Aug. 18, 2018
According to the National Cancer Institute, pancreatic cancer is the third leading cause of cancer death among men and women in the United States and accounts for more than 41,000 deaths annually. With a survival rate of less than 5 percent, pancreatic cancer is among the more deadly forms of gastrointestinal (GI) cancers, partly because the majority of these cancers are diagnosed at an advanced stage. Therefore, developing strategies for early detection of this disease is critical for improving patient outcomes.
Currently there are no screening tests for pancreatic cancer, and few studies have examined the use of abdominal imaging screening for individuals at high risk of pancreatic cancer based on family history or genetic variants. To address this, Mayo Clinic researchers performed a meta-analysis of prospective cohort studies to determine the diagnostic yield and outcomes associated with abdominal imaging screening for asymptomatic, high-risk adults.
Mayo researchers conducted a systematic review of multiple electronic databases and conference proceedings through July 2017. Through that review, they identified prospective cohort studies (with more than 20 participants) of asymptomatic adults determined to be at high risk of pancreatic cancer. That high-risk group, those with a lifetime risk of more than 5 percent, included individuals with specific genetic-associated conditions who were screened by endoscopic ultrasound (EUS), magnetic resonance imaging (MRI) or both to detect pancreatic lesions.
The list of genetic-associated conditions included:
- Familial pancreatic cancer
- Peutz-Jeghers syndrome
- Hereditary pancreatitis (HP or PRSS mutations)
- Hereditary colon cancer (Lynch syndrome or mismatch repair mutations MLH1, MSH2, MSH6 and PMS2)
- Seven specific gene mutations (BRCA1, BRCA2, PALB2, STK11, ATM and CDKN2A)
The study's primary outcome was identification of high-risk pancreatic lesions at initial screening, including high-grade pancreatic intraepithelial neoplasia, high-grade dysplasia or adenocarcinoma, and overall incidence during follow-up. Summary estimates were reported as incidence rates per 100 patient-years.
The review identified 19 studies that included 7,085 individuals at high risk of pancreatic cancer. From that group, 1,660 were evaluated by EUS, MRI or both, 59 high-risk lesions were identified (43 adenocarcinomas), and 257 patients underwent pancreatic surgery. Published in Clinical Gastroenterology and Hepatology, the meta-analysis yielded a number of interesting results:
- The overall diagnostic yield screening for high-risk pancreatic lesions was 0.74 (95 percent confidence interval [CI], 0.33-1.14), with moderate heterogeneity among studies.
- The number of patients needed to screen to identify one patient with a high-risk lesion was 135 (95 percent CI, 88-303).
- The diagnostic yield was similar for patients with different genetic features that increased risk, whether patients were screened by EUS or MRI.
"Our results show that performing EUS and MRI in high-risk individuals identifies a significant number of pancreatic lesions," says Michael B. Wallace, M.D., one of the study's primary investigators. Dr. Wallace is a gastroenterologist at Mayo Clinic's campus in Jacksonville, Florida, whose research focus includes the use of advanced imaging systems for detecting early cancers and precancerous lesions of the GI tract.
Although the findings suggest a role for pancreatic cancer screening in high-risk populations, Dr. Wallace and colleagues caution that further research is needed. "Before we can implement broad-based screening programs, additional research must confirm that screening is cost-effective and that it reduces mortality and outweighs the risks of testing and surgery. We are also hopeful that exploration and assessment of novel biomarkers and emerging chemoprevention strategies, refinement of current imaging technology, and improvement of surgical outcomes will have a positive impact."
For more information
Corral JE, et al. Diagnostic yield from screening asymptomatic individuals at high risk for pancreatic cancer: A meta-analysis of cohort studies. Clinical Gastroenterology and Hepatology. In press.