Steve Jobs and new Nobelist Ralph Steinman both died of pancreatic cancer, a killer that’s hard to spot until it’s very far advanced. But fundamental differences in their diseases made Steinman’s survival more miraculous than Jobs’. Katherine Harmon at Scientific American has a great explanation of this, starting with the fact that the pancreas is made up of two different kinds of cells:

The pancreas itself is essentially two different organs, which means two distinct kinds of tissue—and two very different types of cancer, points out [Leonard Saltz, acting chief of the gastrointestinal oncology service at Memorial Sloan-Kettering Cancer Center]. The most common kind of pancreatic cancer[s] [the kind Steinman had] originate in what is known as the exocrine portion of the pancreas. This is the main mass of the organ, which makes digestive enzymes that get shuttled to the gastrointestinal tract via specialized ducts.

“Scattered in that larger organ are thousands of tiny islands,” Satlz explains. “These are islands of endocrine tissue,” which makes hormones that are secreted into the blood. It was a cancer of these islet cells that Jobs had.

For people with Jobs’ cancer, which is quite rare, survival is measured in years. For those with Steinman’s cancer, it’s measured in months.

Steinman’s survival for four years after diagnosis may be due in part to his use of experimental immunotherapies, which were being developed by his colleagues and sometimes incorporated Steinman’s own discoveries. Jobs’ liver transplant to replace an organ riddled with metastases, on the other hand, may or may not have helped him, says Saltz—having to take immunosuppressants to prevent rejection of the new organ weakens the immune system’s abilities to fight off the cancer.

Read more at Scientific American.

Images courtesy of mattbuchanan / flickr and Rockefeller University