Two newly identified subtypes of pancreatic cancer cells and of nearby normal pancreatic cells contribute to differences in patient survival, reports a study published online this week in Nature Genetics. The findings may help doctors better plan individualized treatments for patients with the most common type of pancreatic cancer.

Pancreatic ductal adenocarcinoma is a deadly disease, with a 5-year survival rate of only 4%. Normal cells surround the cancer cells and make it difficult to pinpoint the molecular changes that occur specifically in cancer cells and contribute to the development of pancreatic cancer, as tumor samples are a mixture of both normal and cancer cells. In addition, there is little known about the variation among pancreatic cancer samples at the genetic level, limiting the development of new treatments.

Jen Jen Yeh and colleagues used gene expression data from previous studies of pancreatic cancer to virtually separate the genetic signatures of tumor and normal cells. The authors further dissected the signals to show that there were two subtypes of both cancer and normal cells, each of which affected patient outcome differently. One of the tumor subtypes had a worse prognosis, with a 1-year survival rate of 44%, compared to the second subtype with a 1-year survival rate of 70%. Each subtype was associated with different gene mutations.

The authors also found that the tumor subtype with the worse outcome was molecularly similar to tumors in bladder and breast cancers, and patients with this subtype appeared to respond better to more aggressive and personalized therapies. However, future studies are needed to determine how each subtype is associated with response to specific therapies.