Sen. John McCain's mother Roberta is aware that her son is stopping treatment for stage-four brain cancer, PEOPLE has learned

Sen. John McCain‘s mother Roberta is aware that her son is stopping treatment for stage-four brain cancer, PEOPLE has learned.

“Roberta is 106, but she’s spunky,” a close family friend exclusively tells PEOPLE. “She knows he is ill.”

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On Friday, the McCain family announced that the 81-year-old politician — who was diagnosed with glioblastoma, an aggressive brain cancer with a median survival rate of just 15 months, in July 2017 — made the decision to stop treatment.

“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,” the statement said. “In the year since, John has surpassed expectations for his survival. 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.”

“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 associated, and the many thousands of people who are keeping him in their prayers,” the statement continued. “God bless and thank you all.”

Image zoom Roberta and John McCain Alex Wong/Getty

To mark Roberta’s 106th birthday on Feb. 7, Sen. McCain, his wife Cindy and their daughter Meghan shared heartfelt messages on social media about the centenarian’s impact on their lives.

Sen. McCain tweeted a video filled with photos of his mother over the years, writing, “Happy 106th birthday to my wonderful mother Roberta – we love you mom!”

“Happy 106th Birthday to my lovely mother in-law Roberta McCain,” Cindy, 64, wrote on Twitter. “You are a true inspiration.”

“Happy 106th birthday to my incredible Nana McCain,” wrote Meghan, 33, on Instagram and Twitter, captioning a photo of the two. “You are an inspiration to me and so many others! I love you dearly.”

Image zoom Roberta McCain Matt Rourke/AP/REX/Shutterstock

Roberta has been a vocal supporter of her son’s political efforts over the years. At 96 years old, during her son’s 2008 presidential campaign, she gave a speech to campaign workers captured by CSPAN.

“Johnny is going to be the president of the United States and he’s going to keep the traditions … and the standards high,” she told the crowd, receiving applause. “All we want is a world where we can raise our children, have a chance at prosperity and happiness, and we can vote any way we want to,” she continued before ending on a sweet note. “I can’t thank you enough … I wish I could kiss each one of you on the cheek. If I get a chance, I will.”

Image zoom Paul Sancya/AP/REX/Shutterstock

PEOPLE also spent time on with Roberta on Sen. McCain’s campaign bus in 2007. At one point, Roberta, then 95, teased her son, “I want to correct you when you start telling all those big lies.”

When the conversation turned to the “Straight Talk Express” campaign bus itself — “This is wonderful! Can you imagine me comfortable on a bus?” Roberta said — Sen. McCain asked his mother to regale the group with a story about a driving mishap in Arizona.

“It’s so dumb!” she began. “I was driving across the continent [in 2003] and had 300 miles to Los Angeles. I thought, well, I can make it tonight. So I put the gas on. I got a ticket for driving 112 miles per hour, signed my name and went on my way.”

When Meghan, then 23, praised her for the tale, Roberta responded, “Honey, I shoot my mouth off like a neophyte!”

Roberta spoke earnestly about her son, too, during the interview. “I think civilization depends on this election,” she told PEOPLE. “Johnny should have been dead 10 times already. Not just when he was a POW in Vietnam. He had so many near-misses [as a naval aviator]. He was saved for some reason.”

Image zoom Roberta McCain in 1971 BM/AP/REX/Shutterstock

Sen. McCain learned about his diagnoses with brain cancer after undergoing a surgery to remove a blood clot above his eye last summer.

The 2008 Republican presidential nominee’s office and the Mayo Clinic in Phoenix, Arizona, released a statement about the diagnosis, saying, “Subsequent tissue pathology revealed that a primary brain tumor known as a glioblastoma was associated with a blood clot. Scanning done since the procedure (a minimally invasive craniotomy with an eyebrow incision) shows that the tissue of concern was completely resected by imaging criteria.”

Previously, Sen. McCain had survived three bouts with melanoma, an aggressive skin cancer that can spread to the brain and cause bleeding. He was diagnosed with invasive melanoma in 2000, and has been regularly screened by his doctors. Two other malignant melanomas had also been removed: on his left shoulder in 1993 and his left nasal wall in 2002. All were declared Stage 0.

Image zoom John McCain Paul Morigi/WireImage

In December, Sen. McCain was hospitalized to treat side effects related to his cancer therapy. Then in April, Sen. McCain underwent surgery and was hospitalized at Arizona’s Mayo Clinic for an intestinal infection.

The six-term Arizona Republican senator, who has served Arizona in Congress since 1982, has since called his prognosis “very poor.” But he’s remained strong, something daughter Meghan — currently a cohost on The View — praised back in June.

“He is not scared, but I’m scared every day,” she told PEOPLE. “He is very courageous and incredibly physically resilient.”

Image zoom Meghan McCain, John McCain and Cindy McCain Sierra Blanco Photography

Sen. McCain’s health battle did not at first stop his political work in Washington, D.C. — where he serves as the chairman of the Senate Committee on Armed Services, a member of the Senate Committee on Indian Affairs and a member of the Senate Committee on Homeland Security and Governmental Affairs.

He famously refused to support the Graham-Cassidy bill to repeal the Affordable Care Act in September, which drew sharp criticism from President Donald Trump as others hailed him a hero.