Baruh Mulat, MD1, Konstantin Boroda, MD2, Hilary Hertan, MD2
1Montefiore Medical Center, Bronx, NY; 2Montefiore Medical Center / Albert Einstein College of Medicine, Bronx, NY
Introduction: Colorectal cancer (CRC) is the third most common cancer diagnosed in both men and women in the United States. Fortunately, early, precancerous lesions, can be caught early with proper screening, however, only approximately 60% of the US population gets screened. The multitarget stool DNA test (Cologuard™) is an alternative to colonoscopy that might help reach more patients. We present two cases of patients with positive Cologuard tests and unexpected outcomes which posed clinical challenges.
Case Description/Methods: Case 1: A 63 year-old male who declined colonoscopy in the past opted for Cologuard, which was positive. Subsequent colonoscopy revealed several polyps including one measuring 3.5 cm in the proximal transverse colon, which was thought to be cancerous, so it was only biopsied and not removed (Figure 1). Biopsy of this polyp revealed hyperplastic changes necessitating another colonoscopy. However the patient remains lost to follow up.
Case 2: A 75 year-old male, with history of stroke, ischemic heart disease, chronic constipation and no family history of CRC presented to gastroenterology clinic after he had a positive Cologuard test. Colonoscopy was performed revealing a normal colon without mass or polyps.
Discussion: The multitarget stool DNA (Cologuard™) is highly sensitive for detecting CRC at 92%. It is a convenient alternative for patients who do not want to undergo colonoscopy, however it can sometimes create clinical dilemmas as exhibited by our cases.
In our first case Cologuard™ was able to detect a large right-sided polyp, the sensitivity for such polyps is 42%. This patient was very reluctant to undergo colonoscopy in the first place. He agreed to a noninvasive test, but it has proven difficult to get him back for another colonoscopy. This illustrates the potential ethical and medicolegal dilemmas that can arise when patients with positive stool-based tests are lost to follow up. These patients may be prone to defer colonoscopy due their initial reservations about the procedure.
In our second case, the positive Cologuard™ with normal colonoscopy raises concern for a neoplasm elsewhere in the GI tract. Some gastroenterologists perform an EGD in this situation, while others do not. The reported false positive rate for Cologuard™ is 45%, however there are no guidelines for what should be done after a false-positive result. This is an area where further research is needed.
Citation: Baruh Mulat, MD; Konstantin Boroda, MD; Hilary Hertan, MD. P1151 - MULTITARGET STOOL DNA TEST (COLOGUARD™): A DOUBLE-EDGED SWORD. Program No. P1151. ACG 2019 Annual Scientific Meeting Abstracts. San Antonio, Texas: American College of Gastroenterology.