What is the upper limits of anthracycline dose you are willing to give in a treatment-refractory metastatic breast cancer patient if the patient is responding to salvage weekly adriamycin after progression on multiple prior regimens?

I would not normally exceed 350-400 mg/m2. However, this is a tough situation in that the patient is treatment-refractory without many other great options and responding. According to the package insert, "the probability of developing impaired myocardial function based on a combined index of signs, symptoms and decline in left ventricular ejection fraction (LVEF) is estimated to be 1 to 2% at a total cumulative dose of 300 mg/m2 of doxorubicin, 3 to 5% at a dose of 400 mg/m2, 5 to 8% at 450 mg/m...