The task force conclusions are not surprising. To date, there are no good, reliable, low-risk ways to screen for cancerous tumors in the pancreas. But the report is fodder for growing discussions on how to best diagnose and treat one of the most lethal forms of cancer. Pancreatic cancer kills about 46,000 Americans a year, according to the American Cancer Society, and may soon surpass colorectal cancer as the second-leading cause of cancer death in the United States, according to some estimates. The disease is often detected at a late stage, progresses quickly, and is challenging to treat, says Chien-Wen Tseng, MD, MPH, a member of the USPSTF and a professor and associate research director in the department of family medicine and community health at the University of Hawaii John A. Burns School of Medicine in Honolulu. The five-year survival rate for all stages of pancreatic cancer combined is only 9 percent, according to the American Cancer Society. “Even when we find it at early stages, it often doesn’t result in a cure,” says Dr. Tseng. “It’s a tough cancer. But it’s a rare cancer.” RELATED: 2 Challenges and 3 Advances in Treating Pancreatic Cancer
Evaluating the Evidence for Pancreatic Cancer Screening
To review the value of screening asymptomatic people for the disease, the USPSTF looked at 13 studies. Most of the research was done on individuals who are known to be at high risk for pancreatic cancer, such as those with a family history or who know they carried gene mutations, such as a BRCA gene, that elevate risk. The task force issued a “D” recommendation, meaning experts found no evidence that screening can reduce death rates in asymptomatic people and that there is potential harm from screening. In 2004, the USPSTF also issued a “D” recommendation for pancreatic cancer screening of asymptomatic people. “When we talk about screening, we want a test that is going to be extremely accurate at finding it in the very few people who have it and not finding it in the many people who don’t have it,” Tseng says. “Aside from just finding pancreatic cancer, we need to find it early enough so we can cure or treat it.” The potential harm from screening asymptomatic people is a key part of the “D” recommendation, says Tseng. Imaging can sometimes find noncancerous lesions in the pancreas. These lesions may or may not become cancerous, while surgery to remove them can be risky. “Up to 60 percent of patients who undergo surgical resection for a precursor lesion are found to have a lesion with a low risk of progression,” wrote Anne Marie Lennon, MD, PhD, the clinical director of gastroenterology at Johns Hopkins University in Baltimore, in an editorial accompanying the recommendation paper. Most Screening Options Have Limitations The problems associated with screening asymptomatic adults are many, experts say. Imaging techinques, using ultrasound, MRI, or CT, are considered unhelpful in distinguishing harmless, noncancerous lesions from cancerous tumors. What’s more, the position of the pancreas, tucked behind the stomach, makes imaging particularly difficult. “If you can see a lesion in the pancreas on a CT scan, which is the best method we have now, it’s already a concern that it may be too late,” says Keith D. Lillemoe, MD, the chief of surgery at Massachusetts General Hospital in Boston, who was not involved in the USPSTF recommendation. “Right now, I don’t see any imaging that helps us detect these lesions in a widespread fashion, such as with mammographic screening” for breast cancer detection. Blood tests to look for DNA shed by the tumor into the bloodstream, called circulating DNA tests or liquid biopsies, are in development, he adds. But none are ready for use in the clinic. “These are not tests readily available to the general public. Most are still done in the research perspective.” RELATED: How to Eat When You Have Pancreatic Cancer
For People at High Risk: A Question Mark
The “D” recommendation was only for asymptomatic people, not people who have an increased risk of developing pancreatic cancer. Whether people who are at higher risk for pancreatic cancer should be screened is unclear, though studies are underway to determine the answer. People with a strong family history of the disease are considered at higher risk for pancreatic cancer, as are people with particular gene mutations or inherited genetic syndromes, including the BRCA 2 gene mutation, the PALB2 gene mutation, atypical multiple mole melanoma (FAMMM) syndrome, familial pancreatitis (usually caused by the PRSS1 gene mutation), Lynch syndrome (caused by mutations in the STK11 gene) and Peutz–Jeghers syndrome (caused by the STK11 gene mutation). Other factors may also increase the risk of the disease, according to the American Cancer Society, such as being overweight; some workplace exposures, such as working around dry-cleaning chemicals; African American ethnicity; having diabetes or chronic pancreatitis; a diet high in processed foods; and heavy alcohol intake. Anyone known to be at higher risk for the disease should talk to their doctor about disease prevention, says Tseng. Gradual Improvement in Strategies for a Tough to Treat Cancer Some experts express optimism about future improvements in the prevention, detection, and treatment of pancreatic cancer. Researchers are particularly interested in studying the role of precancerous lesions that are sometimes found in the pancreas, to better characterize which ones pose a true risk of turning into cancer. These lesions are sometimes found by accident in people who are undergoing imaging for other reasons, says Dr. Lillemoe, who cowrote a second editorial accompanying the USPSTF report. But more research is needed to understand which precancerous lesions need to be removed. “These asymptomatic lesions can be found in 3 to 4 percent of all abdominal imaging done in this country,” he says. “How do you determine which of these lesions to go chasing after? Surgery in the pancreas is a high-risk procedure. We don’t want to hurt patients by removing a lesion that has no risk.” For people diagnosed with the disease, surgery to remove the cancer, while challenging, is safer than it used to be, Lillemoe says. Moreover, some patients can be treated with chemotherapy and radiation before surgery to improve their chances for longer survival. Two decades ago, Lillemoe says, “For all comers with pancreatic cancer, the five-year survival rate was 3 percent. Now that number has more than doubled. We are now finding precursor lesions and have better surgical and better chemotherapy outcomes. So we have made progress.”
