Doxorubicin is considered one of the strongest chemotherapy drugs for breast cancer ever invented. It can kill cancer cells at every point in their life cycle, and it's used to treat a wide variety of cancers, not just breast cancer. Doxorubicin is also known as “The Red Devil” because it is a clear bright red color. It can cause your urine or other body fluids to turn a reddish color for 1 to 2 days after a dose is given, which is normal and temporary.