A new set of genes has been identified that can indicate improved survival after surgery for patients with pancreatic cancer. The study, published in Nature Communications (2015; doi:10.1038/ncomms8686), also showed that detection of circulating tumor DNA in the blood could provide an early indication of tumor recurrence.
Using whole-exome sequencing, which looked at the DNA protein-coding regions of 24 tumors, and targeted genomic analyses of 77 other tumors, the study identified mutations in chromatin-regulating genes MLL, MLL2, MLL3, and ARID1A associated with improved survival, in 20% of patients.
In addition, using a liquid biopsy analysis, the study found that 43% of patients with pancreatic cancer had circulating tumor DNA (ctDNA) in their bloodstream at the time of diagnosis.
Very importantly, the study also found that detection of ctDNA following surgery predicts clinical relapse of the cancer and poor outcomes for patients. In addition, using a liquid biopsy detected the recurrence of cancer 6.5 months earlier than using CT imaging.
“These observations provide predictors of outcomes in patients with pancreatic cancer and have implications for detection of tumor recurrence, and perhaps someday for early detection of the cancer,” said coauthor Daniel D. Von Hoff, MD, FACP, distinguished professor and physician-in-chief of the Tranlational Genomics Research Institute (TGen), co-director of TGen’s SU2C Pancreatic Cancer Dream Team, and chief scientific officer at the Virginia G. Piper Cancer Center Clinical Trials at HonorHealth (formerly Scottsdale Healthcare).
The pancreatic cancers analyzed in the study were stage II tumors from patients who underwent potentially curative surgery. Only 15% to 20% of patients are candidates for tumor resection, because pancreatic cancer is difficult to detect and usually is not diagnosed until its late stages when surgery is no longer an option. The 5-year survival rate for those with a diagnosis of pancreatic cancer is less than 10%.
The study’s results found that a significant number of early stage pancreatic cancers could be diagnosed noninvasively using liquid biopsy blood analysis that focuses on a few specific genetic alterations.