Tuesday, June 3, 2014
Gastrointestinal Cancers: Prevention and Early Detection Is the Best Cure
By: Brian A. Brunson, M.D., Gastroenterology Associates of North-Central Alabama, P.C.
Over the last couple of decades, the field of gastroenterology has been transformed. Much has been learned about natural history and precursors of gastrointestinal cancers, particularly those of the esophagus, pancreas and colorectum. In that same time period, endoscopic technology has advanced at a rapid pace, and now a majority of upper endoscopy or colonoscopy procedures performed in this country utilize ultra-flexible instruments with high definition video capability. This has allowed gastroenterologists to detect even the smallest of polyps in the colon or short segments of intestinal metaplasia in the esophagus, otherwise known as Barrett’s Esophagus. Both of these are well known to be precursors to cancer. Additionally, a procedure known as endoscopic ultrasound, or EUS, has been developed and now allows significantly better imaging and evaluation of the pancreas and bile duct, including detection and evaluation of cysts in the pancreas which also can be precursors to cancer.
With this knowledge and technology, though, comes greater responsibility. We as gastroenterologists must be prudent following guidelines for screening and surveillance based on scientific data and expert recommendations. Otherwise the cost of screening and surveillance may outweigh the benefits of cancer prevention in the population as a whole. This is especially important in the modern era of medicine with the cost of healthcare continuing to rise at a rapid pace. In some cases, though, the scientific data remains inconclusive, particularly in the case of Barrett’s Esophagus and pancreatic cysts, so these decisions are often not straightforward.
Barrett’s Esophagus, or a change in the lining of the esophagus which can lead to esophageal cancer, can be detected in up to 5-10% of patients with chronic acid reflux symptoms (such as heartburn or regurgitation), but also can be detected in some patients with no significant history of acid reflux. The first issue that we face is who to screen for Barrett’s? Multiple studies have suggested that the risk is highest in males over the age of 55 who are overweight or obese, so all those patients with reflux symptoms probably should be screened. It is not clear, though, if we should screen patients with acid reflux who don’t meet those criteria, although this is still routinely done. Once Barrett’s Esophagus is confirmed by a pathologist, the gastroenterologist is then faced with the decision on how often to repeat the endoscopy to assess for progression towards cancer, known as dysplasia. We know that patients with confirmed dysplasia are at risk for cancer, and need either frequent surveillance or specialized treatment to eradicate the Barrett’s. In Barrett’s without dysplasia, though, it is still not clear if repeat endoscopy every 2-3 years truly allows us to prevent cancer or detect it at an early enough stage to improve survival. This is particularly true of segments of Barrett’s that measure less than 3 centimeters in length. At this time, it is likely most cost-effective to screen those patients with acid reflux symptoms who meet one or more of the high risk criteria (males, over age 55, overweight or obese), and then determine intervals for repeat endoscopy based upon the presence or absence of dysplasia on biopsies and length of the segment of Barrett’s. We await more solid scientific data which will hopefully clarify these guidelines.
Similar issues exist for pancreatic cysts, which are detected more frequently in this era due to the high utilization of CT scans. The cysts are oftentimes an “incidental” finding, but we know that some cysts can lead to pancreatic cancer. Endoscopic ultrasound can often detect findings in the cyst which would identify them as higher risk, so it is quite often utilized for this purpose. EUS also allows the use of a thin biopsy needle to aspirate cyst fluid, which can be sent for tumor markers and molecular studies to further aid in identifying which cysts are higher risk for transforming to cancer. Unfortunately, the markers are oftentimes not consistently reliable. Additionally, the recommendations for timing of follow-up exams are typically based upon “expert recommendations” and not scientifically based in cases of low to moderate risk cysts. Hopefully the science in this field will continue to advance, with development of better markers to help determine exactly which patients are at highest risk and therefore need the closest surveillance.
Prevention of colorectal cancer by detection and removal of colon polyps during colonoscopy, on the other hand, is a modern day public health success story, and is now based on solid scientific data as noted in recent studies published in the New England Journal of Medicine. For colonoscopy to remain as a cost-effective tool in cancer prevention, though, it must be utilized properly by following guidelines guided by scientific data. This includes screening all people at age 50 or at age 40 or earlier if there is a family history of colon cancer. This also includes adhering to guidelines for repeat screening exams only every 10 years in patients without polyps, or sooner if pre-cancerous polyps are found and removed. Additionally, the exam must be “high-quality,” as determined by excellent cleansing of the colon prior to the procedure and adequate time spent looking for polyps.
As a practicing gastroenterologist, I am excited to be in a field with such a strong focus on cancer prevention and early detection. I also know that in the modern era of medicine, with rapidly rising costs, we must be diligent in following expert guidelines based on the best scientific data available. Otherwise we risk overutilization of procedures, which could further contribute to the risings costs of healthcare and economic burden in our country, and lead to less cost-effective screening and prevention.