Cancer Treatment Overview

Main Types of Cancer Treatment

• Surgical
• Radiation Therapy
• Chemotherapy
• Biologic Therapy

Goal of Cancer Treatment

• Eradicate cancer.
• Treatments can cause harm and toxicity without benefit.

Chemotherapy Agents

Mechanism of Action

• Target different parts of the cell cycle.
• Combination therapy preferred to minimize side effects.

Understanding the Cell Cycle

• G1 Phase: Organelle duplication.
• S Phase: DNA replication.
• G2 Phase: Preparation for mitosis.
• M Phase: Mitosis (cell division).
• Checkpoints: G1, G2, M phase ensure no abnormalities.

DNA Structure and Replication

• Double helix composed of four nucleotides (pyrimidine: thymine, cytosine; purine: adenine, guanine).
• Replication Process:
  • DNA unwound by helicase.
  • Tension resolved by topoisomerase.
  • DNA polymerase creates new strands: leading and lagging strands.

Classes of Chemotherapy Agents

Alkylating Agents

• Bind covalently to DNA (guanine nucleotide).
• Cause cell cycle arrest in G1 or S phase.
• Examples: Nitrogen mustards (cyclophosphamide), Cisplatin. -cisplatin: nephrotoxic:causes hematuria
• cyclophosphamide:hemorrhagic cystitis

Antimetabolites

• Interfere with nucleic acid metabolism, mainly in the S phase.
• Disrupt thymine synthesis and DNA synthesis.
  • Inhibit enzymes like thymidylate synthase and dihydrofolate reductase.
• Examples: Methotrexate, 5-fluorouracil.
• Methotrexate:bleeding antidote: leucovorin -5 - fluorouracil: cerebellar malfunction - ataxia

Anti-tumor Antibiotics

• Examples: Anthracyclines (doxorubicin, daunorubicin).
• Mechanisms:
  • Inhibit topoisomerase II.
  • Inhibit helicase.
  • Induce reactive oxygen species. -Cardiotoxic - monitor ecg

Topoisomerase Inhibitors

• Topoisomerase I Inhibitors: Prevent relaxation of DNA (e.g., Camptothecin).
• Topoisomerase II Inhibitors: Prevent DNA strand rejoining (e.g., Etoposide).

Anti-microtubule Agents

• Target M phase of cell cycle.
• Vinca Alkaloids: Inhibit microtubule assembly.
• Taxanes: Stabilize microtubules, inhibit breakdown.

Hormonal Agents

• Not covered in this lecture but are important.

Conclusion

• Understanding the mechanism of action for chemotherapy agents is crucial.
• Side effects are significant and covered in a separate video.

Note: This lecture focused on the mechanisms and classes of chemotherapy agents. Further information on hormonal agents and side effects is available in other resources.