John Cazale's Death Explained: His Illness & How Old He Was When He Died

Movie fans are probably most familiar with John Cazale for his role as Fredo Corleone, the weak-willed, ultimately traitorous son of Don Vito (Marlon Brando) and older brother of Michael (Al Pacino) in "The Godfather" and "The Godfather Part II." But unlike most of the main cast of the two films, who continued to thrive on the big screen in the decades that followed, Cazale appeared in only two more movies after the latter project. That's because he died of lung cancer on March 12, 1978, at the young age of 42.

Known as a heavy smoker, Cazale was diagnosed with terminal lung cancer in May 1977 after he had started to miss theater performances. Both he and his then-girlfriend, screen icon Meryl Streep, tried to keep the diagnosis under wraps as much as possible, though it would soon be obvious to Cazale's friends and loved ones that something wasn't right with "The Godfather" star. But he had a strong support system backing him up; frequent co-star Pacino would accompany him to radiation treatments, while Streep would take on roles she wasn't comfortable with so she could help pay for her boyfriend's medical bills.

Despite his worsening condition, Cazale appeared in one of the best war movies of all time in "The Deer Hunter," joining an all-star cast that included Robert De Niro, Christopher Walken, and Streep herself as the film's female lead. However, there were times when it wasn't clear whether he'd be starring in the eventual Oscar-winning movie due to his illness.

While most of the standout moments in "The Deer Hunter" feature lead stars Robert De Niro and Christopher Walken (who reunited many years later in the much more light-hearted "The War with Grandpa"), John Cazale played an important supporting role as Stan, a co-worker and hunting buddy to the film's main friend group of Mike (De Niro), Nick (Walken), and Steven (John Savage). However, as director Michael Cimino related, he had to push hard for Cazale's inclusion in the Vietnam War-themed epic, as production company EMI didn't want him in the movie due to the costs associated with his terminal illness. 

"I was told that unless I got rid of John, [they] would shut down the picture," Cimino recalled, as quoted by the Telegraph. "It was awful. I spent hours on the phone, yelling and screaming and fighting." Similarly, Cazale's castmates showed their support for the actor during this trying time and lobbied for his casting. "He was sicker than we thought, but I wanted him to be in it," said De Niro, who shouldered his "Deer Hunter" co-star's insurance so that he could appear in the movie.

With his health declining, Cazale shot his scenes in "The Deer Hunter" ahead of everyone else's. Sadly, he died mere months later, with a brief but definitely noteworthy filmography that included parts in some of the greatest movies of the 1970s.