Hats off to CAPS
Date: April 1, 2011
Pancreatic cancer is both quiet and deadly—it’s no surprise that the disease’s stealth goes hand-in-hand with its high mortality. “We see most pancreatic cancers when patients come in with symptoms,” says gastroenterologist Mimi Canto, “but by then, the disease is pretty much incurable.”
Yet two rays of optimism are cutting the darkness. One is that recent Hopkins studies have shown the tumors aren’t such rapid growers as we’d thought. Sometimes twenty years or more elapse from the time the earliest cell abnormalities morph into anything metastatic.
And light also shines from milestone studies that Canto began a decade ago and continues to run with colleagues. Called CAPS, for cancer of the pancreas screening, the research aims to lock in the best practices to diagnose early cancer in high risk patients.
Together, the studies raise hopes of catching the disease at a point when a surgical cure is more likely.
Canto is expert in endoscopic ultrasonography (EUS), the technique that transmits from within the organ to detect pancreatic lesions as small as 2 millimeters. So CAPS 1 and 2, a pilot and its somewhat larger follow up study, aimed to see if ultrasound imaging could become an early warning system. Canto invited at-risk, close relatives of familial pancreatic cancer patients to Hopkins for screening.
The promising work led to CAPS 3, a large, Hopkins-led multicenter study that added CT and MRI as comparison screening tools. Now, data from all the trials leaves no doubt of the importance of screening those at high risk: “43 percent of the symptom-free people we examined had at least one pancreatic lesion,” Canto says. “And of those, more than half had a number of them, often in different locations.”
How do the separate imaging techniques measure up so far? “We’ve confirmed that EUS and MRI are best for detecting small precancerous lesions within ducts,” says Canto. And smaller cystic abnormalities deeper in pancreatic tissue are best seen with EUS or MRI.
There’s more: CAPS 3 also tried out a Hopkins-developed computational method called PancPro—a way to score a person’s individual risk of pancreatic cancer and better target who needs screening. And it tested the ability of an agent to improve MRI imaging of pancreatic ducts. Results of both will appear in upcoming publications.
What has been published is a valuable offshoot of the screening. Over the studies’ 10 years, 36 people have had successful surgery at Hopkins for suspected tumors, creating resected tissue for pathologist Ralph Hruban to study
The finding: tiny cancer precursors in the large and small pancreatic ducts of these asymptomatic participants caused obstruction and chronic pancreatitis, even though usual risks like alcoholism weren’t there.
Now CAPS 4, ongoing and Hopkins-centered, has broadened screening to include patients at slightly less risk. And CAPS 5? It’s a landmark international collaboration, still in the planning stages.
In Baltimore, Canto recently presided over a mini-United Nations of experts aiming for consensus on what the study still needs to answer. “This one is a really big deal,” Canto says. “In the long run, it could shift the status of pancreatic cancer screening worldwide.”