John McCain completes first round of radiation, chemotherapy treatment

"His resilience & strength is incredible," daughter Meghan McCain tweeted.

"My father completed first round radiation/chemo," she tweeted. "His resilience & strength is incredible. Fight goes on, here's to small wins. #f***cancer"

In a statement released July 28, his office said, "In accordance with the guidance of his physicians, Senator McCain is returning to Arizona to undergo further treatment at Mayo Clinic. On Monday, July 31, he will begin a standard post-surgical regimen of targeted radiation and chemotherapy. During that time, Senator McCain will maintain a work schedule. He plans to return to Washington at the conclusion of the August recess."

Shortly after his daughter tweeted the update on his treatment, Sen. McCain on Friday tweeted a photo with staff at the Mayo Clinic, writing, "Thank you to the wonderful team @MayoClinic - we appreciate everything you do!"