appropriate surgical management for non–PNETS (carcinoid tumors)
Gastric carcinoids are classified into three types. Types I and II account for most gastric carcinoids (> 75%) and are associated with chronic hypergastrinemia resulting from chronic atrophic gastritis (type I) and ZES (type II), respectively. These tumors are most commonly small (< 1 cm) and multifocal and are typically treated by endoscopic resection and surveillance with excellent outcomes. Octreotide or lanreotide therapy can control symptoms in patients with type II gastric carcinoids and ZES. Type III gastric carcinoids occur sporadically and are usually larger, solitary, and invasive. They are treated similarly to gastric adenocarcinoma with formal gastric resection and lymph node dissection. For tumors < 2 cm in size, endoscopic or wedge resection is possible.
Small intestinal carcinoids without metastases should be excised by segmental resection and lymph node dissection. Some studies advocate the use of prophylactic octreotide (preoperative bolus and/or continuous infusion) during surgery for foregut and midgut carcinoids to prevent carcinoid crisis; however, this remains controversial because some studies have shown it to be ineffective. Appendiceal carcinoids are typically incidentally discovered and occur most commonly at the appendiceal tip. Distal lesions < 2 cm are adequately treated with appendectomy. The presence of a carcinoid tumor near the appendiceal base, size > 2 cm, or gross lymph node involvement requires a formal right hemicolectomy. Rectal carcinoids often manifest with bleeding or are incidentally found on endoscopy. Tumors < 1 cm can be subjected to endoscopic resection, tumors 1 to 2 cm to transanal excision, and tumors > 2 cm or with evidence of lymph node metastasis on endoscopic ultrasonography to surgical resection (low anterior resection or abdominoperineal resection).