BSD Medical Corp. has received approval of an "investigational device" exemption from the Food and Drug Administration to test a hyperthermia system in the treatment of cancerous tumors with controlled heat from microwave, radio-frequency and ultrasound energy sources.

The FDA approval is a first step toward gaining pre-market approval from the FDA for full-scale marketing of the system in the United States.Studies involving the treatment of deep-seated human tumors with a hyperthermia system will begin soon at the Kenneth Norris Jr. Cancer Hospital and Research Institute of the University of Southern California; Duke University Medical Center; the Mallinckrodt Institute of Radiology, St. Louis; and Park View Medical Center in Nashville, Tennessee.

Alan L. Himber, chairman of BSD, also announced that some of his private investment partnerships have purchased all of the outstanding shares of the company's Series A and B preferred stock along with warrants to purchase large blocks of company stock.