Apple co-founder Steve Jobs lost his battle with pancreatic cancer on Wednesday after eight years since he was diagnosed in 2003. However, his cancer -- originating from pancreatic neuroendocrine tumors -- was rare, allowing for Jobs to live longer than expected.

The neuroendocrine tumor is usually less aggressive than the more dangerous exocrine tumor, which begins to grow on gland cells in the ducts of the pancreas. Patients with the neuroendocrine form can live longer. According to CNN, pancreatic cancer usually has a five-year survival rate. The rate for neuroendocrine tumors can range from 50 to 80 percent compared to less than five percent for exocrine tumors.

What is it?

Pancreatic cancer attacks two types of glands contained in the pancreas: the exocrine glands that produce enzymes that break down fats and proteins, and endocrine glands that make hormones like insulin that regulate sugar in the blood. Jobs died of tumors in the endocrine glands, which are among the rarer forms of pancreatic cancer.

Symptoms 

According to the Los Angeles Times, neuroendocrine tumors can grow slowly; ones that are functional can secrete hormones and cause symptoms such as stomach ulcers, high blood sugar or skin rashes. Nonfunctioning tumors can grow without being noticed, and they don't produce hormones or symptoms.

Nevertheless, says Yahoo! Health, the symptoms in the early stages are vague and could be related to many other conditions. Typically, symptoms include a loss of appetite, back and abdominal pain, chronic fatigue and jaundice. During his public appearances before he retired as Apple's CEO in August, many noticed Jobs had lost a significant amount of weight, probably partly tied to a loss of appetite.

Treatment

There's a propensity for the neuroendocrine cancer to spread from the pancreas to the liver, according to said Dr. Jack Jacoub, a medical oncologist at MemorialCare Cancer Institute at Orange Coast Memorial Medical Center in Fountain Valley, California. That's why many local treatments focus on attacking cancer cells in the liver, including destroying them with heat or surgically removing them. And, that's why Jobs underwent a liver transplant in 2009.

Jobs is just one of the many famous who have also died from the rare neuroendocrine pancreatic cancer. View the slideshow to see some other notable people who have died from the more common disease: