Anticancer Drugs — MCQs

Anticancer Drugs Indian Medical PG Practice Questions and MCQs

Question 531: Radiosensitizers are all Except

A. Metronidazole
B. Nimorazole
C. Cisplatin
D. Amifostine (Correct Answer)

Explanation: ***Amifostine*** - Amifostine is a **radioprotector**, meaning it helps protect healthy tissues from the damaging effects of radiation. - It does this by selectively scavenging **free radicals** in normal cells, reducing radiation-induced toxicity. *Metronidazole* - **Metronidazole** is a well-known **radiosensitizer**, particularly effective in hypoxic (low-oxygen) tumor environments. - It enhances the effectiveness of radiation therapy by forming **toxic free radicals** when metabolized in hypoxic cells, thereby increasing DNA damage. *Nimorazole* - **Nimorazole** is another **nitroimidazole radiosensitizer**, similar in action to metronidazole. - It is used to improve the outcome of radiation therapy in certain cancers, especially in **hypoxic tumors**, by increasing their sensitivity to radiation. *Cisplatin* - **Cisplatin** is a platinum-based **chemotherapeutic agent** that also acts as a potent **radiosensitizer**. - It enhances the cytotoxic effects of radiation by interfering with **DNA repair mechanisms** and inducing DNA damage more effectively when combined with radiation.

Question 532: Leucovorin is used for side effect reduction in which anticancer drug?

A. Cisplatin
B. 5-FU
C. Adriamycin
D. Methotrexate (Correct Answer)

Explanation: ***Methotrexate*** - **Leucovorin rescue** is a critical adjunct therapy for **methotrexate** to prevent severe toxicity. - Methotrexate is a **folate antagonist**, and leucovorin (folinic acid) provides a reduced folate form that bypasses the blocked enzyme, restoring normal cellular function and protecting healthy cells. - This is true **"rescue therapy"** - leucovorin protects normal cells from methotrexate toxicity. *Cisplatin* - **Cisplatin** is a platinum-based chemotherapy drug primarily associated with **nephrotoxicity** and **ototoxicity**. - Its side effects are managed with **hydration, amifostine**, and antiemetics, not leucovorin. *5-FU* - **5-FU (5-fluorouracil)** is a pyrimidine analog that can cause severe **myelosuppression** and **gastrointestinal toxicity**. - While leucovorin is used WITH 5-FU (e.g., in colorectal cancer regimens), it serves to **enhance/potentiate** 5-FU's cytotoxic effect through biochemical modulation, NOT to rescue from toxicity. - This is the key distinction: leucovorin + 5-FU = **potentiation**; leucovorin + methotrexate = **rescue**. *Adriamycin* - **Adriamycin (doxorubicin)** is an **anthracycline antibiotic** known for causing **cardiotoxicity** and **myelosuppression**. - **Dexrazoxane** is used to prevent Adriamycin-induced cardiotoxicity, not leucovorin.

Question 533: Which of the following statements is not true about tamoxifen?

A. It can cause endometrial carcinoma.
B. Tamoxifen is useful in post-menopausal and aromatase inhibitors in premenopausal patients. (Correct Answer)
C. It is used for visceral metastasis.
D. Dose is 20 mg for 5 years.

Explanation: ***Tamoxifen is useful in post-menopausal and aromatase inhibitors in premenopausal patients.*** - This statement is **incorrect** because **tamoxifen** is typically used in both pre- and post-menopausal women with **hormone receptor-positive breast cancer**, acting as a **selective estrogen receptor modulator (SERM)** [1]. - **Aromatase inhibitors** are primarily used in **post-menopausal women** because they block the peripheral conversion of androgens to estrogens, a process which is the primary source of estrogen in post-menopausal women, unlike pre-menopausal women where ovaries produce significant estrogen. *It can cause endometrial carcinoma.* - This statement is **true** because tamoxifen acts as an **estrogen agonist** in the uterus, which can lead to **endometrial hyperplasia** and increase the risk of **endometrial carcinoma** [1]. - This side effect is a significant consideration, especially with **long-term use** and in **post-menopausal women** [1]. *It is used for visceral metastasis.* - This statement is **true** as tamoxifen is an effective endocrine therapy for **hormone-sensitive breast cancer**, including those with **visceral metastases** [1]. - Its systemic action helps control disease progression in various organs affected by metastatic spread. *Dose is 20 mg for 5 years.* - This statement is **true** as the standard dose of tamoxifen for the adjuvant treatment of **hormone receptor-positive breast cancer** is indeed **20 mg daily for 5 years** [1]. - In some cases, treatment may be extended up to 10 years for additional benefit, but 5 years is the commonly recommended initial duration [1].

Question 534: Which of the following drugs act by inhibiting DNA replication?

A. Mitomycin C
B. 6-Mercaptopurine (Correct Answer)
C. Actinomycin D
D. Asparaginase

Explanation: ***6-Mercaptopurine*** - This drug is a **purine analog** that acts as an **antimetabolite**, directly interfering with the **synthesis of purine nucleotides** required for DNA replication. - By inhibiting enzymes like **PRPP amidotransferase** and getting incorporated into DNA as a fraudulent nucleotide, it blocks the **de novo synthesis** pathway, preventing normal DNA replication. - This represents **direct inhibition of DNA synthesis** at the nucleotide building block level. *Mitomycin C* - This agent is an **alkylating agent** that **cross-links DNA** strands, causing DNA damage that prevents strand separation. - While it does prevent DNA replication, its mechanism is through **DNA damage and structural disruption** rather than inhibition of the DNA synthesis machinery itself. - It acts by damaging already-formed DNA rather than preventing new DNA synthesis. *Actinomycin D* - Actinomycin D is an **intercalating agent** that inserts itself between DNA base pairs, primarily **inhibiting RNA synthesis** by blocking RNA polymerase movement. - While it binds to DNA, its primary therapeutic action is on **transcription (RNA synthesis)**, not direct inhibition of DNA replication. *Asparaginase* - Asparaginase is an enzyme that **depletes asparagine** from the blood, which is an essential amino acid for certain cancer cells (e.g., leukemic cells). - Its mechanism is to starve cancer cells of asparagine, leading to **inhibition of protein synthesis**, not DNA replication.

Question 535: Which antineoplastic agent is known to cause hemorrhagic cystitis?

A. Cyclophosphamide (Correct Answer)
B. Methotrexate
C. Cisplatin
D. Vincristine

Explanation: ***Cyclophosphamide*** - Cyclophosphamide is an **alkylating agent** that forms highly reactive metabolites, such as **acrolein**, which is excreted in the urine and causes direct irritation and damage to the bladder urothelium, leading to **hemorrhagic cystitis**. - This toxicity can be mitigated by co-administration of **mesna** (2-mercaptoethane sulfonate sodium), which inactivates acrolein in the bladder, and aggressive intravenous hydration. *Methotrexate* - Methotrexate is a **folate antagonist** primarily known for causing **myelosuppression**, **mucositis**, and **hepatotoxicity**. - While it can cause renal toxicity at high doses due to precipitation in renal tubules, it is not typically associated with hemorrhagic cystitis. *Cisplatin* - Cisplatin is a **platinum-based chemotherapy agent** with significant **nephrotoxicity** and **ototoxicity** as its dose-limiting toxicities. - It also commonly causes profound nausea and vomiting but is not a primary cause of hemorrhagic cystitis. *Vincristine* - Vincristine is a **vinca alkaloid** that interferes with microtubule formation, primarily known for causing **peripheral neuropathy** (e.g., foot drop, paresthesias, constipation due to autonomic neuropathy) and is a vesicant. - It does not typically cause hemorrhagic cystitis; its bone marrow toxicity is generally less severe compared to other chemotherapeutic agents.

Question 536: Which of the following drugs is not associated with significant cardiotoxicity?

A. 5-Fluorouracil
B. Cyclophosphamide
C. Doxorubicin
D. Cisplatin (Correct Answer)

Explanation: ***Cisplatin*** - While cisplatin is associated with various toxicities, including **nephrotoxicity** and **neurotoxicity**, significant **cardiotoxicity** (like cardiomyopathy or severe arrhythmias) is much less common compared to the other listed agents. - Its primary cardiac effects are often indirect, such as electrolyte disturbances, or less severe, making it the least cardiotoxic among the options. *5-Fluorouracil* - This drug is known to cause **coronary vasospasm**, leading to **angina** or **myocardial infarction** in some patients. - The cardiotoxicity can manifest as **ischemic events** and **arrhythmias**, particularly during or shortly after infusion. *Cyclophosphamide* - High doses of cyclophosphamide can induce **hemorrhagic myocarditis** and **congestive heart failure**, particularly in the setting of bone marrow transplantation. - It causes direct myocardial damage and can lead to rapid-onset cardiac dysfunction. *Doxorubicin* - Doxorubicin is a well-known cause of **dose-dependent cardiomyopathy**, which can lead to **irreversible heart failure**. - Its cardiotoxicity can be acute (arrhythmias, pericarditis-myocarditis syndrome) or chronic (dilated cardiomyopathy).

Question 537: Which chemotherapy drug functions by alkylating DNA, resulting in strand breaks and ultimately leading to cancer cell death?

A. Cyclophosphamide (Correct Answer)
B. Methotrexate
C. Paclitaxel
D. Vincristine

Explanation: ***Cyclophosphamide*** - **Cyclophosphamide** is an **alkylating agent** that forms covalent bonds with DNA, leading to DNA cross-linking and strand breaks. - This **DNA damage** prevents cell replication and triggers apoptosis in rapidly dividing cancer cells. *Methotrexate* - **Methotrexate** is an **antimetabolite** that inhibits **dihydrofolate reductase**, thereby blocking DNA synthesis. - Its primary mechanism is interfering with **folate metabolism**, not direct DNA alkylation. *Paclitaxel* - **Paclitaxel** is a **microtubule-stabilizing agent** that promotes microtubule assembly and prevents their disassembly. - This action blocks cell division during metaphase, but it does not involve DNA alkylation. *Vincristine* - **Vincristine** is a **vinca alkaloid** that inhibits microtubule formation by binding to tubulin. - This prevents the formation of the mitotic spindle, arresting cells in metaphase, and does not involve direct DNA modification.

Question 538: A patient receiving cisplatin for chemotherapy develops renal impairment. Which of the following drugs is least likely to cause nephrotoxicity?

A. Cisplatin
B. Carboplatin
C. Bleomycin (Correct Answer)
D. Methotrexate

Explanation: ***Bleomycin*** - **Bleomycin** is an antineoplastic agent known for its primary toxicity to the **lungs (pulmonary fibrosis)** and skin, with nephrotoxicity being very rare [1]. - Its mechanism of action involves DNA strand scission, but its elimination is primarily renal without causing significant damage to the **kidneys**. *Cisplatin* - **Cisplatin** is a highly nephrotoxic agent, causing acute tubular necrosis, and is a well-known cause of **renal impairment** in chemotherapy patients [2]. - The patient in the stem is described as receiving cisplatin and developing renal impairment, indicating its potent nephrotoxic potential. *Carboplatin* - **Carboplatin** is an analog of cisplatin and is also **nephrotoxic**, although its nephrotoxicity is generally less severe than that of cisplatin [2]. - It is still a significant concern, and regular monitoring of kidney function is required during treatment. *Methotrexate* - **Methotrexate**, especially at high doses, can cause **acute kidney injury** due to the precipitation of its metabolites in the renal tubules, leading to obstruction. - This nephrotoxicity can be mitigated by adequate hydration and **urinary alkalinization**.

Question 539: Hand and foot syndrome is caused by which of the following drugs?

A. Vincristine
B. Cisplatin
C. Azathioprine
D. 5-Fluorouracil (5-FU) (Correct Answer)

Explanation: ***5-Fluorouracil (5-FU)*** - **Hand-foot syndrome (HFS)**, also known as palmar-plantar erythrodysesthesia, is a common and dose-limiting dermatological toxicity of 5-FU. - It presents with **redness, swelling, pain, and blistering** on the palms of the hands and soles of the feet. *Vincristine* - This drug is primarily associated with **neurotoxicity**, causing peripheral neuropathy with symptoms like paresthesias, weakness, and loss of reflexes. - It does not typically cause hand-foot syndrome, which is a specific dermatological reaction. *Cisplatin* - Cisplatin is known for its **nephrotoxicity** (kidney damage), ototoxicity (hearing loss), and severe nausea and vomiting. - While it can cause some dermatological side effects, hand-foot syndrome is not a characteristic or common adverse event associated with cisplatin. *Azathioprine* - Azathioprine is an immunosuppressant often used in autoimmune diseases and transplant patients, and its main side effects include **myelosuppression** (bone marrow suppression), liver dysfunction, and gastrointestinal issues. - It is not implicated in causing hand-foot syndrome.

Question 540: A patient with breast cancer is administered a chemotherapy agent that stabilizes microtubules, preventing their disassembly during mitosis. Which drug is used?

A. Doxorubicin
B. Cyclophosphamide
C. Paclitaxel (Correct Answer)
D. Vincristine

Explanation: ***Paclitaxel*** - **Paclitaxel** is a **taxane** drug that works by binding to **beta-tubulin subunits**, stabilizing microtubules and preventing their depolymerization. - This stabilization arrests cells in the **G2/M phase of mitosis**, leading to apoptotic cell death in rapidly dividing cancer cells. *Doxorubicin* - **Doxorubicin** is an **anthracycline antibiotic** that intercalates into DNA, leading to strand breaks and inhibition of **topoisomerase II**. - Its primary mechanism is DNA damage, not direct microtubule stabilization. *Cyclophosphamide* - **Cyclophosphamide** is an **alkylating agent** that forms covalent bonds with DNA, causing cross-linking and strand breaks. - This DNA damage interferes with replication and transcription, leading to cell cycle arrest and apoptosis. *Vincristine* - **Vincristine** is a **vinca alkaloid** that binds to **tubulin dimers**, preventing their polymerization into microtubules. - Unlike paclitaxel, which stabilizes microtubules, vincristine inhibits their formation and promotes disassembly.

Practice by Chapter

Principles of Cancer Chemotherapy

Practice Questions

Alkylating Agents

Practice Questions

Antimetabolites

Practice Questions

Antitumor Antibiotics

Practice Questions

Plant Alkaloids

Practice Questions

Topoisomerase Inhibitors

Practice Questions

Hormonal Agents

Practice Questions

Targeted Therapy

Practice Questions

Immunotherapy

Practice Questions

Management of Chemotherapy Side Effects

Practice Questions

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