Pharmacology 2060A/B Lecture Notes - Lecture 17: Canadian Cancer Society, Prostate Cancer, Radiation Therapy
15 May 2018
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Module 17 – Cancer Chemotherapy
17.1 – Cancer
- Cancer: refers to the uncontrolled proliferation of cells
- Cancer cells are often referred to as neoplastic, meaning they have abnormal and uncontrollable
cell growth
Characteristics of cancer cells making them difficult to treat
- 1. Persistent uncontrollable cell proliferation
- 2. Invasive
o Cancer cells invade adjacent tissue, facilitating cancer growth in different areas of the
body
- 3. Metastatic
o The ability of localized cancer cells to travel to different sites in the body and invade to
form new tumours
o Metastatic cancer is more advanced cancer
- 4. Immortal
o Cancer cells do not die, they continually divide
- 5. Angiogenesis
o Cancer cells develop their own blood vessels to supply nutrients to the cancer cells
o This is a critical step for them to proliferate
Cancer cases by type
- MALES: most prevalent cancer is prostate cancer (30%), lung cancer and colon cancer
- FEMALES: most prevalent cancer is breast cancer (27%), lung cancer, colon cancer
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Cancer case by age
- New cases of cancer:
o Children (0-14) make up a small fraction of cancer cases (0.6%)
o Over 37 years old make up majority of new cancer cases (97%)
o As you get older, prevalence increases
o 30%: 50-64
o 39%: 65-79
o 16%: 80+
Treatment modalities for cancer
1) Surgery – cancer/tumor is removed
- Significantly decrease tumor burden
- Surgery never removes 100% of the cancerous cells
- Must be combined with radiation + chemotherapy
2) Radiation:
- High energy radiation is used to shrink tumours and kill cancer cells
- Radiation therapy damages DNA of both cancerous and noncancerous cells
- Target area where we know cancer is specifically
3) Chemotherapy
- Drugs are used to treat cancer
- As cancerous cells are dividing rapidly, chemotherapeutic drugs target rapidly dividing cells
Cell cycle
- Treatment of cancer involves targeting cell proliferation
- Majority of anticancer drugs target specific parts of the cell cycle
- Go: resting cells not undergoing rapid replication
o The most difficult cells to treat because most of the drugs target cell proliferation
o Can go from Go and reenter cell cycle
- G1: where the cell prepares to synthesize DNA
- S: synthesis phase – cell synthesizes DNA
- G2: cell prepares for mitosis and cell divides
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find more resources at oneclass.com
17.2 – Obstacles to successful chemotherapy
1. Toxicity to normal cells
2. Achieving 100% cell kill
3. Difficult early detection
4. Solid tumors
5. Drug resistance
Toxicity to normal cells
- Neoplastic cells (i.e. cancer cells) are very similar to normal cells
- Therefore it is difficult to specifically target only cancer cells during chemotherapy and normal
cells in the body are affected too (patients get very sick)
- The most cellular toxicity occurs to cells with a high growth fraction
- The growth fraction is the ratio of proliferating cells to cells in the resting (G0) state
- Examples of cells with a high growth fraction include: bone marrow, GI epithelium, hair follicles
and the germinal epithelium of the testes, that gives rise to sperm
- Aside from killing cancer cells, chemotherapeutic drugs kill normal cells
- Normal cells most susceptible to death are cells with high growth fraction
o = bone marrow toxicity, GI disease, losing hair, etc.
Cure of cancer requires 100% cell kill
- In order to cure cancer, we must kill virtually all cancerous cells in the body
- This is difficult as there are not good tests to determine whether cancerous cells are present in
the body in low numbers
- The kinetics of cell death with chemotherapy are first-order
- This means that a constant percentage of cancerous cells are killed at a given dose of drug →
not a constant amount of cells, but a constant percentage of cells are killed over time
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Cancer: refers to the uncontrolled proliferation of cells. Cancer cells are often referred to as neoplastic, meaning they have abnormal and uncontrollable cell growth. Males: most prevalent cancer is prostate cancer (30%), lung cancer and colon cancer. Females: most prevalent cancer is breast cancer (27%), lung cancer, colon cancer. Treatment modalities for cancer: surgery cancer/tumor is removed. Surgery never removes 100% of the cancerous cells. Must be combined with radiation + chemotherapy: radiation: High energy radiation is used to shrink tumours and kill cancer cells. Radiation therapy damages dna of both cancerous and noncancerous cells. Target area where we know cancer is specifically: chemotherapy. As cancerous cells are dividing rapidly, chemotherapeutic drugs target rapidly dividing cells. Majority of anticancer drugs target specific parts of the cell cycle. Go: resting cells not undergoing rapid replication: the most difficult cells to treat because most of the drugs target cell proliferation, can go from go and reenter cell cycle.
