All those vague statements about his health that Steve Jobs put out in the last few years caused endless speculation, as the world tried to read into what could really be going on.

But now, with the biography "Steve Jobs" with Walter Isaacson, we know that behind many of those optimistic statements was a cancer that was spreading from pancreas to liver, and finally to bones and elsewhere in the body. One of the biggest surprises is that while he received state of the art medical care, he went against doctors' orders many times.

When his pancreatic neuroendocrine tumor was first discovered in October 2003, doctors said he was lucky that it had been detected so early, and it could be removed before definitely spreading. But, in Jobs' own words, "I really didn't want them to open up my body, so I tried to see if a few other things would work." Those "other things" included a strict vegan diet, acupuncture, herbal remedies, and other alternative techniques - even consulting a psychic.

His family pleaded with him, but it wasn't until June 2004, when a CAT scan revealed that the tumor had grown and perhaps spread, that he had to realize he couldn't successfully will his own cancer treatment.

The surgery in July 2004 involved a modified Whipple procedure, removing part of the pancreas. But it wasn't a cure: Doctors found cancer spread to three spots on his liver during the operation. It's impossible to know whether having the surgery sooner would have removed the cancer before it had spread. Yet Jobs told everyone he had been "cured." In his famous 2005 Stanford Commencement speech, a rare moment of being forthcoming about his cancer to the public, he said "I had the surgery and I'm fine now."

Jobs also went against doctors' orders with his eating habits.

Since he was a teenager, Jobs had practiced strange routines involving fasting, and would go on obsessive diets.

That's a problem because, the stomach needs enzymes to digest food and absorb nutrients, making it harder for patients who've had pancreas surgery to get enough protein. The standard of care is to have frequent meals and a diet with a variety of proteins from meats, fish and milk. But, as Isaacson points out, "Jobs had never done this, and he never would."

Flash forward to 2008, when Jobs and his doctors knew the cancer was spreading. Besides being in pain, Jobs was losing a lot of weight. This was partly a result of the partial Whipple procedure, partly because his appetite was reduced because of cancer and morphine, and also because he insisted on the same restrictive diets and fasts he'd practiced since his teenage years. Sometimes he would spend weeks only eating something like apples, or a carrot salad with lemon, and then abruptly denounce that food.

Isaacson writes:

Beginning in early 2008 Jobs' eating disorders got worse. On some nights he would stare at the floor and ignore all of the dishes set out on the long kitchen table. When others were halfway through their meal, he would abruptly get up and leave, saying nothing. It was stressful for his family. They watched him lose forty pounds during the spring of 2008.

In a public statement he attributed his weight loss to "a hormone imbalance that has been robbing me of the proteins my body needs to be healthy. Sophisticated blood tests have confirmed this diagnosis. The remedy for this nutritional problem is relatively simple."

We all had speculations, but what that actually meant was: Jobs had a hormone imbalance because his cancer had spread to his liver.

He underwent a liver transplant in 2009, when his health was declining rapidly. It was successful, but doctors found that there were tumors throughout the organ, meaning the cancer had probably spread elsewhere. They also found spots on the thin membrane surrounding internal organs.

Jobs again went against doctors when he insisted that they not pump out his stomach when they needed to perform a routine procedure. That led to pneumonia, and he might have died. But he survived, and didn't lose his stubbornness, even while deeply sedated. He thought the oxygen monitor on his finger was "ugly and too complex," and offered ideas for making the design simpler.

His health and spirits appeared to improve after the transplant, but in November 2010 he experienced another downturn. He was a mere 115 pounds at Christmas. Doctors saw evidence of new tumors. "Every inch of his body felt like it had been punched, he told friends," Isaacson writes.

And his dietary finickiness continued. The family had a part-time cook who made him a variety of healthy options, but he would refuse them after merely touching one or two to his tongue. Cancer curbs appetite, but Isaacson suggests Jobs had a deeper complication from his psychological attitude toward food. He took a third medical leave in January 2011.

Jobs was among the first 20 people in the world to have a complete sequencing of all of the genes of his cancer tumor, and of his normal DNA. In this way, his medical team could choose specific drugs targeted at the molecular pathways that were promoting the abnormal growth of cancer cells. "I'm either going to be one of the first to be able to outrun a cancer like this, or I'm going to be one of the last to die from it," Jobs told Isaacson.

In July 2011, however, doctors had trouble pushing back against the cancer even with targeted drugs. Jobs had stopped going to work; he was in pain, couldn't eat most solid food, and passed many days watching TV.

When Jobs announced his resignation as Apple's CEO at the board meeting on August 24, the cancer had spread to his bones and other body parts.

"I've had a very lucky career, a very lucky life," he told Isaacson. "I've done all that I can do."