November 22, 2016
Tumor DNA circulating in the bloodstream can indicate many types of cancer.
The spirit of collaboration and collegiality among Johns Hopkins experts working on pancreatic disease extends beyond clinical care and all the way to research. Johns Hopkins researchers are breaking new ground all the time in the fight against pancreatic disease.
Promising Possibilities: Liquid Biopsies
Detecting cancer via a blood test has long been a goal in medicine. Advances in genomic sequencing are helping physicians at Johns Hopkins close in on that goal, especially as it relates to pancreatic and a few other gastric cancers.
Since a landmark 2014 study of “liquid biopsies,” Johns Hopkins researchers and clinicians are gaining ground on this important diagnostic tool.
Two sources of valuable cancer-related information can be found circulating through a patient’s bloodstream: actual tumor cells and cell-free circulating tumor DNA, or ctDNA.
The study, led by neurosurgeon Chetan Bettegowda and co-authored by colleagues in gastroenterology, surgery and other fields, showed that many types of cancer could be detected with a blood test, as the test revealed ctDNA in bloodstreams. Bladder, colorectal, ovarian and gastroesophageal cancers were detectable via the patient’s blood 100 percent of the time, followed by pancreatic ductal cancer, at nearly 90 percent.
Other cancers were less reliably detectable through ctDNA. Thyroid cancer and glioma were detectable less than 20 percent of the time.
Study: Using Genetics and Math to Determine Which Cysts Need Surgery
Scientists at Johns Hopkins late last year published a report in the journal Gastroenterology that could help patients avoid unnecessary pancreatic surgery.
In a “look-back” analysis of data stored on patients with pancreatic cysts, the study’s authors used gene-based tests and a fixed set of clinical criteria to more accurately distinguish precancerous cysts from those less likely to do harm.
Currently, doctors test fluid collected from a needle that penetrates a cyst during a procedure called an endoscopic ultrasound-guided biopsy. The fluid is tested for proteins associated with cancerous cysts and pathologists examine samples to find atypical cells signifying cancer. But the results are accurate only about two-thirds of the time, says Anne Marie Lennon, director of the Multidisciplinary Pancreatic Cyst Program.
“We felt those prediction numbers could be much better,” says Lennon.
In the study, the scientists built on preliminary gene tests they developed in 2011 that measure the presence of pancreatic cancer-linked genetic markers in cyst fluid samples. They expanded the panel of genetic markers and tested them on cyst fluid from 130 patients who had surgery to remove cysts at The Johns Hopkins Hospital and 16 other hospitals in the United States and other countries.
In addition to using genetic-based markers, the scientists developed a mathematical model that identifies various types of pancreatic cysts and their potential for malignancy by taking into account patient characteristics such as age and symptoms, as well as appearance and location of the cysts, based on medical record information from 1,026 patients who had surgery to remove cysts at The Johns Hopkins Hospital.
“Our study shows that our expanded panel of genetic markers, combined with clinical acumen, can accurately differentiate between types of pancreatic cysts and identify cysts that are safe to watch over time and cysts that need to be removed,” says co-author Ralph Hruban, director of the pathology.
“Correctly identifying whether pancreatic cysts pose a high risk for malignancy is key to preventing an often deadly cancer, or avoiding a needless surgery for cysts not likely to be a problem,” says Bert Vogelstein, co-author and director of the Ludwig Center at the Johns Hopkins Kimmel Cancer Center.
Doorways to Discovery: Liquid Biopsy to Track Cancer
Chetan Bettegowda, M.D., Ph.D., a Johns Hopkins neurosurgeon, discusses his research on a new liquid biopsy to screen asymptomatic people to detect cancers when they are not yet clinically detectable. Watch video