John McCain’s Heartbreaking Cancer Diagnosis

Sen. John McCain has been diagnosed with the most aggressive form of brain cancer.

McCain learned about the gut-wrenching diagnosis after undergoing surgery to remove a blood clot above his eye. In a statement, his office said, "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.”

Former Vice President Joe Biden's son Beau fought for his life after being diagnosed with glioblastoma, but lost his battle in 2015.

As for the 80-year-old's state of mind after the diagnosis, the statement revealed that “he is in good spirits as he continues to recover at home with his family in Arizona."

John took to social media for the first time since news broke about his cancer diagnosis, tweeting on Thursday morning, "I greatly appreciate the outpouring of support – unfortunately for my sparring partners in Congress, I'll be back soon, so stand-by!”

His daughter, Fox News co-host Meghan McCain, also opened up on how the news has affected their family. She tweeted, "The news of my father's illness has affected every one of us in the McCain family. My grandmother, mother, brothers, sister, and I have all endured the shock of the news, and now we live with the anxiety about what comes next.”

"It is an experience familiar to us, given my father's previous battle with cancer — and it is familiar to the countless American families whose loved ones are also stricken with the tragedy of disease and the inevitability of age. If we could ask anything of anyone now, it would be the prayers of those of you who understand this all too well. We would be so grateful for them,” she continued. “He is my strength, my example, my refuge, my confidante, my teacher, my rock, my hero — my dad.”