Cancer occurs when body cells grow uncontrollably and invade nearby tissues. Chemotherapy refers to medicines used to kill or slow down these cancer cells. Because cancer cells divide rapidly, most anticancer drugs target fast-growing cells. However, this also affects some normal tissues, leading to side effects. Treatment is often a combination of drugs to increase effectiveness and reduce resistance.
General Principles of Cancer Chemotherapy
- Given in cycles to allow normal cells to recover
- Often used along with surgery or radiation
- Combination therapy improves outcomes
- Most drugs act on rapidly dividing cells
Classification of Anticancer Drugs
Anticancer drugs are categorized based on how they work on the cancer cell.
1. Alkylating Agents
These drugs damage DNA, preventing cancer cells from dividing.
- Cyclophosphamide
- Ifosfamide
- Melphalan
- Busulfan
Side Effects
- Bone marrow suppression
- Hair loss
- Nausea
- Bladder toxicity (cyclophosphamide)
2. Antimetabolites
These drugs mimic normal cell molecules and block DNA or RNA synthesis.
- Methotrexate
- 5-Fluorouracil (5-FU)
- Cytarabine
Side Effects
- Mouth ulcers
- Bone marrow suppression
- Liver toxicity
3. Antitumor Antibiotics
These drugs bind to DNA and prevent cell replication.
- Doxorubicin
- Daunorubicin
- Bleomycin
Side Effects
- Doxorubicin: heart toxicity
- Bleomycin: lung toxicity
- Nausea and hair loss
4. Plant Alkaloids
These drugs stop cell division by affecting the cell’s microtubules.
Vinca Alkaloids
- Vincristine
- Vinblastine
Taxanes
- Paclitaxel
- Docetaxel
Side Effects
- Nerve damage (vincristine)
- Bone marrow suppression
5. Hormonal Agents
Used for cancers that depend on hormones to grow.
Common Examples
- Tamoxifen (breast cancer)
- Flutamide (prostate cancer)
- Letrozole
- Goserelin
6. Targeted Therapy
These drugs block specific molecules involved in cancer growth.
- Imatinib (for CML)
- Erlotinib
- Trastuzumab (HER2 breast cancer)
Advantages
- More selective
- Fewer side effects than traditional chemotherapy
7. Immunotherapy
Boosts the body’s immune system to fight cancer.
Examples
- Interferons
- Interleukins
- Checkpoint inhibitors (nivolumab, pembrolizumab)
8. Miscellaneous Agents
- Cisplatin (causes DNA cross-linking)
- L-asparaginase (used in leukemia)
Cisplatin Side Effects
- Kidney damage
- Hearing loss
- Nausea and vomiting
General Side Effects of Chemotherapy
- Bone marrow suppression → infections, anemia, bleeding
- Hair loss
- Nausea and vomiting
- Mouth ulcers
- Fatigue
Many side effects are because chemotherapy drugs affect fast-growing normal cells.
Supportive Care in Cancer Chemotherapy
- Antiemetics for vomiting (ondansetron)
- Growth factors to improve blood counts
- Hydration for kidney protection
- Monitoring organs like heart and kidneys
Detailed Notes:
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