Former Minnesota Sen. Norm Coleman is battling throat cancer.

Coleman shared his diagnosis Monday on his Facebook page. He says his doctors in the Twin Cities and the Mayo Clinic say the cancer is treatable and the prognosis is "extremely positive."

Reached by phone, Coleman says he isn't commenting beyond the social media post that recounts initial shock and fear about the diagnosis. The 66-year-old says he sought an assessment after experiencing a prolonged sore throat and noticing a lump on his throat.

The Republican Coleman is former mayor of St. Paul and served one term in the Senate.

Coleman remains active in political and legal circles in Minnesota and Washington. He says he plans to remain visible while undergoing treatment.