Jobs would later speculate that his cancer was caused by the grueling year that he spent, starting in 1997, running both Apple and Pixar.
As he drove back and forth, he had developed kidney stones and other ailments,
and he would come home so exhausted that he could barely speak.
"That's probably when this cancer started growing, because my immune system was pretty weak at that time," he said.
There is no evidence that exhaustion or a weak immune system causes cancer.
However, his kidney problems did indirectly lead to the detection of his cancer.
In October 2003 he happened to run into the urologist who had treated him,
and she asked him to get a CAT scan of his kidneys and ureter.
It had been five years since his last scan.
The new scan revealed nothing wrong with his kidneys,
but it did show a shadow on his pancreas, so she asked him to schedule a pancreatic study. He didn't.
As usual, he was good at willfully ignoring inputs that he did not want to process. But she persisted.
"Steve, this is really important," she said a few days later. "You need to do this."