Which factor increases the risk of cardiotoxicity with doxorubicin therapy?

• A. Elevated baseline alkaline phosphatase
• B. Younger age at treatment
• C. Short infusion duration
• D. Cumulative lifetime dose

Answer: (D)

The main factor driving doxorubicin-induced cardiotoxicity is the total amount the heart has been exposed to over time—the cumulative lifetime dose. The heart suffers progressive damage as the drug accumulates, mainly through mechanisms like generation of reactive oxygen species and mitochondrial injury in cardiomyocytes. As the cumulative dose rises, the risk of developing cardiomyopathy and heart failure increases, with a threshold beyond which risk climbs sharply. This is why clinicians closely track cumulative dose (often expressed as mg/m^2) and may limit it or switch to alternative strategies or cardioprotectants when approaching that limit.

Elevated baseline alkaline phosphatase isn’t related to cardiac toxicity, and while some factors like age can influence risk in certain contexts, the strongest, most consistent predictor is how much doxorubicin the patient has received overall. Shorter infusion duration can alter peak drug levels acutely but does not determine the long-term, dose-dependent risk in the same way that the total cumulative exposure does.