The official cause of death for actor Steve McQueen was a post-operative heart attack. McQueen had had surgery to remove a large tumor caused by mesothelioma cancer. His doctors believed that his weakened condition from the cancer was a significant factor in his death.
After doctors in Los Angeles diagnosed his condition as terminal, McQueen began using a clinic in Mexico for unorthodox treatments not available in the United States, including Laetrile, intramuscular injections of animal cells, megavitamins, fasting, and coffee enemas. The Tijuana, Mexico clinic where he received treatment was operated by William D. Kelly, a Texas orthodontist banned from practicing medicine in the United States.