S4105 Colonoscopy Surveillance Remains the Lynchpin in Management of Lynch Syndrome

Introduction: Lynch Syndrome (LS), also known as hereditary nonpolyposis colorectal cancer, is the most common inherited form of colon cancer. LS is due to an autosomal dominant mutation in mismatch repair genes, which causes increased microsatellite instability leading to increased risk for colonic and noncolonic tumors. Colonoscopy plays a pivotal role in preventing, diagnosing, and treating colon cancer. This case report underscores the importance of adhering to strict colorectal cancer (CRC) surveillance in patients with LS, even with multiple reassuring colonoscopies. Case Description/Methods: A 53-year-old man with a history of LS (MSH2) mutation, ADHD, MDD, and alcohol use disorder presented for routine biennial colonoscopy surveillance. Colonoscopy 3 years ago was unremarkable, and colonoscopies from 5 and 6 years prior revealed multiple flat and sessile polyps >1 cm, which were found to be noncancerous. At the time of his surveillance colonoscopy, for which he was 18 months overdue, the patient was asymptomatic, denying changes in bowel habits, bleeding, fever, weight loss, or night sweats. During the procedure, a 1 cm bi-lobed polyp was identified in the fold of the sigmoid colon at 35 cm. Polypectomy was performed with good post-resection margins. Pathology later revealed poorly differentiated adenocarcinoma, at least intramucosal, arising from background of tubular adenoma. One month after diagnosis, the patient underwent laparoscopic total colectomy with ileorectal anastomosis, partial omentectomy, and flexible sigmoidoscopy. Computed tomography scan 4 months after surgery revealed no evidence of cancer recurrence. Discussion: In patients diagnosed with Lynch Syndrome, CRC surveillance is recommended every 1 to 2 years beginning at ages 20-25 or 2 to 5 years prior to diagnosis of CRC in a family member. Our patient with LS who missed his surveillance colonoscopy by 18 months was ultimately diagnosed with CRC and required total colectomy thereafter. In patients with LS who undergo colectomy, surveillance colonoscopies are recommended every 1 to 2 years. This case highlights the importance of maintaining strict CRC surveillance intervals for early detection of CRC in patients with Lynch syndrome.