Senate Armed Services Committee Chairman John McCain will not return home to Arizona for his extended brain cancer treatment, and will instead undergo radiation and chemotherapy near Washington, D.C., "while maintaining a regular work schedule" in Congress.

McCain spokeswoman Julie Tarallo announced the decision on Tuesday as McCain oversaw the Senate's debate and consideration of the fiscal 2018 defense authorization bill, which sets spending levels for the Pentagon and other national security accounts.

"Senator McCain received an MRI at the National Institutes of Health (NIH) in Bethesda, Maryland yesterday," Tarallo said. "Following the advice of his doctors, Senator McCain will continue to receive targeted radiation and chemotherapy treatments at NIH while maintaining a regular work schedule in the United States Senate."

McCain had originally planned to receive treatment at the Mayo Clinic in Phoenix.