Sen. Tom Coburn, R-Okla., is undergoing treatment and evaluation after a recurrence of prostate cancer, a spokesman for Coburn confirmed to ABC News.
In 2011, Coburn, now 65, underwent surgery to treat an early stage incidence of prostate cancer.
Coburn has been treated for cancer two other times. He had malignant melanoma in 1975 and colon cancer in 2001.
This was first reported by NewsOK.com.
Last month, Oklahoma's other senator, Republican Jim Inhofe, underwent quadruple bypass surgery.