(AP) -- Pancreatic cancer is notoriously lethal - there are almost as many deaths from it each year as there are new cases. The deaths this week of Apple founder Steve Jobs and Nobelist Ralph Steinman bring unusual attention to this less-well-known type of cancer.
Jobs lived more than seven years after being diagnosed with a neuroendocrine tumor - a less common, slower-growing and more treatable type of pancreatic cancer than the kind that killed Steinman a week ago and actor Patrick Swayze two years ago.
The Apple chief kept details of his illness behind a firewall and declared he was cured after cancer surgery in 2004. However, five years later, gaunt and having lost a lot of weight, Jobs had a liver transplant. Experts said it was likely because his cancer had returned or spread.
A liver transplant sometimes can cure the type of cancer that Jobs had. But if it comes back, "it's usually in one to two years," said Dr. Michael Pishvaian of Georgetown University's Lombardi Comprehensive Cancer Center.
In January, Jobs announced his third and final leave of absence. He resigned in August and died on Wednesday.
Part of what makes pancreatic cancer so deadly is that the pancreas is as vital as the heart. You can live with just part of a liver or a colon, or only one kidney or lung. But the pancreas is a fish-shaped organ that makes digestive enzymes and insulin and other hormones that enable the body to make energy from food.
In the United States, pancreatic cancer is the fourth leading cause of cancer deaths. About 44,030 people will be diagnosed with it and about 37,660 people will die of it this year in the U.S., the American Cancer Society estimates.
Over the past 15 to 25 years, rates of pancreatic cancer have dropped slightly, possibly because of a decline in smoking, the cancer society says. However, cases have been rising since around 2002 and rose about 1 percent per year over the period 1998 to 2007, said the cancer society's deputy chief medical officer, Dr. Len Lichtenfeld.
Possible symptoms are fatigue, back pain, abdominal pain, unexplained weight loss, loss of appetite, jaundice and nausea, according to the Lustgarten Foundation, a private group that finances research on the disease.
This cancer often is not found until it is advanced or has spread, and overall survival is dismal: 20 percent after one year and only 4 percent after five years.
However, with a neuroendocrine tumor like the one Jobs had, "people can live a longer time; median survival is five to eight years," said Dr. Alan Venook, a pancreatic cancer specialist at the University of California, San Francisco.
The lifetime risk of developing pancreatic cancer is about 1 in 71, according to the cancer society. Men and blacks account for more cases than women and whites, possibly because of differences in smoking rates. Smokers have two to three times more risk of developing the disease. Use of smokeless tobacco also raises the risk.
Obese people, those who don't exercise much and diabetics also have more risk for pancreatic cancer. Alcohol use might play a role: Most studies haven't tied it to pancreatic cancer, but heavy drinking can lead to diabetes and liver and pancreas problems that pose a cancer risk, the cancer society says.
The best hope for a patient is that the tumor is operable. That was the case in February 2009, when U.S. Supreme Court Justice Ruth Bader Ginsburg had a small, early-stage pancreatic tumor removed at New York's Memorial Sloan-Kettering Cancer Center.
On the horizon are immune system treatments - research that Steinman, the Nobel recipient from Rockefeller University in New York, was studying in the lab and trying on his own pancreatic cancer.
The immune system has a hard time recognizing and fighting cancer because the enemy is not an invading germ but our own cells gone rogue. Treatments called therapeutic cancer vaccines are ways to modify cells to help the immune system recognize the risk.
One such vaccine by NewLink Genetics, a small biotech firm in Ames, Iowa, is in late-stage testing now for pancreatic cancer. The company website says the larger study was initiated after a mid-stage test suggested improvement in survival.
Dr. Roderich Schwarz, chief of surgical oncology at the University of Texas Southwestern Medical Center in Dallas, has enrolled a few patients in some immune therapy studies, which have not paid off in the past.
"Vaccines are coming along," and last year's approval of one for advanced prostate cancer suggests researchers may be learning to overcome some of the drawbacks of the past, he said.
"It's quite possible that vaccines will claim their territory in the treatment of these challenging tumors," Schwarz said. "It's still in the development stage rather than the proven stage."
Explore further: Pancreatic cancer declining, but among most deadly
More information: Cancer Institute: www.cancer.gov/cancertopics/types/pancreatic
Cancer Society: www.cancer.org/Cancer/PancreaticCancer/index
Survival rates: bit.ly/oAxKl5
Research and support: www.curePC.org and www.lustgarten.org
Vaccine study: www.linkp.com/products/hyperacute-pancreas.html