(HTLV).RNA VIRUSES HAVE 3 GENESgag,pol,env genes

  35. ACUTE TRANSFORMING VIRUSESTRANSFORM ALL THE INFECTED CELLS INTO MALIGNANT CELLS RAPIDLY.

  36. THEY ARE DEFECTIVE VIRUSES WHERE v-onc HAS SUBSTITUTED gag,pol AND env AND THESE DEFECTIVE VIRUSES CANNOT REPLICATE BY THEMSELVES

  37. UNLESS THE HOST CELL IS INFECTED BY ANOTHER HELPER VIRUS.NOT FOUND TO BE ONCOGENIC TO HUMANS.

  38. 2.SLOW TRANSFORMING VIRUSESMOUSE MAMMARY TUMOUR VIRUS(BITTNER MILKFACTOR)INSERTIONAL MUTAGENESIS-NEOPLASTIC TRANSFORMATIONNOT ONCOGENIC TO HUMANS

  39. 3.HUMAN T CELL LYMPHOTROPIC VIRUSES(HTLV)ONLY RETROVIRUS IMPLICATED IN HUMAN CANCER1.HTLV 1- ADULT T CELL LEUKKAEMIA LYMPHOMA SYNDROME2.HTLV II –T CELL VARIANT OF HAIRY CELL LEUKAEMIA

  40. 3. HTLV III(HTLV-III is an outdated term for HIV-14. HTLV IVIMMUNOSUPPRESSION PLAYS A SUPPORTIVE ROLE IN NEOPLASTIC TRANSFORMATIONNO v-onc gene MEDIATIONNO INSERTIONAL MUTAGENESIS

  41. HTLV I - HAS tat gene IN ADDITION TO gag,pol,env genestat gene STIMULATES NEOPLASTIC CELL PROLIFERATION OF T CELLS.

  42. FIRST POLYCLONALTHEN MONOCLONALPROLIFERATION -LEUKAEMIALYMPHOMA

  43. HTLV II - TRANSFORMATION BY PROMOTER INSERTION-ONCOGENESIS BY ONCOGENES AND GROWTH FACTORS

  44. MODE OFDNA VIRAL ONCOGENESISa . INFECTION –REPLICATION-CYTOLYSIS-RELEASE OF VIRUSESb . INTEGRATION –VIRAL DNAINTEGRATES INTO HOST DNA-NEOPLASTIC TRANSFORMATION

  45. MODE OF RNA VIRALONCOGENESISRETROVIRUS CONTAIN 2 IDENTICAL RNA STRANDSAND ENZYME REVERSE TRANSCRIPTASE

  46. RT ACTS AS A RNA DEPENDENT DNA SYNTHETASEACT AS TEMPLATE TO SYNTHESISE ASINGLE STRAND OF MATCHING VIRAL DNA.

  47. SINGLE STRAND OF VIRAL DNA IS THEN COPIED BY DNA DEPENDENT DNA POLYMERASE TO FORM ANOTHER STRAND OF COMPLIMENTARY DNA

  48. THIS RESULTS IN DOUBLE STRANDED VIRAL DNA FORMATION OR PROVIRUS FORMATION

  49. PROVIRAL DNA GETS INTEGRATED INTO HOST CELL GENOME - NEOPLASM

  50. SUMMARY OF VIRUSES AND HUMAN CANCERI.BENIGN TUMOURSa.HUMAN PAPILLOMA VIRUS -HUMAN WARTSb.POXVIRUS - MOLLUSCUM CONTAGIOSUM

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