American Board of Internal Medicine (ABIM) Certification Practice Exam

When should doxorubicin therapy be discontinued in adults?

1. After 1 year of therapy

2. If signs of liver failure appear

3. If there is evidence of heart failure

4. When a 5% decline in ejection fraction is noted

The correct answer is: If there is evidence of heart failure

Doxorubicin is an anthracycline chemotherapy agent that is known for its efficacy in treating various cancers but also carries the risk of cardiotoxicity, which can manifest as heart failure. The appropriate discontinuation of doxorubicin therapy is crucial when there is evidence of heart failure. Evidence of heart failure indicates that the heart's ability to pump adequately has been compromised, which can be a direct result of the cumulative cardiotoxic effects of doxorubicin. This can lead to serious complications and potentially irreversible damage to the heart muscle. Therefore, the presence of clinical signs consistent with heart failure serves as a critical threshold that necessitates stopping the treatment to protect the patient from further cardiac injury. In contrast, other options such as a specific duration of therapy (like 1 year) or the observation of liver failure do not directly relate to the cardiotoxic risks associated with doxorubicin and would not be sufficient reasons to discontinue this therapy. Similarly, a 5% decline in ejection fraction, while important, is not the definitive threshold for stopping therapy; the clinical presentation of actual heart failure represents a more urgent and serious indication for discontinuation. In summary, discontinuing doxorubicin therapy upon evidence of heart failure is