07/23/2012 06:48 pm ET Updated Jul 25, 2012

Sally Ride: Pancreatic Cancer Caused Death Of First American Woman In Space, But What Is It?

Sally Ride, the first American woman in space, died today after a 17-month battle with pancreatic cancer. She was 61 and, after several missions as an astronaut and a brief stint as a professor of Physics at the University of California San Diego, established Sally Ride Science, an organization dedicated to encouraging girls to pursue science education and careers.

Pancreatic cancer is most often associated with high profile male sufferers, such as Steve Jobs or Patrick Swayze, but it is actually the third deadliest cancer in women, according to the National Cancer Institute. That's most likely because there are no screening tests for pancreatic cancer, so it is usually diagnosed at an advanced stage -- meaning survival rates are worse than with many other cancers that are easier to catch early on, the organization reports. In fact, only 4.4 percent of pancreatic cancer patients survive longer than five years, with Ride's 17-month survival being typical.

Still, pancreatic cancer is more common and more often deadly in men. It is also more prevalent among African-Americans than it is among whites.

The pancreas is a long, flat gland behind the abdomen that aids with digestion and regulation of blood sugar levels. Not all pancreatic cancer types behave the same way. While it's currently not known what type of the cancer Ride had, specialists describe the major division in tumors: more than 95 percent of pancreatic tumors begin in the pancreas' exocrine cells, which help with digestion. The remaining 5 percent of pancreatic tumors begin in the neuroendocrine cells, which help to regulate blood sugar through insulin and glucagon. Both are extremely deadly, though neuroendocrine cancers (such as the one Steve Jobs suffered from) are slower growing, and often result in longer survival times.

As Amanda L. Chan reported at the time of Jobs' passing: "Treatments include surgery, hormone therapy, radiation or chemotherapy, MIBG radiolabeled therapy (a nuclear medicine technique) or other more early-stage approaches."