Cancer Chemotherapy
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Questions and Answers

What is the purpose of adjuvant chemotherapy?

  • To maintain remission in cancer patients
  • To attack micro metastases after surgery or radiation (correct)
  • To provide supplemental treatment during radiation therapy
  • To shrink the cancer prior to surgery

    • What is a common resistance mechanism developed by tumor cells against chemotherapy drugs?

  • Increased activation of the drug
  • Enhanced drug uptake
  • Reduced target enzyme concentration
  • Decreased accumulation of drug (correct)

    • How is drug dosage usually calculated for chemotherapy treatment?

  • On the basis of body surface area (correct)
  • By patient's age
  • According to the patient's weight
  • Based on the type of cancer

    • Which process contributes to the toxicity of chemotherapy in normal rapidly dividing cells?

    <p>Chemotherapy-induced cell cycle arrest</p> Signup and view all the answers

    What type of kinetics is followed in the destruction of cancer cells by chemotherapeutic agents?

    <p>First-order kinetics</p> Signup and view all the answers

    How does resistance to chemotherapy commonly develop?

    <p>Long-term, continuous use</p> Signup and view all the answers

    Why is combination chemotherapy more successful than single-drug treatment?

    <p>It targets different molecular sites and mechanisms of action simultaneously</p> Signup and view all the answers

    What is a characteristic of most chemotherapeutic agents' therapeutic index?

    <p>Narrow therapeutic index</p> Signup and view all the answers

    Which of the following is an adverse effect commonly associated with chemotherapy?

    <p>Stomatitis</p> Signup and view all the answers

    When are agents with similar dose-limiting toxicities combined safely during chemotherapy treatment?

    <p>By reducing the doses of each agent</p> Signup and view all the answers

    In which cells does chemotherapy toxicity often manifest due to their rapid proliferation?

    <p>Bone marrow cells</p> Signup and view all the answers

    In which type of cancers is neo-adjuvant chemotherapy typically given?

    <p>Breast and colorectal cancers</p> Signup and view all the answers

    What is the primary mechanism of action of methotrexate (MTX) in cancer chemotherapy?

    <p>Acts as an antagonist of folic acid by inhibiting dihydrofolate reductase (DHFR)</p> Signup and view all the answers

    What is the enzyme that converts folic acid to its active, coenzyme form, tetrahydrofolic acid (FH4)?

    <p>Dihydrofolate reductase (DHFR)</p> Signup and view all the answers

    Apart from inhibiting DHFR, what other enzyme does pemetrexed inhibit?

    <p>Thymidylate synthase</p> Signup and view all the answers

    Which drug is primarily utilized in non-small cell lung cancer?

    <p>Pemetrexed</p> Signup and view all the answers

    What is the role of leucovorin in relation to MTX inhibition?

    <p>Replenishes THF pool and bypasses MTX inhibition sites</p> Signup and view all the answers

    Which type of lymphoma is pralatrexate primarily used to treat?

    <p>T-cell lymphoma</p> Signup and view all the answers

    What is the mechanism of action of 5-FU in inhibiting DNA synthesis?

    <p>Competing with thymidylate synthase</p> Signup and view all the answers

    How does 5-FU produce its anticancer effect?

    <p>Acting during the S phase of the cell cycle</p> Signup and view all the answers

    What is the main reason behind administering 5-FU intravenously?

    <p>Avoiding severe gastrointestinal toxicity</p> Signup and view all the answers

    Which enzyme's elevated levels can lead to increased 5-FU catabolism?

    <p>Dihydropyrimidine dehydrogenase (DPD)</p> Signup and view all the answers

    What can be a severe side effect in patients with DPD deficiency upon 5-FU administration?

    <p>Pancytopenia</p> Signup and view all the answers

    How is 5-FU eventually removed from the body following metabolism?

    <p>Converted to fluoro-β-alanine and excreted in urine</p> Signup and view all the answers

    What is the mechanism of action of Ara-CTP?

    <p>Inhibits DNA polymerase and terminates chain elongation</p> Signup and view all the answers

    Why is Cytarabine not effective when given orally?

    <p>It undergoes deamination to a noncytotoxic metabolite by cytidine deaminase</p> Signup and view all the answers

    What is the main mechanism of action of Azacitidine?

    <p>Activation to azacitidine triphosphate and inhibition of RNA processing</p> Signup and view all the answers

    Which cancer type is Gemcitabine commonly used for?

    <p>Pancreatic cancer</p> Signup and view all the answers

    What is the fate of both cytarabine and ara-U in the body after metabolism?

    <p>Excretion in urine</p> Signup and view all the answers

    Why is Ara-CTP considered S-phase specific in its action?

    <p>It inhibits DNA polymerase and terminates chain elongation</p> Signup and view all the answers

    What enzyme catalyzes the hydrolysis of capecitabine to 5-FU?

    <p>Thymidine phosphorylase</p> Signup and view all the answers

    Which enzyme is primarily inhibited by 5-FU, and subsequently by capecitabine?

    <p>Thymidylate synthase</p> Signup and view all the answers

    Which enzyme is responsible for the sequential phosphorylation of cytarabine in cells?

    <p>Deoxycytidine kinase</p> Signup and view all the answers

    Which cancer type is Gemcitabine primarily used for?

    <p>Lung cancer</p> Signup and view all the answers

    What is the major clinical use of cytarabine?

    <p>Leukemia</p> Signup and view all the answers

    What is the nucleotide form of cytarabine that exerts cytotoxic effects?

    <p>Cytosine arabinoside triphosphate</p> Signup and view all the answers

    Which enzyme is concentrated primarily in tumors and catalyzes the final step in converting capecitabine to 5-FU?

    <p>Thymidine phosphorylase</p> Signup and view all the answers

    What is the mechanism of action for cytarabine in treating acute nonlymphocytic leukemia?

    <p>Sequential phosphorylation by deoxycytidine kinase</p> Signup and view all the answers

    Which enzyme is NOT directly involved in the enzymatic reactions converting capecitabine to 5-FU?

    <p>Thymidylate synthase</p> Signup and view all the answers

    What is the cytotoxic form of cytarabine needed to exert its pharmacological effects?

    <p>Cytosine arabinoside triphosphate</p> Signup and view all the answers

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