That was his third victory. The first came when he beat malignant melanoma nearly 40 years ago. In 2003, a year before his first run for the U.S. Senate, he had surgery and chemotherapy to treat colon cancer.
Coburn, a physician, is serving his second and final term in the U.S. Senate. Several colleagues tweeted prayers and wishes to him after hearing about his cancer.
It's been a tough few weeks for Oklahoma's senators.
Sen. Jim Inhofe, R-Tulsa, returned to Washington on Monday after recovering from quadruple bypass surgery.
Inhofe, 78, resumed his regular schedule, attending a hearing on natural gas drilling Tuesday.