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Cancer = Neoplasia

Cancer = Neoplasia. Abnormal new growth due to excessive increase in number of cells (continuous proliferation). This increase is progressive (non reversible), non physiologic , purposeless. Basic Facts: Neoplasia arises only in cells able to proliferate.

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Cancer = Neoplasia

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  1. Cancer = Neoplasia Abnormal new growth due to excessive increase in number of cells (continuous proliferation). This increase is progressive (non reversible), non physiologic , purposeless.

  2. Basic Facts: Neoplasia arises only in cells able to proliferate. Neoplasia cells do not differentiate. Hyperplasia often pretend neoplasia. Some solid cell tumors may proliferate more slowly than normal cells. Cancer usually follows extracellular stimulus (chemical, physical or biological).

  3. Basic Facts: Cancer cells may be dormant for Long time. Rarely cancer cells may regress spontaneously, but their behavior may be modified with hormones, immunity or chemotherapy. Cancer are usually multicentric

  4. Cancer • Activated oncogenes transform normal cells into cancerous cells. • Transformed cells have increased growth, loss of contact inhibition, tumor specific transplant and T antigens. • The genetic material of oncogenic viruses becomes integrated into the host cell's DNA.

  5. Oncogenic Viruses • Oncogenic DNA Viruses • Adenoviridae • Herpesviridae • Poxviridae • Papovaviridae • Hepadnaviridae • Oncogenic RNA viruses • Retroviridae • Viral RNA is transcribed to DNA which can integrate into host DNA • HTLV 1 • HTLV 2

  6. Tumors are two types Benign or simple tumor. Malignant tumor or cancer

  7. Evidence for immune reactivity to tumors • Tumors that have severe lympho-reticular infiltration have a better prognosis than those that do not.  • Certain tumors regress spontaneously (e.g., melanomas, neuroblastomas).  • There is an increased incidence of primary and secondary malignancies (particularly lympho-reticular tumors) in immunodeficient patients. 

  8. Evidence for immune reactivity to tumors • Antibodies and immune T lymphocytes (in cytotoxicity and mitogenic response assays) have been detected in patients with tumors.  • The young and the very old have an increased occurrence of tumors. These members of the population often have an immune system that is less effective. • Finally, animals can be specifically immunized against various types of tumors.

  9. Tumor associated antigens • Neo-antigens • Onco-fetal antigens • Tumor associated transplantation antigens (TATA) = Tumor rejection.

  10. Onco-fetal antigens • Onco-fetal antigens may appear due to de-repression of  genes that were only expressed early in life. • Alpha-fetoprotein (AFP) • Carcino-embryonic antigen (CEA ).

  11. Alpha-fetoprotein (AFP) • The normal range of AFP concentrations in humans is 0-20 ng/ml. • A 5-fold or higher risein: • A) Hepatomas • B) Non-seminal testicular carcinoma.

  12. Carcino-embryonic antigen (CEA ). • CEA levels in normal people range up to 2.5 ng/ml. • Increase significantly in: • Colorectal cancers

  13. Tumor associated transplantation antigens (TATA) on viral tumors= Oncogenic viruses • Hepatitis-B virus in hepatic carcinoma • Papilloma virus in cervical cancer

  14. Monoclonal anti-tumor antibodies have been used in different forms for the treatment of cancer, either because of their direct effect or as vehicles to target anti-cancer drugs, toxins and the non-specific components of the host's immune system to the site of tumor

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