(CNN) -- As the technology world mourns computing visionary and Apple, Inc. co-founder Steve Jobs, it's worth taking a closer look at the disease he publicly battled.
Jobs had a rare form of pancreatic cancer called a neuroendocrine tumor. Patrick Swayze, Joan Crawford, Margaret Mead and Luciano Pavarotti all died from a more common form of pancreatic cancer, called adenocarcinoma. Supreme Court Justice Ruth Bader Ginsburg underwent surgery for pancreatic cancer in February 2009 and, 18 days later, returned to the bench.
"Right now, pancreatic cancer is getting publicity, but it's a neglected disease," said Dr. Michaela Banck, medical oncologist at the Mayo Clinic, who treats patients with neuroendocrine tumors. "It doesn't draw the same attention as colon cancer and breast cancer. Activist groups raise small amounts of money, since it's a rare disease. It's a complicated disease. We don't have enough money to make progress as fast as we'd like to."
Who gets pancreatic cancer
Pancreatic cancer is the fourth-leading cause of death from cancer in the United States, after lung, colon and breast cancer. The lifetime risk of developing it is about 1 in 71. This year, about 44,030 people will be diagnosed with pancreatic cancer, and the disease will kill about 37,660 people, according to the American Cancer Society.
About 95 percent of people with pancreatic cancer die from it, experts say. It's so lethal because during the early stages, when the tumor would be most treatable, there are usually no symptoms. It tends to be discovered at advanced stages when abdominal pain or jaundice may result. Presently, there are no general screening tools.
Rates of pancreatic cancer have dropped slightly among men and women over the past 15 to 25 years.
As people age, the risk of developing pancreatic cancer goes up. Most patients are older than 45, and nearly 90% are older than 55. The average age at diagnosis is 72.
Men have a slightly higher likelihood of developing pancreatic cancer than women, which may partly result from increased tobacco use in men. In the past, when men more commonly smoked than women, the gender gap was wider.
There is also a noted association with race: African-Americans are more likely to develop pancreatic cancer than whites. Doctors don't know why, but speculate that higher rates of men smoking and having diabetes, and women being overweight, may contribute to that association.
What are the types of pancreatic cancer?
The pancreas is an oblong organ that lies deep in the abdomen, and is an integral part of both the digestive and endocrine system. It secretes hormones to regulate the body and also digestive enzymes to break down food.
There are two types of pancreatic cancer: exocrine tumors and endocrine tumors.
Exocrine tumors are the majority of pancreatic cancers, and the most common form is called adenocarcinoma, which begin in gland cells, usually in the ducts of the pancreas. Swayze died from this kind of pancreatic cancer. These tumors tend to be more aggressive than neuroendocrine tumors, the kind that Jobs had, but if caught early enough they can be treated effectively with surgery.
Pancreatic neuroendocrine tumors constitute only 1% of all pancreatic cancers. They can be benign or malignant, but the distinction is often unclear and sometimes apparent only when the cancer has spread beyond the pancreas.
The five-year survival rate for neuroendocrine tumors can range from 50% to 80%, compared with less than 5% for adenocarcinoma.
More advanced tumors have a higher risk of recurrence, and can spread to the liver, said Dr. Steven Libutti, pancreatic cancer expert and director of the Montefiore-Einstein Center for Cancer Care in the Bronx.
Pancreatic cancer is usually controllable only through removal by surgery, and only if found before it has spread, according to the National Cancer Institute. Palliative care can help a patient's quality of life if the disease has spread.
Two new drugs approved this year may help patients with pancreatic neuroendocrine tumors. They are believed to suppress the blood supply and metabolism of the tumor cells. That's good progress since, a year ago, the standard of care was chemotherapy, Banck said.
Everolimus, marketed by Novartis as Afinitor, received U.S. Food and Drug Administration approval to treat pancreatic neuroendocrine tumors and prevents transplant rejection. Potential side effects are serious, however: lung or breathing problems, infections and renal failure, which may lead to death.
Sunitinib malate, marketed by Pfizer as Sutent, is prescribed for the treatment of pancreatic neuroendocrine tumors, as well as, kidney cancer and GIST, a rare cancer of the bowel, esophagus or stomach. As with everolimus, there are risks to consider: it can cause liver problems and death.
Given that Jobs underwent surgery to remove his tumor in 2004 and died in 2011, his seven-year survival after treatment is consistent with the average survival for these kinds of tumors, Libutti said.
If pancreatic cancers are detected early, that may increase the odds of survival, but it also depends on how aggressive the particular tumors are in a patient. If surgery leaves behind microscopic aggressive tumor cells, they can cause a recurrence of cancer.
Jobs also underwent a liver transplant in Tennessee in 2009, which is "cutting edge stuff" for when neuroendocrine tumors spread, said Dr. Maged Rizk, director of the Chronic Abdominal Pain Center at the Cleveland Clinic who specializes in gastroenterology and hepatology.
But because it's so rare, there isn't a lot of evidence to support the transplant as a cure; the procedure could extend life, but immunosuppression drugs may allow any remaining cancer to grow faster, doctors say. And a European study found that the majority of patients who underwent liver transplant for this type of tumor had recurrence of the disease.
But many pancreatic cancers are detected in later stages because when the tumor is small, it often does not produce symptoms. As they grow, adenocarcinomas can obstruct the ducts from the liver and cause severe back pain. Neuroendocrine tumors sometimes produce insulin, so a patient's first symptoms could be low glucose levels. But most tumors do not produce hormones, Libutti said.
There are two rare genetic syndromes -- multiple endocrine neoplasia type 1 (MEN1) and Von Hippel-Lindau syndrome (VHL) -- that increase the risk of pancreatic neuroendocrine tumors. Other than that, though, it's unclear whether having a family member with pancreatic cancer increases an individual's risk.
Pancreatic cancer struck former President Jimmy Carter's family hard. He lost his father and all of his siblings, brother Billy and sisters Ruth Carter Stapleton and Gloria Carter Spann.
The future of treatment
Researchers are working on better understanding the way in which pancreatic tumors grow and spread, Libutti said.
"There are a number of agents that are being looked at in clinical trials that focus on pathways that may allow pancreatic cancer to evade normal processes," Libutti said.
One is an antibody that blocks a particular protein called PD-1 on the surface of pancreatic cancer, meaning chemotherapies would be more effective because there would be an enhanced immune response against the tumor. That work is being done by the National Cancer Institute.
Libutti's lab is working on targeted nanoparticle therapies for metastatic neuroendocrine tumors. The idea is that tiny particles are coated with material that hones in on tumor cells and delivers drugs to kill them without harming healthy tissue, reducing the toxicity to the body in general. This research is still in animal models.
"We're hopeful that in the not-too-distant future, we'll be ready to move into clinical trials," he said.
Another line of research is focused on finding biomarkers of pancreatic cancer so that a simple blood or urine test could be developed. Unlike screenings for other conditions such as colon, breast and prostate cancers, there is no routine way to see whether a patient has a tumor in the pancreas.
The future of medicine to help people with pancreatic cancer will involve genetics, said Banck. This would involve matching a person's particular type of tumor using genomic information with treatment.
"What's going to make real difference in the future is the revolution of the genomic era," she said.
CNN's Madison Park and Jacque Wilson contributed to this report.