According to some embodiments, a system may treat blood outside the body of a patient. The system may include one or more pumps configured to draw blood from a patient into a fluid flow path at a rate, for example, of 5-7 liters per minute. The system may include one or more heat exchangers coupled to the fluid flow path and configured to heat the blood, for example, to a temperature above 42 degrees Celsius and below 43.2 degrees Celsius.