S3814 Metastatic Colorectal Adenocarcinoma Presenting as Copremesis

Introduction: Early-onset colorectal cancer (EOCRC) is colorectal cancer diagnosed in individuals under the age of 50. EOCRC accounts for approximately 10% of all new colorectal cancer cases. While colon cancer can manifest with various symptoms, the development of a gastrocolonic fistula is an uncommon initial presentation. Case Description/Methods: A 39-year-old man presented with the chief complaint of abdominal pain for the past 2 weeks before presentation and foul-smelling burps. Patient reported a 45-pound weight loss over 6 months but reported normal bowel function. He denied any family history of known colon cancer or inflammatory bowel disease. Computed tomography scan of abdomen/pelvis revealed findings concerning gastrocutaneous fistula with significant wall thickening of the distal transverse colon and fistulous connection to the greater curvature of the stomach. Patient was started on TPN due to prolonged malnutrition. Genetic testing was done which showed pathogenic mutation, cardiac pathogenic mutation detected PQ287. Patient underwent upper GI endoscopy which showed esophageal ulcer with no bleeding which was biopsied, nonobstructing oozing gastric ulcer which was deep and appeared to be consistent with fistula and a probable malignant gastric lesion of undetermined etiology complicated by possible fistulous tract. Patient underwent colonoscopy which showed 2 pedunculated and semi sessile polyps in the sigmoid colon of 10 to 17 mm in size and multiple pedunculated and sessile and semi pedunculated polyps in the descending colon which were large in size. A fungating and ulcerated completely obstructing large mass was found in the transverse colon–the mass was circumferential and oozing was present. Biopsy showed metastatic colorectal adenocarcinoma to stomach and invasive well-differentiated adenocarcinoma transverse colon. Positron emission tomography scan did not reveal any evidence of distant metastatic disease. Patient's colon cancer was staged as stage IIIc with TNM classification of pT4b, pN1b, cM0. Patient underwent left hemicolectomy with creation of colocolonic anastomosis and partial gastrectomy en bloc by surgical oncology. Patient was started on adjuvant chemotherapy and it was recommended that patient's children start screening colonoscopy at age 29. Discussion: This case highlights an unusual presentation of early-onset colorectal cancer, emphasizing the importance of a thorough patient history, timely imaging, and appropriate treatment in diagnosing and managing colon cancer.