When Apple CEO Steve Jobs put out a cryptic statement this week about his widely discussed weight loss, he practically guaranteed a new round of speculation about its cause.
He also ensured the speculation would include a fresh dose of misconceptions about what he might be suffering from.
In his statement, Jobs ascribes his weight loss to "a hormone imbalance [that] has been robbing me of the proteins my body needs to be healthy." He says "sophisticated blood tests have confirmed this diagnosis."
Medical specialists reading these tea leaves say the biggest misconception is about the particular type of pancreatic cancer Jobs had 4 1/2 years ago. It's not the usual kind that arises from the pancreas cells that churn out digestive enzymes. Those more typical cancers all too often kill rapidly.
Jobs' cancer grew from islet cells, the 2 percent of pancreas cells that make insulin and other hormones important in the conversion of food to energy and body mass. These islet cell, or neuroendocrine, tumors typically grow slowly. They can sometimes be cured with surgery of the type Jobs had in 2004.
And not uncommonly, these cancers can recur years after the first diagnosis, often in the liver.
Dr. Clay Semenkovich, chief of endocrinology, metabolism and lipid research at Washington University in St. Louis, says if he saw a patient with Jobs' history and chronic weight loss, "the first thing I'd worry about is whether this tumor had somehow metastasized."
That's because the errant tumor cells can churn out prodigious amounts of the hormones their noncancerous ancestor cells produced — hormones such as insulin, glucagon and somatostatin.
"All can be associated with weight loss, diarrhea and protein wasting," Semenkovich says.
But these metastases can pose a diagnostic problem for doctors because they're often not visible on the most sophisticated abdominal scans.
When specialists suspect an islet cell metastasis and the CT, MRI and PET scans are uninformative, they often turn to fancy blood tests called "dynamic stimulatory tests." They inject substances that stimulate abnormal hormone secretion and then watch how the patient responds.
"That could give you a hint that somebody is making inappropriate levels of hormones that are antagonizing your ability to store nutrients," Semenkovich says.
When doctors find such a situation, they need to know what hormone is being overproduced in order to treat the problem. Too much insulin will lead to weight gain, because insulin causes the body to store calories.
A tumor that's cranking out too much glucagon — a sort of anti-insulin — can cause problems with protein metabolism. It causes the breakdown of protein stores, and the amount of protein in the diet can't replace the amount being broken down. That can produce chronic weight loss.
These so-called "glucagonomas" often cause a telltale, hard-to-miss skin rash — but not always.
Treatment for this type of recurrence is fairly straightforward: injections of a synthetic hormone called octreotide. This mimics the hormone somatostatin, suppressing production of glucagon and other hormones.
If the tumor metastasis is a type that secretes somatostatin, that poses a more difficult treatment problem, says endocrinologist Michael D. Jensen of the Mayo Clinic. "I would have to call up my oncology colleagues and ask what kinds of things they have in their book of treatments to treat the primary tumor," he says.
But cancer specialists and endocrinologists stress that people with other types of metastatic islet cell tumors often do well for years — and have a good quality of life — even if the cancer cannot be cured.
If they respond to treatment, "these tumors don't tend to get massive and very injurious to health the way the standard kind of pancreatic cancers do," Jensen says.
Of course, Jobs may not have a metastatic islet cell tumor at all. But if his diagnosis is some other "hormonal imbalance," his statement has left experts scratching their heads.
"I was actually impressed by the obscurity of the statement," says Semenkovich, the St. Louis specialist. "It's as if it transmitted information without transmitting any information at all. But if he has a metastatic islet cell neuroendocrine tumor, he can do exceptionally well. Time will tell."