An international team led by Weill Cornell Medical College investigators has illuminated the precise molecular steps that enable pancreatic cancer to spread to the liver -- the event that makes the most common form of the disease lethal. By understanding this process, investigators say their discovery can lead to targeted treatments that delay metastasis, and could offer clinicians a new biomarker to test for the earliest signs of pancreatic cancer. The study, published online on May 18, 2015 in Nature Cell Biology, focuses on the role of small, spherical tumor-secreted packages, called exosomes (image), which contain tumor-derived proteins, in preparing a liver microenvironment fertile for pancreatic cancer metastasis. Nearly 49,000 people in the United States will be diagnosed with pancreatic cancer, and more than 40,000 of them will succumb to it, according to estimates from the American Cancer Society. Pancreatic cancers are among the most lethal cancers -- only six percent of patients survive five years after diagnosis, with the median survival rate being just six months. The Nature Cell Biology article is titled “Pancreatic Cancer Exosomes Initiate Pre-Metastatic Niche Formation in the Liver.” "What makes this cancer so lethal is that patients don't generally become symptomatic -- and as such aren't diagnosed -- until the cancer is very advanced and treatment options are limited," said senior author Dr. David Lyden, the Stavros S. Niarchos Professor in Pediatric Cardiology and a Professor of Pediatrics in the Department of Pediatrics at Weill Cornell Medical College. In the study, the investigators recreated the environment for pancreatic cancer using mouse models and discovered that exosomes were finding their way to the liver during the cancer's earliest stages.Login Or Register To Read Full Story