Pancreatic cancer experts say they are puzzled by what is ailing Apple Chief Executive Steve Jobs, because it is not clear how serious his health problems are or how directly they relate to his bout with cancer.
Last week, Jobs said he had an easily treatable "hormonal imbalance" that was robbing his body of the proteins it needs. Then, on Wednesday, the 53-year-old CEO said his problems were "more complex" than originally thought, and he would take a medical leave of absence for six months.
Doctors who have not treated Jobs say they can only speculate without hard information, but they said the tumor he was treated for in 2004 could have spread to another organ or resurfaced in the pancreas, requiring surgery or other treatment.
Jobs could also be coping with side effects of that surgery that can be treated easily, they said.
In 2004, Jobs was treated for a rare type of pancreatic cancer called an islet-cell, or neuroendocrine, tumor. Such tumors can be benign or malignant, but they usually grow slowly and are far less deadly than most pancreatic tumors.
The American Cancer Society estimates that 37,680 Americans get pancreatic cancer each year, but few get islet-cell tumors of the kind Jobs had. The tumors are easily removed surgically but recur in roughly half of patients, said Dr. Roderich Schwarz, a cancer surgeon at the University of Texas Southwestern Medical Center in Dallas.
Dr. Clay Semenkovich, an endocrinologist at Washington University in St. Louis, said in a telephone interview, "(Jobs) may have a new mass that's substantially altering his physiology and causing him to lose weight."
The pancreas--a spongy organ the size of a large banana--produces enzymes used in digestion.
Islet-cell tumors can cause over-secretion of hormones including insulin into the bloodstream, wreaking havoc on digestion and leading to drastic weight loss.
Semenkovich said that could explain Jobs' "hormonal imbalance," but added that the limited information made it hard to say for sure.
Apple's cryptic missives on Jobs' health have not deterred speculation--sparked by his gaunt appearance at an Apple event in June 2008--that his cancer has returned.
But his drastic weight loss could have other, less ominous explanations, doctors said.
Jobs' surgery in 2004 is likely to have been the so-called Whipple procedure--an extensive and complicated operation that involves several organs besides the pancreas, doctors agree.
Weight loss is a common side effect, since a partial pancreas may not be able to effectively aid in the digestion of proteins, carbohydrates and fats.
"If an operation removes 30 to 50 percent of the pancreas, you're missing cell mass that produces juices that aid digestion. It could lead to weight loss and fatigue," Schwarz said in an interview at an American Society of Clinical Oncology conference on gastrointestinal cancers in San Francisco.
"Simple and Straightforward"?
Jobs may also have insulin deficiency, which would result in diabetes, doctors said. They added that treatments for these side effects are indeed "simple and straightforward," as Jobs has said.
Schwarz said patients who lack digestive enzymes can take enzyme capsules to aid digestion, and they are effective fairly quickly.
That would not explain why Jobs would need six months of medical leave.
Joseph Kim, a cancer specialist and surgeon at the City of Hope medical center near Los Angeles, said patients whose cancers recur in nearby organs, usually the liver, can be treated using less-invasive procedures than surgery. Cancers can be cut out or burned, and the recovery takes only a few days, he said.
In Jobs' case, "we're probably talking about something more complicated, like surgery," that would take longer, Kim said. Surgery on patients with recurrent islet-cell tumors can be "extremely difficult, if not risky," he added.
Semenkovich said Jobs may need new surgery, and that six months is a reasonable time for preparation, surgery and recovery, given his weight loss. "Surgery in somebody who has lost a lot of weight is a risk," and recovery could take longer, he said.