Colon Cancer in a Young Adult: Thereʼs Muir to Know

Abstract

Colon cancer is the third most common cancer in men and in women and the second leading cause of cancer death in the United States. While up to 90% of these cancers are diagnosed in people over age 50, the remaining 10% are diagnosed in younger patients and can be related to cancer syndromes (such as Lynch), which carry increased risk of extra-colonic cancers. Here we present a patient with cutaneous sebaceous adenomas and adenocarcinoma of the colon who was found to have adenocarcinoma of the small bowel. This constellation of tumors led to the diagnosis of Muir-Torre syndrome. Our patient is a 56 year-old Caucasian man who was diagnosed with multiple cutaneous sebaceous adenomas beginning at age 27. At age 30, he was diagnosed with adenocarcinoma of the transverse colon and underwent partial colectomy. One year later, he was found to have adenocarcinoma at the splenic flexure with subsequent subtotal colectomy. He underwent colonoscopy every 6 months thereafter and EGD every 2-3 years. This year, he presented with fatigue and was found to have iron deficiency anemia (Hgb 6g/dL, ferritin 5). After unrevealing, EGD and colonoscopy, subsequent capsule endoscopy followed demonstrated a large circumferential, ulcerated mass in the proximal jejunum. Push enteroscopy with biopsy revealed adenocarcinoma of small bowel. The patient underwent small bowel resection. He was referred for genetic testing which showed a genetic variant of uncertain clinical significance in the MSH6 gene (gene associated with Muir-Torre). Muir-Torre syndrome is a variant of Lynch that includes a predisposition to certain skin tumors. Based on diagnostic criteria published by Torre in 1995, a diagnosis of Muir-Torre should be suspected in patients with at least one cutaneous malignancy and at least one visceral malignancy (colon, stomach, small bowel, among others). Gastroenterologists must think about Muir Torre in the appropriate patient population and help coordinate appropriate cancer screening. The National Comprehensive Cancer Network (NCCN) 2013 screening guidelines include colonoscopy, EGD, and other screening tests are varying intervals. The NCCN does not recommend specific screening for small bowel cancer. A recently published study did not support screening for small bowel neoplasia in Lynch patients with capsule endoscopy. However, as demonstrated in this case, capsule endoscopy can be a useful tool in evaluating patients at increased risk for small bowel neoplasms. The Revised Bethesda Guidelines for testing colorectal tumors for microsatellite instability (MSI) Tumors from individuals should be tested for MSI in the following situations: 1. Colorectal cancer diagnosed in a patient who is less than 50 years of age. 2. Presence of synchronous, metachronous colorectal, or other HNPCC-associated tumors, regardless of age. 3. Colorectal cancer with the MSI-H histology diagnosed in a patient who is less than 60 years of age. 4. Colorectal cancer diagnosed in one or more first-degree relatives with an HNPCC-related tumor, with one of the cancers being diagnosed under age 50 years.