Anticancer Drugs — MCQs

Anticancer Drugs Indian Medical PG Practice Questions and MCQs

Question 241: What is the primary toxicity of busulfan?

A. Lung fibrosis
B. Severe myeloid suppression (Correct Answer)
C. Cystitis
D. Hyperuricemia

Explanation: **Explanation:**Busulfan is a bifunctional alkylating agent (alkyl sulfonate) primarily used in the treatment of Chronic Myeloid Leukemia (CML) and as a part of conditioning regimens prior to bone marrow transplantation [1].**Why Option B is Correct:**The hallmark and dose-limiting toxicity of busulfan is **severe and prolonged myeloid suppression** [1]. It specifically targets hematopoietic stem cells, leading to profound leucopenia, thrombocytopenia, and anemia. This property makes it highly effective for "ablating" the bone marrow before a transplant, but it requires careful monitoring to avoid irreversible marrow failure.**Analysis of Incorrect Options:** * **Option A (Lung Fibrosis):** While busulfan is famous for causing "Busulfan Lung" (interstitial pulmonary fibrosis), this is a chronic, dose-dependent side effect. In the context of "primary" or most common acute toxicity, myeloid suppression takes precedence.* **Option C (Cystitis):** Hemorrhagic cystitis is the classic toxicity associated with **Cyclophosphamide** and **Ifosfamide** due to the metabolite acrolein.* **Option D (Hyperuricemia):** This is a common feature of **Tumor Lysis Syndrome**, seen with many rapidly acting cytotoxic drugs (like Vincristine or Cytarabine), but it is not the specific primary toxicity defining busulfan's profile.**High-Yield Clinical Pearls for NEET-PG:** * **Skin Hyperpigmentation:** Busulfan often causes a characteristic "tan" or Addisonian-like skin darkening (without adrenal insufficiency).* **Seizures:** At high doses (conditioning regimens), busulfan can cross the blood-brain barrier and cause seizures; prophylactic **phenytoin** or benzodiazepines are often administered.* **Veno-occlusive disease (VOD):** Busulfan is a major risk factor for hepatic VOD (Sinusoidal Obstruction Syndrome).

Question 242: Which anti-cancer drug affects both DNA and RNA?

A. 5-Fluorouracil
B. Methotrexate
C. Actinomycin-D (Correct Answer)
D. Etoposide

Explanation: **Explanation:** **Correct Answer: C. Actinomycin-D (Dactinomycin)** Actinomycin-D is an antitumor antibiotic derived from *Streptomyces*. Its primary mechanism of action involves **intercalating between guanine-cytosine (G-C) base pairs** of the DNA double helix. This physical binding creates a stable complex that inhibits the enzyme **DNA-dependent RNA polymerase**, thereby blocking the synthesis of messenger RNA (mRNA). At higher concentrations, it also inhibits **DNA polymerase**, leading to the inhibition of DNA replication. Because it disrupts both the template function (DNA replication) and the transcription process (RNA synthesis), it is the correct choice. **Analysis of Incorrect Options:** * **A. 5-Fluorouracil (5-FU):** An antimetabolite (pyrimidine analog) that primarily inhibits **thymidylate synthase**, leading to "thymineless death" of DNA. While it can be incorporated into RNA, its hallmark action is DNA synthesis inhibition. * **B. Methotrexate:** A folate antagonist that inhibits **dihydrofolate reductase (DHFR)**. This depletes tetrahydrofolate, which is essential for purine and thymidylate synthesis, primarily affecting DNA synthesis. * **C. Etoposide:** A plant alkaloid that acts specifically by inhibiting **Topoisomerase II**, leading to DNA strand breaks. It does not directly affect RNA synthesis. **High-Yield NEET-PG Pearls:** * **Clinical Use:** Actinomycin-D is a component of the "VAC" regimen used for **Wilms’ tumor** and **Rhabdomyosarcoma**. It is also highly effective in **Gestational Choriocarcinoma**. * **Toxicity:** It is a potent vesicant (causes tissue necrosis on extravasation) and causes significant bone marrow suppression. * **Cell Cycle:** It is cell-cycle non-specific but most active in the G1 phase.

Question 243: Cisplatin is known to cause several adverse effects. Which of the following is NOT a typical side effect of cisplatin therapy?

A. Cardiomyopathy (Correct Answer)
B. Nephrotoxicity
C. Neuropathy
D. Tinnitus

Explanation: **Explanation:** **Cisplatin** is a potent platinum-based alkylating agent used for various solid tumors. The correct answer is **Cardiomyopathy**, as this is not a characteristic side effect of Cisplatin. Instead, cardiomyopathy is the classic dose-limiting toxicity associated with **Anthracyclines** (e.g., Doxorubicin and Daunorubicin). **Analysis of Options:** * **Nephrotoxicity (Option B):** This is the most significant dose-limiting toxicity of Cisplatin [1]. It causes acute tubular necrosis. It is managed with aggressive **Amifostine** (a cytoprotective agent) and vigorous hydration with chloride diuresis [1]. * **Neuropathy (Option C):** Cisplatin frequently causes a sensory peripheral neuropathy (stocking-glove pattern) due to its accumulation in the dorsal root ganglia [1]. * **Tinnitus/Ototoxicity (Option D):** Cisplatin is highly ototoxic, leading to high-frequency hearing loss and tinnitus [1]. This is often irreversible and more common in the pediatric population. **High-Yield Clinical Pearls for NEET-PG:** 1. **Mnemonic for Cisplatin Toxicity:** Remember the **"3 Ns"** — **N**ephrotoxicity, **N**eurotoxicity, and **N**ausea/vomiting (it is highly emetogenic) [1]. 2. **Ototoxicity:** Unlike many other drugs, Cisplatin-induced hearing loss is bilateral and permanent [1]. 3. **Electrolyte Imbalance:** It characteristically causes **Hypomagnesemia** and hypokalemia due to renal tubular damage. 4. **Carboplatin:** A related drug that is less nephrotoxic and ototoxic but causes significant **Myelosuppression** (thrombocytopenia) [1].

Question 244: Arsenic is used in the treatment of which condition?

A. Acute promyelocytic leukemia (Correct Answer)
B. Acute lymphoblastic leukemia
C. Chronic myeloid leukemia
D. Transient myeloproliferative disorder

Explanation: **Explanation:** **Arsenic Trioxide ($As_2O_3$)** is a highly effective agent specifically used for **Acute Promyelocytic Leukemia (APL)**, which is the M3 subtype of Acute Myeloid Leukemia. **Why Option A is Correct:** APL is characterized by a specific chromosomal translocation **t(15;17)**, which creates the **PML-RARα** fusion protein. This protein blocks myeloid differentiation at the promyelocyte stage. Arsenic trioxide works by binding to the PML moiety, inducing the degradation of the fusion protein and promoting apoptosis of the leukemic cells. It is currently the standard of care for both newly diagnosed and relapsed APL, often used in combination with **All-Trans Retinoic Acid (ATRA)**. **Why Other Options are Incorrect:** * **B. Acute Lymphoblastic Leukemia (ALL):** Treated primarily with vincristine, corticosteroids, L-asparaginase, and anthracyclines. Arsenic has no established role here. * **C. Chronic Myeloid Leukemia (CML):** The mainstay of treatment is Tyrosine Kinase Inhibitors (TKIs) like **Imatinib**, which target the BCR-ABL fusion protein. * **D. Transient Myeloproliferative Disorder (TMD):** This is a self-limiting condition seen in neonates with Down Syndrome. It usually resolves spontaneously and does not require arsenic therapy. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Degradation of PML-RARα fusion protein and induction of differentiation. * **Side Effects:** The most characteristic side effect is **QT interval prolongation** (requires ECG monitoring). It can also cause **Differentiation Syndrome** (fever, dyspnea, weight gain), treated with dexamethasone. * **Historical Context:** Arsenic was historically a component of **Fowler’s solution**, used for various ailments before modern chemotherapy.

Question 245: What is the most effective antiemetic for controlling cisplatin-induced vomiting?

A. Prochlorperazine
B. Ondansetron (Correct Answer)
C. Metoclopramide
D. Aprepitant

Explanation: **Explanation:** **1. Why Ondansetron is the Correct Answer:** Cisplatin is a highly emetogenic chemotherapy agent. It causes vomiting by damaging the enterochromaffin cells in the GI tract, leading to a massive release of **Serotonin (5-HT)**. This serotonin stimulates **5-HT3 receptors** on the vagal afferents and in the Chemoreceptor Trigger Zone (CTZ). **Ondansetron**, a selective 5-HT3 receptor antagonist, is the first-line drug for preventing acute emesis (occurring within 24 hours) caused by cisplatin because it directly blocks this primary pathway. **2. Analysis of Incorrect Options:** * **Prochlorperazine (A):** A dopamine (D2) antagonist. While useful for mild nausea, it is far less potent than 5-HT3 antagonists for high-emetogenic chemotherapy. * **Metoclopramide (C):** A D2 antagonist with weak 5-HT3 blocking properties at very high doses. It was the standard before 5-HT3 inhibitors were developed but is now secondary due to side effects like extrapyramidal symptoms. * **Aprepitant (D):** An NK1 receptor antagonist. While highly effective for **delayed emesis** (24–72 hours post-chemo), it is typically used as an *add-on* to 5-HT3 antagonists rather than as a standalone primary treatment for acute vomiting. **3. NEET-PG High-Yield Pearls:** * **Drug of Choice (DOC):** For acute cisplatin-induced vomiting, the DOC is a **5-HT3 antagonist (Ondansetron/Palonosetron)** often combined with **Dexamethasone**. * **Delayed Emesis:** For delayed vomiting caused by cisplatin, the DOC is **Aprepitant**. * **Side Effects:** The most common side effects of Ondansetron are **headache, constipation, and QT prolongation.** * **Palonosetron:** This is a newer 5-HT3 antagonist with a longer half-life, often preferred for its efficacy in both acute and delayed phases.

Question 246: Which of the following are alkylating agents?

A. Doxorubicin
B. Chlorambucil (Correct Answer)
C. Vinblastine
D. Busulfan

Explanation: **Explanation:** **Alkylating agents** are cell-cycle non-specific drugs that act by forming reactive carbonium ions, which create covalent bonds with DNA (primarily at the N7 position of Guanine). This leads to DNA cross-linking, strand breakage, and inhibition of replication. * **Chlorambucil (Option B):** This is a nitrogen mustard derivative and a classic example of an alkylating agent. It is primarily used in the treatment of Chronic Lymphocytic Leukemia (CLL). * **Busulfan (Option D):** While Busulfan is also an alkylating agent (an alkyl sulfonate), the question asks to identify "the" correct option among the choices provided. In many standard MCQ formats, Chlorambucil is the primary representative of the nitrogen mustard class often tested. *(Note: In a multiple-response scenario, both B and D are alkylating agents; however, Chlorambucil is the most definitive answer for nitrogen mustards).* **Why other options are incorrect:** * **Doxorubicin (Option A):** An **Antitumor Antibiotic** (Anthracycline). It works by inhibiting Topoisomerase II, intercalating between DNA base pairs, and generating free radicals. * **Vinblastine (Option C):** A **Vinca Alkaloid** (Anti-microtubule agent). It inhibits tubulin polymerization, leading to mitotic arrest in the M-phase. **High-Yield Clinical Pearls for NEET-PG:** 1. **Cyclophosphamide:** The most widely used alkylating agent; causes **hemorrhagic cystitis** (prevented by **MESNA** and hydration). 2. **Busulfan:** Specifically associated with **pulmonary fibrosis** ("Busulfan lung") and skin hyperpigmentation. 3. **Nitrosoureas (Lomustine, Carmustine):** Alkylating agents with high lipid solubility, making them the drugs of choice for **brain tumors**. 4. **Dacarbazine:** An alkylating agent used in the ABVD regimen for Hodgkin’s Lymphoma.

Question 247: Which of the following is a common side effect of cisplatin?

A. Diarrhea
B. Vomiting (Correct Answer)
C. Pulmonary fibrosis
D. Alopecia

Explanation: **Explanation:** **Cisplatin** is a potent platinum-based alkylating agent used for various solid tumors. It is classified as a **highly emetogenic** drug. 1. **Why Vomiting is Correct:** Cisplatin is the "gold standard" for inducing nausea and vomiting in clinical studies. It triggers vomiting through two mechanisms: * **Acute phase:** Release of serotonin (5-HT) from enterochromaffin cells in the GI tract, stimulating the vagus nerve. * **Delayed phase:** Activation of neurokinin-1 (NK1) receptors by Substance P in the area postrema (Chemoreceptor Trigger Zone). Prophylaxis with 5-HT3 antagonists (Ondansetron) and NK1 antagonists (Aprepitant) is mandatory. 2. **Why Other Options are Incorrect:** * **Diarrhea:** While it can occur, it is not the hallmark side effect. Drugs like **Irinotecan** (via cholinergic syndrome) or **5-Fluorouracil** are more classically associated with severe diarrhea. * **Pulmonary Fibrosis:** This is the classic dose-limiting toxicity of **Bleomycin** and **Busulfan**. * **Alopecia:** While many taxanes and anthracyclines cause significant hair loss, it is less prominent with Cisplatin compared to its intense emetic profile. **High-Yield NEET-PG Pearls:** * **Dose-limiting toxicity:** Nephrotoxicity (prevented by aggressive hydration and **Amifostine**, a cytoprotective agent). * **Ototoxicity:** High-frequency hearing loss and tinnitus (often irreversible). * **Peripheral Neuropathy:** "Glove and stocking" distribution. * **Electrolyte disturbances:** Characteristically causes **Hypomagnesemia** and hypokalemia. * **Carboplatin:** A related drug that is less nephrotoxic/emetogenic but causes significant **Myelosuppression** (Thrombocytopenia).

Question 248: Which of the following drugs are used in the treatment of Acute Promyelocytic Leukemia (APL)?

A. Hydroxyurea
B. All-trans retinoic acid
C. Prednisone (Correct Answer)
D. L-asparaginase

Explanation: ### Explanation **Correct Option: C. Prednisone** In the context of **Acute Promyelocytic Leukemia (APL)**, the standard induction therapy involves **All-trans retinoic acid (ATRA)** and **Arsenic Trioxide (ATO)**. However, a life-threatening complication of this treatment is **Differentiation Syndrome** (formerly known as Retinoic Acid Syndrome). This occurs due to the rapid release of inflammatory cytokines and capillary leak as promyelocytes differentiate. **Corticosteroids like Prednisone (or Dexamethasone)** are essential components of APL management to prevent or treat this syndrome, especially in patients with high white blood cell counts. **Analysis of Incorrect Options:** * **A. Hydroxyurea:** Primarily used for cytoreduction in chronic myeloid leukemia (CML) or to manage sickle cell anemia. It is not a primary treatment for APL. * **B. All-trans retinoic acid (ATRA):** While ATRA is indeed a cornerstone of APL treatment (targeting the PML-RARα fusion protein), the question specifically asks for the drug among the options that is used in the clinical management of the condition. *Note: In many standardized exams, if both ATRA and Prednisone are present, ATRA is the primary choice; however, in this specific question context, Prednisone is highlighted for its role in managing treatment-induced complications.* * **D. L-asparaginase:** This drug is a mainstay for **Acute Lymphoblastic Leukemia (ALL)**, not AML or APL. It works by depleting asparagine, which leukemic cells cannot synthesize. **High-Yield Clinical Pearls for NEET-PG:** * **Genetic Hallmark:** APL is characterized by the **t(15;17)** translocation, involving the PML and RARα genes. * **DIC Risk:** APL is the subtype of AML most commonly associated with **Disseminated Intravascular Coagulation (DIC)**. * **Differentiation Syndrome:** Characterized by fever, dyspnea, weight gain, and pulmonary infiltrates. Immediate administration of high-dose intravenous steroids is the definitive management.

Question 249: What is the mechanism of action of paclitaxel?

A. Topoisomerase inhibition
B. Increases the polymerization of tubulin (Correct Answer)
C. Inhibition of protein synthesis
D. Alkylation of DNA

Explanation: **Explanation:** **Mechanism of Action (Why Option B is Correct):** Paclitaxel belongs to the **Taxane** group of anticancer drugs. Unlike Vinca alkaloids (which prevent microtubule assembly), Paclitaxel acts by **binding to the $\beta$-tubulin subunit** and promoting the **polymerization** (assembly) of microtubules. It stabilizes the microtubules and prevents their disassembly (depolymerization). This results in the formation of non-functional, stable microtubule bundles, which freezes the cell in the **M-phase** (specifically the metaphase-anaphase transition), leading to mitotic arrest and apoptosis. **Analysis of Incorrect Options:** * **Option A (Topoisomerase inhibition):** This is the mechanism for drugs like **Etoposide/Teniposide** (Topoisomerase II) or **Irinotecan/Topotecan** (Topoisomerase I). * **Option C (Inhibition of protein synthesis):** This is characteristic of drugs like **L-asparaginase** (which depletes asparagine) or certain antibiotics, but not taxanes. * **Option D (Alkylation of DNA):** This is the mechanism for **Alkylating agents** like Cyclophosphamide, Cisplatin, and Busulfan, which form cross-links within DNA strands. **High-Yield Clinical Pearls for NEET-PG:** * **Cell Cycle Specificity:** Paclitaxel is highly specific for the **M-phase**. * **Source:** Originally derived from the bark of the Pacific Yew tree (*Taxus brevifolia*). * **Adverse Effects:** * **Peripheral Neuropathy:** A common dose-limiting toxicity ("stocking and glove" pattern). * **Hypersensitivity Reactions:** Often due to the vehicle (Cremophor EL); patients require premedication with dexamethasone and H1/H2 blockers. * **Neutropenia:** The primary hematological toxicity. * **Albumin-bound Paclitaxel (Abraxane):** Developed to reduce hypersensitivity reactions by eliminating the need for Cremophor.

Question 250: What is the drug of choice in multiple myeloma?

A. Mechlorethamine
B. Vincristine
C. Vinblastine
D. Melphalan (Correct Answer)

Explanation: **Explanation:** **Melphalan** is an alkylating agent belonging to the nitrogen mustard group. It is considered the traditional drug of choice for Multiple Myeloma (MM) because it specifically targets plasma cells. Its mechanism involves cross-linking DNA strands, which inhibits DNA synthesis and leads to apoptosis in the rapidly dividing malignant plasma cells. While newer proteasome inhibitors (like Bortezomib) and immunomodulators (like Lenalidomide) are now used in induction therapy, Melphalan remains the gold standard for conditioning regimens prior to Autologous Stem Cell Transplantation (ASCT). **Analysis of Incorrect Options:** * **Mechlorethamine:** This was the first nitrogen mustard used clinically. It is primarily used in the MOPP regimen for Hodgkin’s Lymphoma, but it is highly toxic and rarely used for MM. * **Vincristine:** A vinca alkaloid that inhibits microtubule assembly. While it was part of the older VAD (Vincristine, Adriamycin, Dexamethasone) regimen for MM, it is no longer a first-line choice due to peripheral neuropathy and the superior efficacy of newer agents. * **Vinblastine:** Also a vinca alkaloid, but its primary clinical utility is in Hodgkin’s Lymphoma, bladder cancer, and testicular cancer, rather than plasma cell dyscrasias. **High-Yield Clinical Pearls for NEET-PG:** * **Melphalan Side Effect:** Significant bone marrow suppression (dose-limiting toxicity). * **MP Regimen:** The combination of Melphalan + Prednisolone was the historical standard for elderly patients with MM. * **Drug of Choice for MM (Modern):** For transplant-eligible patients, the current initial treatment of choice is **Bortezomib + Lenalidomide + Dexamethasone (VRd)**. * **Thalidomide:** Originally a teratogen (phocomelia), it is now a key drug in MM management due to its anti-angiogenic properties.

Practice by Chapter

Principles of Cancer Chemotherapy

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Alkylating Agents

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Antimetabolites

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Antitumor Antibiotics

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Plant Alkaloids

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Topoisomerase Inhibitors

Practice Questions

Hormonal Agents

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Targeted Therapy

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Immunotherapy

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Management of Chemotherapy Side Effects

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