Steve Jobs Dies at 56 After Long Battle With Pancreatic Cancer

AP Photo/Jeff Chiu

Apple Inc. Chairman and CEO Steve Jobs speaks at an Apple event at the Yerba Buena Center for the Arts Theater in San Francisco, Wednesday, March 2, 2011.

After a very long, public battle with , , co-founder of . died Wednesday. He was 56.

"We are deeply saddened to announce that Steve Jobs passed away today," the company said in a brief statement.

"Steve's brilliance, passion and energy were the source of countless innovations that enrich and improve all of our lives. The world is immeasurably better because of Steve."

Jobs had battled cancer in 2004 and underwent a liver transplant in 2009 after taking a leave of absence for unspecified health problems.

He reportedly avoided cancer treatment early on in favor of altering his diet, but eventually had the tumor – which he said was a rare form called an islet cell neuroendocrine tumor – successfully removed.

About 85 to 90 percent of people who have liver transplants will be alive one year later, and about 75 to 85 percent of people will survive at least five years after a transplant, the United Network for Organ Sharing (UNOS) said on its website.

Patients who receive liver transplants must take immunosuppressant drugs for the rest of their lives to limit their risk for rejection.

But while these drugs serve their purpose, a compromised immune system can leave patients vulnerable to other diseases.

Jobs took another leave of absence in January -- his third since his health problems began -- before resigning as CEO six weeks ago. Jobs became Apple's chairman and handed the CEO job over to his hand-picked successor, .

Most pancreatic cancer cases are asymptomatic, meaning patients rarely exhibit symptoms of an illness until it's too late to stop its spread.

Caught in its advanced stages, pancreatic cancer, which affects about 30,000 people a year, has a 5 percent survival rate for five years. Caught early enough and treated with surgery and chemotherapy, the five-year survival rate goes up 17 to 25 percent.

Islet cell neuroendocrine tumors are typically a less aggressive, less common form of pancreatic cancer, representing only 1.3 percent of cases. Pancreatic cancer usually proves fatal within 4 to 6 months of diagnosis, but neuroendrocrine tumors tend to have a much better survival rate.

In 2010, there were 43,140 new cases and 36,800 deaths, according to the National Cancer Institute website. Most cases aren't diagnosed until it reaches the later stages, making it the fourth leading cause of death in both men and women. Patients are typically in their mid-to-late 60s and cases are usually sporadic.

But there are risk factors including smoking, heavy drinking, and in some cases a genetic predisposition for the disease. Some sufferers of chronic pancreatitis may also be at risk.

Besides eating right and abstaining from smoking and heavy drinking, there's very little that can be done to prevent the disease.

In 2005, following the bout with cancer, Jobs delivered Stanford University's commencement speech.

"Remembering that I'll be dead soon is the most important tool I've ever encountered to help me make the big choices in life," he said. "Because almost everything -- all external expectations, all pride, all fear of embarrassment or failure -- these things just fall away in the face of death, leaving only what is truly important."

The Associated Press and FoxNews.com's Karlie Pouliot contributed to this report.