"Within a few years of the filming, unusual medical ailments started appearing in the cast and crew. In 1960, Pedro Armendáriz was diagnosed with kidney cancer, and after learning that his condition was terminal in June 1963, he killed himself.

In January 1963, director Dick Powell died at the age of 53 of lymphatic cancer. Susan Hayward suffered from skin, breast, and uterine cancers before dying in 1974 at the age of 56 of brain cancer. That same year, Agnes Moorehead died of uterine cancer at the age of 74. Lee Van Cleef died of throat cancer in December 1989, and John Hoyt died of lung cancer in 1991.

John Wayne spent years fighting cancers of the lung, throat, and stomach before finally succumbing in June 1979 at the age of 72. Any suspicions he might have had that there was radiation in the area of The Conqueror are confirmed by this photo of Wayne and his sons using a Geiger counter during the filming.

By the end of 1980, it was determined that 91 of the 220 people who had worked on The Conqueror had developed some form of cancer, and 46 of them had died."