Roberto Canessa, one of only 16 people to survive 72 days in the Andes Mountains following a plane crash, has documented his story to be released on March 1.

Canessa was only 19 years old, a second year Medicine student and rugby player then, when his Uruguayan Air Force plane crashed into the Andes Mountains in October 1972. Of the 45 passengers including the “Old Christians” rugby team and many of their supporters, only 27 survived the initial crash.

The memoir, entitled “I Had To Survive: How a Plane Crash in the Andes Inspired My Calling to Save Lives,” chronicles Cannessa’s hellish experience during those 72 days. A powerful excerpt of the crash and its aftermath can be found here, and the book is set to be released next week.

In particular, it discusses the struggles of the survivors in contemplating about eating the bodies of dead teammates and friends. The now 63-year-old cardiologist described to The Sun the process through which the group came to terms with the idea of cannibalism. Describing the “sensation of our own bodies consuming themselves just to remain alive,” the survivors knew that they would not live long without sustenance.

While Roberto first suggested it, four victims made the decision to prepare and eat the frozen bodies. “Gradually, each of us came to our own decision in our own time,” Roberto explains. “And once we had done so, it was irreversible. It was our final goodbye to innocence. We were never the same again.”

Roberto also told People Magazine of the harrowing “life or death” mission to the bottom of the mountain where they were aided by a local shepherd. He explains that the group owes their lives to this “very humble person.”

“Now when I have the chance to save the heart of a baby that is sick and comfort a very humble person, I believe I am giving back what the shepherd gave me,” the cardiologist told PEOPLE.

The miracle survival story has already been adapted for the movie screen with the 1993 film “Alive,” but Roberto says the book holds many more lessons “learned from the mountain.” The most significant message of the book, however, is that “you shouldn’t wait for your plane to fall to enjoy and be grateful for life.”