AIM STEP 10
Student Memory Support
Topic 19 — Anticancer Pharmacology and Principles of Cancer Chemotherapy
3rd Year MBBS • Multisystem • High-yield memory reinforcement and last-minute revision
1. High-Yield Flashcards
Tap each question to reveal the answer.
What is meant by a cell cycle-specific anticancer drug?
A drug that acts most effectively during a particular phase of the cell cycle.
How does P-glycoprotein produce resistance to anticancer drugs?
It pumps cytotoxic drugs out of tumor cells, lowering their intracellular concentration.
What is the main mechanism of alkylating agents?
They form covalent bonds with DNA and produce cross-linking that interferes with replication.
Which characteristic toxicity is associated with busulfan?
Pulmonary fibrosis.
Which metabolite causes cyclophosphamide-induced hemorrhagic cystitis?
Acrolein.
Which agent protects against cyclophosphamide-induced bladder toxicity?
Mesna.
Which two toxicities are strongly associated with cisplatin?
Nephrotoxicity and ototoxicity.
Which enzyme is inhibited by methotrexate?
Dihydrofolate reductase.
Which rescue agent is used after high-dose methotrexate?
Folinic acid, also called leucovorin.
Why does allopurinol increase 6-mercaptopurine toxicity?
It inhibits xanthine oxidase and reduces 6-mercaptopurine breakdown.
Which enzyme is inhibited by 5-fluorouracil?
Thymidylate synthase.
How do vincristine and vinblastine block mitosis?
They bind tubulin and inhibit microtubule polymerization, causing metaphase arrest.
What is the major toxicity difference between vincristine and vinblastine?
Vincristine causes prominent neurotoxicity; vinblastine causes prominent bone marrow suppression.
Which serious toxicity is associated with doxorubicin?
Cardiomyopathy.
Which characteristic toxicity is associated with bleomycin?
Pulmonary toxicity that may progress to pulmonary fibrosis.
Which hormonal anticancer drugs are associated with breast and prostate cancer?
Tamoxifen for ER-positive breast cancer; flutamide and goserelin for androgen-dependent prostate cancer.
2. Mnemonics
Mnemonic Title: Cytotoxic Rescue Drugs
MeLeDex
Meaning: Mesna → cyclophosphamide; Leucovorin → methotrexate; Dexrazoxane → doxorubicin.
Mnemonic Title: Vinca Toxicity Difference
CRISTI = nerves, BLAST = marrow
Meaning: Vincristine → neurotoxicity; Vinblastine → bone marrow suppression.
Mnemonic Title: Classic Organ Toxicities
Heart–Lung–Kidney
Meaning: Doxorubicin → heart; bleomycin → lung; cisplatin → kidney.
3. Memory Tables
Vincristine vs Vinblastine
| Feature | Vincristine | Vinblastine |
|---|---|---|
| Target | Tubulin | Tubulin |
| Cell phase | M phase | M phase |
| Main toxicity | Neurotoxicity | Myelosuppression |
Chemotherapy Timing
| Modality | When Given | Main Purpose |
|---|---|---|
| Induction | Initial treatment | Achieve remission |
| Neoadjuvant | Before local therapy | Reduce tumor size |
| Adjuvant | After local therapy | Destroy microscopic residual cells |
| Maintenance | After remission | Reduce relapse |
4. Rapid Revision Points — Last-Minute Revision
Must Remember:
- P-glycoprotein increases drug efflux and produces multidrug resistance.
- Cyclophosphamide produces acrolein; mesna protects the bladder.
- Cisplatin forms DNA cross-links and may damage kidneys and hearing.
- Methotrexate inhibits dihydrofolate reductase; leucovorin is the rescue agent.
- Allopurinol increases toxicity of 6-mercaptopurine and azathioprine.
- 5-Fluorouracil inhibits thymidylate synthase.
- Vinca alkaloids inhibit microtubule polymerization and arrest mitosis.
- Doxorubicin is associated with cardiomyopathy; dexrazoxane reduces important cardiac toxicity.
- Bleomycin causes pulmonary toxicity with relatively little bone marrow suppression.
- Tamoxifen is used in ER-positive breast carcinoma; flutamide and goserelin are used in prostate carcinoma.
Common KMU Trap: Vincristine and vinblastine share the same microtubule mechanism, but their dominant toxicities differ: vincristine affects nerves; vinblastine suppresses marrow.
5. Clinical Memory Hooks
Hematuria during cyclophosphamide therapy → acrolein-induced hemorrhagic cystitis → mesna.
Tinnitus plus rising creatinine during chemotherapy → cisplatin toxicity.
Paresthesia plus severe constipation with preserved marrow counts → vincristine neurotoxicity.
Dry cough and interstitial lung changes during lymphoma treatment → consider bleomycin-related pulmonary injury.
6. Starred High-Yield Exam Points
- ⭐ Methotrexate → dihydrofolate reductase inhibition → leucovorin rescue.
- ⭐ Cyclophosphamide → acrolein → hemorrhagic cystitis → mesna.
- ⭐ Doxorubicin → cardiomyopathy → dexrazoxane.
- ⭐ Vincristine → neurotoxicity; vinblastine → bone marrow suppression.
- ⭐ Bleomycin → pulmonary fibrosis with relatively little marrow suppression.
- ⭐ Allopurinol reduces 6-mercaptopurine breakdown and increases toxicity.
- ⭐ Goserelin initially raises androgen levels before GnRH receptor down-regulation suppresses testosterone.