South Dakota U.S. Sen. Mike Rounds says his wife Jean is beginning treatment for cancer.

Rounds, a Republican, said in a prepared statement Tuesday that Jean Rounds was diagnosed with “a malignant high-grade aggressive tumor” after tests over several weeks. The statement said Jean Rounds’ tumor was near her sciatic nerve.

The statement said Jean Rounds, 62, will undergo treatment at Mayo Clinic in Rochester, Minnesota, starting this week.

Rounds said Jean Rounds is “resilient and strong” and that the family is grateful for prayers in her behalf.

Rounds is up for re-election in 2020.