Sen. John McCain has decided to stop his brain cancer treatment, his family announced Friday morning.

“Last summer, Senator John McCain shared with Americans the news our family already knew: he had been diagnosed with an aggressive glioblastoma, and the prognosis was serious. In the year since, John has surpassed expectations for his survival,” the family said. “But the progress of disease and the inexorable advance of age render their verdict. With his usual strength of will, he has now chosen to discontinue medical treatment.”

[John McCain’s Life on the Hill in Photos]

McCain, an Arizona Republican and the chairman of the Senate Armed Services Committee, has been absent from the Senate since last December, while undergoing treatment in his home state.

“Our family is immensely grateful for the support and kindness of all his caregivers over the last year, and for the continuing outpouring of concern and affection from John’s many friends and associates, and the many thousands of people who are keeping him in their prayers. God bless and thank you all,” the McCain family said.