Which feature best distinguishes doxorubicin-induced cardiomyopathy from trastuzumab-induced cardiomyopathy?
- A Doxorubicin injury is cumulative-dose dependent and often irreversible, while trastuzumab injury is less dose-dependent and frequently reversible on withdrawal ✓
- B Trastuzumab injury is dose-dependent and typically irreversible, while doxorubicin injury recovers fully on stopping the drug
- C Both produce identical histological changes and identical rates of functional recovery
- D Trastuzumab acts through topoisomerase II-beta inhibition, producing free-radical mediated myocyte death
Correct answer: A. Doxorubicin injury is cumulative-dose dependent and often irreversible, while trastuzumab injury is less dose-dependent and frequently reversible on withdrawal
Explanation
Anthracyclines cause Type I cardiotoxicity: free-radical mediated myocyte death via topoisomerase II-beta, cumulative-dose dependent, with risk persisting years and often irreversible loss of myocytes. Trastuzumab causes Type II injury, generally not dose-dependent and more often reversible after withdrawal because myocytes are stunned rather than killed. Option B reverses the two drugs. Option D describes anthracycline, not trastuzumab, mechanism. This distinction drives why dexrazoxane is used to protect against anthracycline, not trastuzumab, toxicity.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
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