Methods and for treatment of cancer and other diseases including complications from late stage viral infections by inducing hyperthermia in a patient relying on withdrawing blood from the patient and returning the withdrawn blood to the patient to establish an extracorporeal flow circuit. Blood is heated by passing through the extracorporeal circuit at a controlled rate until a target body core temperature in is achieved. Usually, the blood will be subjected to a continuously re-circulating dialysis to balance electrolytes. Additionally, the blood will be subjected to a continuously recirculating regeneration through a carbon sorbent column where toxins and contaminants are removed. The blood temperature is maintained at the target blood temperature for a treatment period, and the blood is cooled after the treatment period has been completed. The method can also be effective in treating rheumatoid arthritis, scleroderma, hepatitis, sepsis, the Epstein-Barr virus, and patients with life threatening complications from other viruses, including the COVID-19 virus. A method for removing viruses from the blood supply in an external circuit is also presented.