John McCain Goes on Hike with Daughter Meghan Just 3 Days After Brain Cancer Diagnosis

John McCain is not letting his brain cancer diagnosis prevent him from enjoying time with his daughter.

On Saturday, the 80-year-old politician went on a hike with his daughter Meghan McCain and their dog. “Amazing hike with Dad @SenJohnMcCain this morning,” Meghan, 32, wrote on Twitter. “Thank you all for your best wishes!”

Her message came attached to a photo of the two sitting on a bench overlooking the stunning terrain in Arizona, where John is recovering from a minimally invasive craniotomy he received at Phoenix’s Mayo Clinic on July 14 to remove a 5-cm blood clot associated with the cancer from above his left eye.

It was during that surgery when doctors first discovered the cancerous brain tumor associated with a blood clot.

The cancer, known as glioblastoma, is one of the most aggressive and highly invasive forms of cancer — and makes up about half of all malignant (cancerous) brain tumors, affecting around five people out of 100,000 per year. United States Senator Edward “Ted” Kennedy, Delaware attorney general (and son of former Vice President Joe Biden) Beau Biden also had glioblastoma.

The median survival rate is about 14 to 14.5 months (up from eight to 12 months in recent years), and with current treatment about 5% of patients make it to a survival rate of five years or more, TIME reported. Treatments include surgical resection (i.e. having as much of the brain tumor removed as possible via a roughly half-day surgical procedure), chemotherapy, and radiotherapy.

The former Republican presidential nominee said in a statement that the senator and his family are reviewing further treatment options with his Mayo Clinic care team and that his “treatment options may include a combination of chemotherapy and radiation.”

John, who has served Arizona in Congress since 1982, is a three-time survivor of 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.

RELATED VIDEO: John McCain Diagnosed with Brain Cancer

Meghan remains glued to her father’s side since his health crisis, explaining on Twitter Wednesday that she, her mother Cindy, and her siblings (Douglas, 57, Andrew, 55, Sidney, 50, John Sidney, 31, James, 29, and Bridget, 25) have “endured the shock of the news,” and are now living “with the anxiety about what comes next.”

“It won’t surprise you to learn that in all this, the one of us who is most confident and calm is my father,” she wrote. “He is the toughest person I know. The cruelest enemy could not break him. The aggressions of political life could not bend him. So he is meeting this challenge as he has every other.”

“Cancer may afflict him in many ways: But it will not make him surrender. Nothing ever has,” she added.

She ended her emotional explaining that her love for her father will never go away.

“My love for my father is boundless, and like any daughter I cannot and do not wish to be in a world without him,” she wrote. “I have faith that those days remain far away. Yet even in this moment, my fears for him are overwhelmed by one thing above all: Gratitude for our years together, and the years still to come. He is a warrior at dusk, one of the greatest Americans of our age, and the worth heir to his father’s and grandfather’s name. But to me he is something more.”

“He is my strength, my example, my refuge, my confidante, my teacher, my rock, my hero — my dad,” Meghan concluded.