Anticancer Drugs Practice Questions

Q: Which of the following is/are used in the hormonal therapy of breast carcinoma?

All of the above. Hormonal therapy is a cornerstone in the management of hormone receptor-positive (ER/PR+) breast cancer. The goal is to either block estrogen receptors or decrease circulating estrogen levels. **Explanation of Options:** * **Tamoxifen (Option C):** This is a **Selective Estrogen Receptor Modulator (SERM)**. It acts as a competitive antagonist at estrogen receptors in breast tissue, making it the gold standard for pre-menopausal women. It also has agonist effects on the bone (preventing osteoporosis) and endometrium (increasing the risk of endometrial carcinoma). * **Letrozole and Anastrozole (Options A & B):** These are **Third-generation Aromatase Inhibitors (AIs)**. They inhibit the enzyme aromatase, which converts peripheral androgens into estrogens. Since they cannot stop ovarian estrogen production, they are primarily used in **post-menopausal women**. **Why "All of the above" is correct:** All three drugs are FDA-approved and standard-of-care agents used to treat or prevent the recurrence of breast carcinoma by targeting the estrogen signaling pathway. **High-Yield Clinical Pearls for NEET-PG:** 1. **Drug of Choice:** Tamoxifen is preferred in pre-menopausal women; Aromatase Inhibitors (Letrozole/Anastrozole) are preferred in post-menopausal women. 2. **Side Effects:** Tamoxifen increases the risk of **thromboembolism** and **endometrial cancer**. Aromatase inhibitors are associated with an increased risk of **osteoporosis** and joint pain. 3. **Fulvestrant:** A Selective Estrogen Receptor Downregulator (SERD) used in tamoxifen-resistant cases. 4. **Trastuzumab:** Not a hormonal agent, but a monoclonal antibody used for HER2/neu positive breast cancer.

Q: All of the following statements about methotrexate are true EXCEPT:

Folic acid reverses its toxic effects.. ### Explanation **1. Why Option C is the correct (False) statement:** Methotrexate (MTX) is a folate antagonist that works by inhibiting the enzyme **Dihydrofolate Reductase (DHFR)**. This prevents the conversion of dihydrofolate to tetrahydrofolate (THF). Once MTX binds to DHFR, the cell’s pool of active folate is depleted. Administering **Folic acid** is ineffective because it also requires DHFR to be converted into its active form. To reverse MTX toxicity, we must provide **Folinic acid (Leucovorin/Citrovorum factor)**, which is already a reduced form of folate (N5-formyl-THF) that bypasses the inhibited enzyme. This is known as **"Leucovorin Rescue."** **2. Analysis of other options:** * **Option A:** MTX is a classic **Antimetabolite**. These drugs are **Cell Cycle Specific (CCS)** and act specifically during the **S-phase** by inhibiting DNA synthesis. * **Option B:** Like most cytotoxic drugs, MTX targets rapidly dividing cells. Its primary dose-limiting toxicities include **Bone Marrow Suppression** (myelosuppression) and damage to **Epithelial structures** (leading to oral mucositis and GI ulceration). * **Option D:** MTX is highly effective against trophoblastic tumors and remains the **Drug of Choice for Choriocarcinoma**, often achieving a 100% cure rate in low-risk cases. **3. NEET-PG High-Yield Clinical Pearls:** * **Resistance:** Occurs via decreased drug uptake, decreased polyglutamation, or altered DHFR with lower affinity for MTX. * **Excretion:** MTX is primarily excreted renally. **Salicylates and Sulfonamides** can displace MTX from plasma proteins and inhibit its renal secretion, leading to fatal toxicity. * **Other Uses:** Low-dose MTX is a first-line **Disease-Modifying Antirheumatic Drug (DMARD)** for Rheumatoid Arthritis and is used in Ectopic Pregnancy. * **Specific Toxicity:** Long-term use can lead to **Hepatic Fibrosis/Cirrhosis**.

Q: Which of the following drugs cause metaphase arrest?

Vincristine, Paclitaxel, Colchicine. ### Explanation **1. Mechanism of Metaphase Arrest** Metaphase arrest occurs when drugs interfere with the **mitotic spindle apparatus**, preventing the separation of sister chromatids. This triggers the "spindle assembly checkpoint," halting the cell cycle in the **M-phase (Metaphase)**. * **Vinca Alkaloids (Vincristine/Vinblastine):** These bind to tubulin and **inhibit polymerization**, preventing the formation of microtubules ("Spindle poisons"). * **Taxanes (Paclitaxel/Docetaxel):** These bind to tubulin and **enhance polymerization**, stabilizing microtubules and preventing their disassembly ("Spindle stabilizers"). * **Colchicine:** Primarily used in gout, it also inhibits microtubule polymerization, leading to metaphase arrest. **2. Analysis of Incorrect Options** * **Option B & C (Griseofulvin):** While Griseofulvin is an antifungal that interferes with microtubule function, it is **not** classified as a standard anticancer drug. Furthermore, Option C includes Etoposide. * **Option C & D (Etoposide):** Etoposide is a **Topoisomerase II inhibitor**. It acts primarily in the **S and G2 phases** of the cell cycle, not the M-phase. It causes DNA strand breaks rather than spindle interference. **3. NEET-PG High-Yield Pearls** * **Cell Cycle Specificity:** Vincas and Taxanes are **M-phase specific**. * **Dose-Limiting Toxicities:** * **Vincristine:** Peripheral neuropathy (Areflexia, paralytic ileus). Note: It is relatively bone marrow sparing. * **Vinblastine:** Bone marrow suppression ("Blast" the marrow). * **Paclitaxel:** Hypersensitivity reactions (pre-treat with dexamethasone/antihistamines) and neuropathy. * **Other M-phase inhibitors:** Ixabepilone (Epothilones) and Eribulin.

Q: Which of the following agents is not a proliferation-independent agent?

Vincristine. ### Explanation Anticancer drugs are classified based on their relationship to the cell cycle into two categories: **Cell Cycle-Specific (CCS)** and **Cell Cycle-Nonspecific (CCNS)**. **1. Why Vincristine is the Correct Answer:** Vincristine is a **Cell Cycle-Specific (CCS)** agent. It belongs to the Vinca alkaloid class, which acts specifically during the **M-phase (Mitosis)** of the cell cycle. It binds to tubulin and inhibits its polymerization into microtubules, preventing the formation of the mitotic spindle. Because its efficacy is strictly dependent on the cell being in the process of division (proliferation), it is a **proliferation-dependent** agent. **2. Why the other options are incorrect:** * **Cyclophosphamide, Melphalan, and Carmustine:** These are all **Alkylating Agents**. Alkylating agents work by covalently bonding alkyl groups to DNA, leading to cross-linking and DNA strand breaks. This damage occurs regardless of whether the cell is actively dividing or in a resting state ($G_0$ phase). Therefore, they are classified as **Cell Cycle-Nonspecific (CCNS)** or **proliferation-independent** agents. ### NEET-PG High-Yield Pearls: * **M-Phase Specific Drugs:** Vinca alkaloids (Vincristine, Vinblastine) and Taxanes (Paclitaxel, Docetaxel). *Mnemonic: Vinca prevents assembly; Taxanes prevent disassembly.* * **S-Phase Specific Drugs:** Antimetabolites (Methotrexate, 5-FU, Cytarabine). * **$G_2$-Phase Specific Drugs:** Bleomycin. * **Dose-limiting toxicity of Vincristine:** Peripheral neuropathy (unlike Vinblastine, which is Bone Marrow Suppression). * **Carmustine/Lomustine:** Highly lipid-soluble nitrosoureas used primarily for brain tumors because they cross the blood-brain barrier.

Q: Which of the following is an inhibitor of DNA synthesis?

Actinomycin. The correct answer is Actinomycin (Dactinomycin) [2]. **Mechanism of Action:** Actinomycin acts by binding to the guanine residues of DNA, forming a stable complex. This intercalates between the DNA base pairs, which inhibits the movement of RNA polymerase, thereby preventing transcription [2]. At higher concentrations, it also interferes with **DNA replication (DNA synthesis)** by inhibiting DNA-dependent DNA polymerase [1]. **Analysis of Incorrect Options:** * **A. Penicillin:** This is a Beta-lactam antibiotic that inhibits **cell wall synthesis** by binding to Penicillin-Binding Proteins (PBPs) and preventing the cross-linking of peptidoglycan chains. * **B. Polymyxin:** These are cationic detergents that disrupt the **cell membrane** integrity of Gram-negative bacteria, leading to leakage of intracellular contents. * **C. Chloramphenicol:** This is a bacteriostatic antibiotic that inhibits **protein synthesis** by binding to the 50S ribosomal subunit and preventing peptidyl transferase activity. **High-Yield Clinical Pearls for NEET-PG:** * **Actinomycin D** is primarily used as a chemotherapy agent for pediatric tumors like **Wilms’ tumor**, Ewing’s sarcoma, and Rhabdomyosarcoma. * **Other DNA Synthesis Inhibitors:** Fluoroquinolones (inhibit DNA Gyrase/Topoisomerase), Metronidazole (causes DNA strand breakage), and Acyclovir (inhibits viral DNA polymerase) [1]. * **Mnemonic for Protein Synthesis Inhibitors:** **"Buy AT 30, CELL at 50"** (Aminoglycosides/Tetracyclines at 30S; Chloramphenicol/Erythromycin/Linezolid/Lincosamides at 50S).

Q: Which antineoplastic drug is associated with very high cardiac toxicity?

Doxorubicin. **Explanation:** **Doxorubicin** (an Anthracycline antibiotic) is the correct answer because its most notorious dose-limiting toxicity is **cardiotoxicity**. This occurs via two mechanisms: the generation of iron-dependent **free radicals** (superoxide anions) that cause oxidative stress to myocytes, and the inhibition of **Topoisomerase IIβ**, leading to mitochondrial dysfunction and cell death. * **Acute toxicity:** Presents as arrhythmias or ECG changes (transient). * **Chronic toxicity:** Leads to irreversible, dose-dependent **Dilated Cardiomyopathy** and congestive heart failure. The risk increases significantly once the cumulative dose exceeds **550 mg/m²**. **Analysis of Incorrect Options:** * **A. Bleomycin:** Primarily associated with **Pulmonary Fibrosis** (due to lack of bleomycin hydrolase in lungs) and skin hyperpigmentation. It is "heart-friendly" but "lung-toxic." * **B. Actinomycin–D (Dactinomycin):** Mainly causes significant bone marrow suppression and is used primarily in pediatric tumors (Wilms tumor, Ewing sarcoma). * **C. Mitomycin–C:** Known for causing **Hemolytic Uremic Syndrome (HUS)** and delayed bone marrow suppression. **High-Yield Clinical Pearls for NEET-PG:** 1. **Dexrazoxane:** An iron-chelating agent administered to prevent/reduce Doxorubicin-induced cardiotoxicity. 2. **Monitoring:** Periodic **ECHO or MUGA scans** are mandatory to monitor the Left Ventricular Ejection Fraction (LVEF) in patients on Anthracyclines. 3. **Liposomal Doxorubicin:** Formulated to reduce cardiac uptake and decrease toxicity.

Q: Which of the following is a cardiotoxic anticancer drug?

Doxorubicin. **Explanation:** **Doxorubicin** is the correct answer because it belongs to the **Anthracycline** class of antibiotics, which are notorious for their dose-dependent **cardiotoxicity** [1]. The underlying mechanism involves the generation of **superoxide free radicals** and iron-dependent lipid peroxidation, which damages the myocardial cells (which have low levels of protective catalase) [2]. This toxicity manifests in two forms: 1. **Acute:** Transient ECG changes and arrhythmias [1]. 2. **Chronic:** Cumulative dose-related **Dilated Cardiomyopathy (DCM)** and congestive heart failure [1]. **Analysis of Incorrect Options:** * **A. Bleomycin:** Primarily known for **Pulmonary Fibrosis** (interstitial pneumonitis). It lacks significant cardiac side effects but can cause skin hyperpigmentation. * **C. 5-Fluorouracil:** An antimetabolite primarily associated with GI toxicity, hand-foot syndrome, and rarely, coronary vasospasm (angina) [4], but it is not the classic "cardiotoxic" drug compared to Doxorubicin. * **D. Dactinomycin:** An antitumor antibiotic used in pediatric tumors (Wilms tumor) [3]; its dose-limiting toxicity is primarily bone marrow suppression and GI distress. **High-Yield Clinical Pearls for NEET-PG:** * **Antidote:** **Dexrazoxane** (an iron chelator) is used to prevent/reduce Doxorubicin-induced cardiotoxicity [2]. * **Monitoring:** Periodic **ECHO/MUGA scans** to monitor Left Ventricular Ejection Fraction (LVEF) are mandatory [1]. * **Cumulative Dose:** The risk of heart failure increases significantly when the cumulative dose of Doxorubicin exceeds **450–550 mg/m²** [1]. * **Liposomal Doxorubicin:** This formulation is used to reduce cardiotoxicity by altering drug distribution.

Q: Which of the following anticancer drugs exhibits dose-dependent least neurotoxicity?

Bleomycin. **Explanation:** The correct answer is **Bleomycin**. In the context of the options provided, Bleomycin is unique because its dose-limiting toxicity is **pulmonary fibrosis**, not neurotoxicity. It has virtually no significant penetration into the central nervous system and does not typically cause peripheral neuropathy, making it the drug with the least neurotoxicity among the choices. **Why the other options are incorrect:** * **Cisplatin:** This platinum-based agent is notorious for significant **dose-dependent neurotoxicity**, primarily manifesting as peripheral sensory neuropathy (stocking-glove pattern) and ototoxicity (high-frequency hearing loss). * **Vinblastine:** As a microtubule inhibitor (Vinca alkaloid), it interferes with axonal transport. While Vinblastine is more associated with bone marrow suppression than Vincristine, it still carries a significant risk of peripheral neuropathy and autonomic dysfunction. * **Doxorubicin:** While its primary dose-limiting toxicity is **cardiotoxicity**, it can contribute to "chemo-brain" (cognitive impairment) and, in high doses or specific formulations, exhibits more neurological interference than Bleomycin. **High-Yield Clinical Pearls for NEET-PG:** 1. **Bleomycin Specifics:** It acts by inducing free radical formation, causing DNA strand breaks. It is "cell cycle specific" for the **G2 phase**. 2. **The "B" Rule:** Remember **B**leomycin for **B**low (Pulmonary Fibrosis) and **B**one marrow sparing (it is one of the few anticancer drugs that does not cause significant myelosuppression). 3. **Cisplatin Triad of Toxicity:** Nephrotoxicity (prevented by Amifostine/hydration), Ototoxicity, and Peripheral Neuropathy. 4. **Vincristine vs. Vinblastine:** Vincristine is dose-limited by **Neurotoxicity**; Vinblastine is dose-limited by **Bone marrow suppression** ("Blast" = Bone marrow).

Question 1

Which of the following is/are used in the hormonal therapy of breast carcinoma?

Accepted Answer

All of the above

Answer

Letrozole

Answer

Anastrozole

Answer

Tamoxifen

Question 2

Which of the following is the main mechanism by which mechlorethamine exerts its cell killing?

Accepted Answer

Alkylating DNA, causing cross-links between parallel DNA strands

Answer

Blocking microtubular assembly and mitosis during M-phase

Answer

Inhibiting topoisomerase, preventing repair of DNA strand breaks

Answer

Intercalating in DNA strands, thereby preventing DNA replication by mRNA

Question 3

All of the following statements about methotrexate are true EXCEPT:

Accepted Answer

Folic acid reverses its toxic effects.

Answer

It is cell cycle specific and kills cells in the S phase.

Answer

Its toxicity primarily affects bone marrow and epithelial structures.

Answer

It is the drug of choice for choriocarcinoma.

Question 4

Which of the following drugs cause metaphase arrest?

Accepted Answer

Vincristine, Paclitaxel, Colchicine

Answer

Griseofulvin, Vincristine, Paclitaxel

Answer

Griseofulvin, Paclitaxel, Etoposide

Answer

Vincristine, Etoposide, Colchicine

Question 5

Which of the following agents is not a proliferation-independent agent?

Accepted Answer

Vincristine

Answer

Carmustine

Answer

Melphalan

Answer

Cyclophosphamide

Question 6

Which of the following is an inhibitor of DNA synthesis?

Accepted Answer

Actinomycin

Answer

Penicillin

Answer

Polymyxin

Answer

Chloramphenicol

Question 7

Which antineoplastic drug is associated with very high cardiac toxicity?

Accepted Answer

Doxorubicin

Answer

Bleomycin

Answer

Actinomycin–D

Answer

Mitomycin–C

Question 8

A 56-year-old female was prescribed trastuzumab. Which of the following statements regarding this drug is FALSE?

Accepted Answer

It is a chimeric antibody containing human and mouse components.

Answer

It is used for the treatment of HER2-positive breast carcinoma.

Answer

It can cause cardiac toxicity.

Answer

It is not effective orally.

Question 9

Which of the following is a cardiotoxic anticancer drug?

Accepted Answer

Doxorubicin

Answer

Bleomycin

Answer

5-Fluorouracil

Answer

Dactinomycin

Question 10

Which of the following anticancer drugs exhibits dose-dependent least neurotoxicity?

Accepted Answer

Bleomycin

Answer

Cisplatin

Answer

Doxorubicin

Answer

Vinblastine

Anticancer Drugs — MCQs

Anticancer Drugs — MCQs

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