When Steve Jobs resigned as CEO of Apple last week, he said it was because he could no longer perform up to the demands of the position. Jobs is known to have been treated for pancreatic cancer, the fourth leading cause of cancer-related deaths in the United States.
Oncologists say pancreatic cancer is hard to treat because it is difficult to diagnose. The organ is embedded deep in the abdomen, symptoms only become evident in a late stage of the disease.
In 2004, Jobs announced he had undergone surgery for pancreatic cancer - a mild and rare form of the disease called an islet cell neuroendocrine tumor.
That form makes up about five percent of all of pancreatic cancers. It affects the cells that produce hormones to control blood sugar levels. The more deadly, and common, form appears in the exocrine cells of the pancreas that produce digestive enzymes.
The pancreas is a 15-centimeter-long gland tucked behind the stomach and below the liver. Pancreatic cancer can be hard to diagnose, since the early stages have no visible symptoms.
"There are no screening tests in a way mammograms are a good screening tool for breast cancer, or checking blood levels for prostate cancer," says Dr. Khaled el-Shami, a cancer specialist at George Washington University Medical Center in Washington, D.C.
Five years after cancer surgery, Jobs got a liver transplant.
"About five months ago I had a liver transplant," Jobs said at the time. "So I now have the liver of a mid-20s person.?
El-Shami says that's not surprising, because cancer in the pancreas can spread. ?Neuroendocrine tumors tend to spread from pancreas to the liver, and the liver being a vital organ, removing the cancer from the liver can result in improved survival. Liver transplant is a radical way of removing cancer in the liver.?
But el-Shami warns a transplant is not a guaranteed cure.
?It?s a balance between removing a big chunk of cancer in the liver and the risk of having a weakened immune system, which can encourage not only the original cancer to come back but also emergence of other cancers.?
Dr. Matthew Walsh is chairman of General Surgery at Cleveland Clinic.
?It tends to be a disease that does come back, does spread, does take your strength away," he says, "sort of have all the cancer-associated symptoms and people still do die from this type of cancer.?
While he has never treated Jobs and does not know the details of his case, Walsh says Jobs' operation could have had major consequences.
"In terms of nutrition - perhaps diabetes - if you don?t get all your pancreatic enzymes you will lose weight because you are not absorbing all your essential fats and so the part of what he is going through is consequences of a bad operation as well," he says. "Plus he has other issues having a liver transplant in terms of immuno-suppression that might actually affect the growth of the tumor.?
El-Shami says some types of pancreatic cancer can run in families. Smoking and alcohol use are linked to the disease. But he says there is no known cause for the majority of cases.