CT can replace colonoscopy in diagnosing immune-related colitis
For multiple years, scientists have been trying to resolve the challenging issues related to the diagnosis of intestinal diseases (polyps, ulcers, colitis, etc.). Immune-related colitis is one of the most common complications in cancer treatment. This condition is caused by monoclonal antibodies, which are used in some forms of cancer treatment. Colonoscopy with biopsy is the gold standard for colitis diagnosis. Nevertheless, this diagnostic technique is inherently invasive and uncomfortable for patients, and it can also lead to complications such as intestinal perforation. As of this moment, CT colonography, or as it is also called virtual colonoscopy, has become an alternative to colonoscopy in gastrointestinal diseases diagnosis.
In April 2017, data on the high diagnostic value, safety, and advantages of CT over colonoscopy with biopsy in the diagnosis of immune-related colitis was published in the journal Cancer Immunology Research. This retrospective study was conducted by a group of scientists from Dana-Farber Cancer Institute in Boston, MA. The study included 303 patients diagnosed with metastatic melanoma. These patients received ipilimumab as part of their treatment. This drug is a monoclonal antibody, which by blocking Cytotoxic T-Lymphocyte Antigen-4 (CTLA-4), allows T lymphocytes to kill cancer cells. However, the body’s healthy cells can sometimes also be attacked by the immune system. As a result, an autoimmune disease can develop, and ipilimumab-mediated colitis is one such example. Diarrhea is a frequent manifestation of its gastrointestinal symptoms, occurring in one-third of the patients during or after treatment. However, according to the researchers, moderate or severe symptoms that cause serious consequences develop in 5-8% of patients.
“Considering the life-threatening nature of ipilimumab-related colitis and favorable response to steroids in early treatment, timely and accurate diagnosis is of much importance,” noted the researchers. This is precisely why abdominal CT, taking into account its informative value, speed, and lower aggressiveness, can replace colonoscopy as a primary diagnosis technique.
This study evaluated positive and negative predictive values, sensitivity, and specificity, as well as the positive and negative likelihood ratios of CT as an alternative to the golden standard – colonoscopy with biopsy. In total, 99 (33%) patients out of 303 had diarrhea during therapy. There were 46 (15%) patients with manifestations of colitis who received corticosteroids. The patients with diarrhea were split up into two groups: 48 (48%) of them underwent colonoscopy, 46 (46%) underwent both CT and colonoscopy.
Scientists compared the CT scan data, namely fluid and air levels in intestines, condition of the intestinal walls, and mesenteric stranding with colon mucosa biopsies being decisive for colitis diagnosis. Additionally, they correlated CT results with effective use of corticosteroids in the 15% of patients who needed them to treat colitis symptoms.
In 34% of patients who underwent both CT and biopsy, CT results coincided with biopsy data and were highly predictive in 96% of patients. Negative CT results were predictive of negative biopsy results. Besides that, CT had a 92% positive predictive value for corticosteroids treatment in resolving symptoms. Nevertheless, the results are not necessarily definitive and further study is required. Yet, if CT is negative and there is still suspicion, doctors should perform a colonoscopy to accurately determine the diagnosis.
Dr. Patrick Ott, MD, PhD – one of the study authors – said, "We conclude that CT is a fast, reliable, and noninvasive mode of diagnosing colitis, whereas colonoscopy and biopsy may not be needed to establish that diagnosis,"
The BiMedis platform offers a large variety of both colonoscopes and CT scanners. Thanks to our large equipment selection, you will always be able to make the right choice, which will help you diagnose complex diseases.
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