The death of Steve Jobs at age 56 offers a stark reminder of how difficult cancers of the pancreas can be to detect and treat.

Though few details about Jobs’s illness and treatment have been made public, he announced in 2004 that he had a rare form of cancer, known as an islet cell neuroendocrine tumor, on his pancreas. Unlike the much more common forms of pancreatic cancer, this kind often can be successfully treated through surgery.

According to the American Cancer Society (ACS), one of the reasons this form of cancer tends to be more survivable is that as the tumor grows it impedes the nearby bile duct, causing jaundice. Jaundice — a yellowing of the skin — is one of the few recognizable symptoms of pancreatic cancer, and its appearance may lead to early detection of the tumor.

More common types of pancreatic cancer cause no noticeable symptoms until it’s too late to treat the disease. According to the ACS, the five-year survival rate for those pancreatic cancers is less than 4 percent.

In the United States, an estimated 44,030 people will have pancreatic cancer diagnosed in 2011; 37,660 of them will die from the disease, according to the National Cancer Institute. No screening tests for pancreatic cancer currently exist.

Jobs reportedly delayed having the tumor removed surgically for nine months so he could instead first try a special diet.

It is not clear what kind of surgery Jobs had. Tumors like his can be removed through a surgical procedure known as the Whipple, or pancreaticoduodenectomy, which entails removing not only of the tumor but also the head of the pancreas, parts of the stomach, small intestine and lymph nodes near the pancreas, according to the ACS.

Neuroendocrine tumors tend to secrete hormones that can cause complications for patients. After appearing gaunt at several public events, in 2009 Jobs announced he had been experiencing “a hormone imbalance that has been ‘robbing’ me of the proteins my body needs to be healthy.” He added, however, that the “remedy for this nutritional problem is relatively simple and straightforward, and I’ve already begun treatment.” In April 2009, he announced he had undergone a liver transplant in Memphis and his prognosis was “excellent.”

But in August Jobs resigned from Apple, saying he could “no longer meet my duties and expectations” as the company’s chief executive officer. He did not provide any details about his health. No further details were released when his death was announced Wednesday.