The large bowel session focused on functional bowel complaints, colorectal cancer risk assessment, the management of serrated polyps, and finally, the spectrum of GI side effects resulting from checkpoint inhibitor therapy.
Dr. David S. Weinberg
William Chey, MD, led with a review of novel topics in irritable bowel syndrome (IBS). He emphasized the growing influence of the microbiome considerations on current thinking about IBS, in addition to the more traditional concerns regarding altered motility, visceral perception, and brain-gut interaction. He presented data demonstrating the benefit of low-FODMAP and other diets, as well as the role of antibiotic therapy in selected patients. He also reviewed early data on fecal transplants for treating IBS.
Darren Brenner, MD, reviewed current guidelines for the management of chronic constipation. He emphasized the importance of early diagnostic testing for evacuation disorders as a possible explanation for chronic constipation (for example, anorectal manometry, balloon expulsion testing). He also suggested that earlier treatment with prescription-based agents may be warranted after failure of fiber or polyethylene glycol (PEG)–based laxatives. Finally, he discussed treatment options for constipation either induced or worsened by opioid exposure.
The role of serrated polyps in colorectal carcinogenesis has been increasingly recognized. Seth Crockett, MD, reviewed the optimal means for endoscopic recognition and removal of these lesions. Colonoscopy remains the gold standard to detect serrated polyps because stool tests (blood- and DNA-based) and computed tomography colonography typically have low sensitivities to detect these lesions.
Sapna Syngal, MD, discussed the growing role of gene panel testing for patients who have colorectal cancer (CRC) or who are at elevated risk. In most settings, all newly identified CRCs are tested for microsatellite instability – a characteristic of hereditary nonpolyposis colorectal cancer (Lynch syndrome). However, with the advent of less expensive multigene, blood-based screening tests, patients can be tested for a wide variety of genetic abnormalities, some that are typically associated with CRC and others that are not. Dr. Syngal emphasized the potential effects on immediate treatment, as well as risk stratification for other diseases, associated with broad mutation testing.
Finally, Edward Loftus, MD, reviewed the GI complications associated with checkpoint inhibitor therapy, a type of immunotherapy increasingly used for a wide range of cancers. These drugs cause colitis, hepatitis, and pancreatitis, among other adverse effects. Mild cases can typically be handled (usually as in outpatient settings) with oral steroids. However, more severe toxicities may require hospitalization and intravenous, high-dose steroids. Patients with colitis who fail steroids may require infliximab or other anti–tumor necrosis factor medications, while those with hepatitis may benefit from mycophenolate.
Dr. Weinberg is chairman of the department of medicine at Fox Chase Cancer Center, Philadelphia. He has no conflits of interest. This is a summary provided by the moderator of one of the AGA Postgraduate Courses held at DDW 2018.
