Maryam Alimirah, MD1, Sandra Naffouj, MD2, Firas Askar, BS1, Omar Sadiq, MD1, Raxitkumar Jinjuvadia, MD1, Yousuf Siddiqui, MD1
1Henry Ford Hospital, Detroit, MI; 2Henry Ford Health System, Detroit, MI
Introduction: Colorectal cancer (CRC) remains one of the leading causes of death in the United States, however only 60% of the eligible screening population is up-to date on screening. The suboptimal rate of participation in CRC screening has paved the way for less invasive screening modalities such as the multitarget stool DNA test, which is reportedly 92.3% sensitive and 89.8% specific at identifying cancerous lesions in an adult population at average risk for CRC. Anecdotal reports have brought the specificity of this test into question. We conducted a retrospective study at our tertiary care center to assess the utility of multitarget stool DNA testing in diagnosing cancerous and pre-cancerous lesions.
Methods: All patients with positive Multitarget Stool DNA Testing for Colorectal-Cancer Screening between January 1st 2016 and October 30th 2018 were reviewed. A total of 589 charts were selected for analysis of demographics, anti-platelet/anticoagulation use, and endoscopic findings. All patients with subsequent surveillance colonoscopies were included. Advanced adenomas were defined as tubular or serrated adenomas with size greater than 1 cm or tubulovillous adenomas of any size. Statistical analysis was performed using R 3.6.0.
Results: A total of 589 patients had positive multitarget stool DNA testing, of which, 427 had undergone subsequent colonoscopies. Sample characteristics showed mean age of 68.6, 60% female, mean BMI 30.2. 58% smoking history and 16% diabetics (mean A1c of 7.4). In addition to 7 diagnosed adenocarcinomas, 221 patients were noted to have an advanced adenoma. Average size of advanced adenomas was 13.3 mm ± 11.4. Low risk lesions measured 6.82 mm ± 4.66. We found a positive predictive value (PPV) of 53.4% for an advanced adenoma or adenocarcinoma. In subgroup analysis, 46.4% of aspirin users had advanced adenomas on colonoscopy, compared to 65.1% of patients on factor Xa inhibitors. 62.1% of clopidogrel users had advanced adenomas.
Discussion: Our experience with Multitarget Stool DNA Testing varies from that demonstrated in literature. Initial multicenter studies demonstrate a specificity of 87% with sensitivity of 92% for adenocarcinoma and 69% for advanced adenomas. This translates to a PPV of 87.6% and 84% respectively. In comparison, our results demonstrated a PPV of 53.4%. Further studies are required to determine if these differences also extend into the sensitivity of the test and its utility as a screening test for colorectal cancer.
Citation: Maryam Alimirah, MD; Sandra Naffouj, MD; Firas Askar, BS; Omar Sadiq, MD; Raxitkumar Jinjuvadia, MD; Yousuf Siddiqui, MD. P1141 - POSITIVE PREDICTIVE VALUE OF MULTITARGET STOOL DNA TESTING FOR COLORECTAL CANCER SCREENING. Program No. P1141. ACG 2019 Annual Scientific Meeting Abstracts. San Antonio, Texas: American College of Gastroenterology.