Oncology

1,544 views
1,416 views

Published on

0 Comments
2 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
1,544
On SlideShare
0
From Embeds
0
Number of Embeds
4
Actions
Shares
0
Downloads
116
Comments
0
Likes
2
Embeds 0
No embeds

No notes for slide

Oncology

  1. 1. Oncology; PP 908Oncology; PP 908
  2. 2. What is Cancer?  Cancer is a disorder of cell division (leading cause of death).  Cancer = tumor = neoplasm.  Various forms of cancers differ in: Type. Aggressiveness. Responsiveness to drugs.  Most common cancers are: - Lung, colon, rectal. - Breast (female) & prostate (male).
  3. 3. Cancers Nomenclature:  Carcinomas: epithelial tissues e.g. skin, lung & stomach.  Sarcomas: connective tissues e.g. muscles, cartilage & bones.  Leukemias: blood cells.  Lymphomas: lymphatic system.  Adenomas: glandular tissues.
  4. 4. Characteristics of Cancer Cells: 1. Persistent proliferation & immortality.  Self-sufficiency of growth signals.  Insensitivity to anti-growth signals.  Evading apoptosis.  Expression of telomerase. 2. Dedifferentiation. 3. Invasive growth. 4. Formation of metastases. 5. Sustained angiogenesis.
  5. 5. Etiology of Cancer:  Proto-oncogenes: genes that normally control cell division e.g. bcl-2.  Oncogenes: cancer causing genes.  Tumor suppressor genes: genes that prevent replication of cells that have become cancerous e.g. p53.
  6. 6. Malignant transformations occurs when:  Activation of oncogenes.  Suppression of tumor suppressor genes.  3-7 mutations must occur in a single cell to become cancerous.  Normal functioning immune system usually recognizes these cells & destroy them.
  7. 7. Transformation of Proto-oncogenes to Oncogenes is caused by: - Chemical carcinogens (cigarette smoking pollution). - Pathogens (hepatitis C virus, H. pylori). - Radiation (X-rays). - Hereditary factors. - Drugs (estrogen).
  8. 8. Stages of Malignant Transformation  Initiation: irreversible DNA damage.  Promotion: cells with genetic defects start multiplication. (Promoters are substances that enhance tumor growth by stimulating proliferation, immune suppression, etc.).  Progression: neoplastic cells → malignant tumor → invasion of healthy tissue.
  9. 9.  Tumor can be benign or malignant.  Distinguished by: – Invading neighboring tissues. – Metastasis.
  10. 10. Metastasis of malignant tumors
  11. 11. Treatment Modalities: 11..Surgery (solid tumors(. 2.Radiation (solid tumors(. 3.Drug therapy: – Disseminated cancers (leukemias, lymphomas & widespread metastases. – Some localized tumors e.g. testicular carcinoma. – Adjuvant to surgery & radiation.
  12. 12. Cancer Staging (TNM System):  Stage 0: precancerous.  Stage 1: small localized cancer.  Stage 2: larger cancer; probable lymph nodes involvement.  Stage 3: larger cancer; evident lymph nodes involvement.  Stage 4: metastasis.
  13. 13. Cancer Grading Describes aggressiveness of cancer cells. GX: grade cannot be assessed. G1: well-differentiated. G2: moderately differentiated. G3: poorly differentiated. G4: undifferentiated.
  14. 14. Responsiveness of Some Cancers to Antineoplastic Therapy  High: e.g. Hodgkin’s disease, leukemia & testicular tumors.  Moderate: e.g. breast, bladder & prostate cancer.  Minimal: e.g.e.g. pancreatic, renal, hepatocellular & colorectal cancer.
  15. 15. The Cell Cycle G1 = 40% S = 39% G2 = 19% M = 2% Checkpoints: P27: G1-S phases. P53: G2-M phases.
  16. 16. Growth Fraction  GF = Proliferating cells (S or M phase) /resting cells (G0).  Tissues with high % of proliferating cells have a high growth fraction.  Tissues composed mostly of G0 cells have a low growth fraction.
  17. 17.  Anti-cancer drugs are more toxic to tissues that have a high growth fraction (even normal ones).  Why? because they act by disrupting DNA synthesis or cell division (mitosis).  Accordingly, cells in G0 are resistant to most anti-cancer therapy.
  18. 18.  Solid tumors have a low growth fraction → respond poorly.  Disseminated cancers have a high growth fraction → respond well.  Debulking of tumors: ↓ tumor size by surgery or radiation →↑ responsiveness to therapy.  Recruitment: encouraging resting cells to enter into the cell cycle (how?).
  19. 19. Cell-Cycle Drug Effects 1. Cell-cycle phase-specific drugs:  Must be present for an extended time → given by infusions or in frequent small doses. For example:  5-FU acts in S-phase; t½ 15 min.  Administration by prolonged continuous infusion → ↑ cell kill & improve clinical response.
  20. 20. Cell-cycle phase non-specific drugs (cycle-specific):  Act during any phase including G0.  More toxic to proliferating cells than G0 cells (why?) – Cells in G0 often have time to repair drug-induced damage; whereas proliferating cells don’t.
  21. 21. Making the Decision to Treat Goals of therapy: - Cure. - Improving survival. - Palliation. Outcome of therapy depends on: - General health of patient - Responsiveness of cancer type (size, location, grade, etc.). - Drug resistance.

×