Sen. John McCain, R-Ariz., will return to the U.S. Senate next week as Congress starts a new legislative season.

McCain, who turned 81 on Tuesday, is looking "forward to continuing his work for the people of Arizona and the nation," according to a statement from his office.

McCain has been receiving treatment for brain cancer and according to his daughter, Meghan McCain, completed his first round of chemotherapy two weeks ago.

As Senate Armed Services chairman, McCain will lead the chamber's debate on the National Defense Authorization Act.