Like most movie stars, John Wayne had some huge hits but also big turkeys over his Hollywood career.

The Conqueror, in which Duke played Genghis Khan after Marlon Brando backed out, may have made a profit at the box office but is now ranked as one of the worst films ever made.

Duke is widely believed to have been terribly miscast, even at the time, with The New Times calling the 1956 epic “an Oriental Western” with a script featuring “few unintentional laughs.”

Yet what’s even worse is what happened after the production, which created huge controversy and a question over who was to blame.

The Howard Hughes-produced movie was partly shot in Utah while the US government were conducting atmospheric nuclear testing one state over. In 1953 alone, 11 above-ground nuclear weapons tests had taken place at the site as part of Operation Upshot-Knothole at the Nevada National Security Site. Parts of The Conqueror were shot in the Escalante Desert near St George, Utah, which is 137 miles downwind from this location. The cast and crew of the Hollywood production spent many strenuous weeks here, and the filmmakers knew about the nuclear tests, but allegedly, the government had assured them that there was no risk to public health.

Tragically, within 25 years of The Conqueror’s filming, 91 out of the 220 working on the movie developed cancer, 46 of whom died from it. In 1980, Professor of Biology at the University of Utah, Dr Robert Pendelton, stated: “With these numbers, this case could qualify as an epidemic. The connection between fallout radiation and cancer in individual cases has been practically impossible to prove conclusively. But in a group this size, you'd expect only 30-some cancers to develop. With 91 cancer cases, I think the tie-in to their exposure on the set of The Conqueror would hold up in a court of law.”

It has been pointed out since that the number of cancer cases among the cast and crew was in line with the average adults in US. Many of this generation were heavy smokers, with six-packs-a-day Wayne having had a lung removed in 1964 before he died of stomach cancer in 1979. Yet then there were also those among them like Moorehead, who was a non-smoking teetotaler. Whatever the case, Hughes reportedly felt guilty about The Conqueror’s production taking place at a hazardous site and ended up buying every print of the flop for $12 million, watching it endlessly in his later years alongside Ice Station Zebra. That was until Universal Pictures purchased the movie from his estate in 1979, three years after his death.