In October 1988, a year after Dravecky was traded from the San Diego Padres to the Giants, he underwent surgery to remove a cancerous tumor in his throwing arm.
As detailed in his Wikipedia biography, doctors had advised Dravecky not to pitch until the 1990 season. However, by July 1989, Dravecky was pitching in the minors. The next month, on August 10, Dravecky started against the Cincinnati Reds. He pitched 8 innings and won the game, 4-3.
It was Dravecky's next start against the Montreal Expos in the 5th inning he experienced tingling in his arm. In the 6th inning, he gave up a home run. He hit the next batter, Andres Galarraga. After Galarraga, Dravecky then pitched to Tim Raines. His humerus bone snapped.
Upon review of x-rays, it was found another malignant tumor had formed. The cancer returned. Two more surgeries would follow, and in 1991, Dravecky had his left arm and shoulder amputated. Dravecky went on to become a motivational speaker, which he still does today.
A San Francisco Giants/MLB short video on last year's anniversary can be found at Dave Dravecky's website. You can also view it here. Below is a short YouTube video summarizing his life after baseball: