Sen. Bob Casey (D-Pa.) announced Thursday that he was diagnosed last month with prostate cancer, noting he has an "excellent prognosis."

Driving the news: "In the coming months I will undergo surgery, after which I am expected to make a full recovery," he said in a tweet.

• "I am confident that my recommended course of treatment will allow me to continue my service in the 118th Congress with minimal disruption, and I look forward to the work ahead," he said.
• "While this news came as a shock, I can report that I have an excellent prognosis, as well as the benefit of exceptional medical care and the unwavering support of my family," he also said.

The big picture: Casey is one of two Democrats from Pennsylvania in the U.S. Senate after Sen. John Fetterman (D-Pa.) was sworn in this week.

Editor's note: This is a developing story. Please check back for updates.