Rectal neuroendocrine tumor (G1) with widespread metastasis 8 years after endoscopic resection

AbstractRectal neuroendocrine tumor (NET) G1 is a docile-looking tumor. We herein report a 77-year-old male whose rectal NET G1 measuring 10 mm recurred eight years after endoscopic mucosal resection. Tumor recurrence was detected by his mild general fatigue. Abdominal computed tomography revealed widespread metastasis, including the liver, lymph nodes around the rectum, and cervical spines. Subsequent somatostatin receptor scintigraphy, as well as histological reassessment of previously resected specimen, proved that these metastatic diseases originated from the rectal NET G1 with vascular invasion and possible positive vertical margin. First, octreotide long-acting repeatable 30 mg i.m. was administered every four weeks. Second, transcatheter arterial chemoembolization (TACE) for multiple liver metastases and irradiation therapy for spinal metastasis were carried out. One year after these treatments started, everolimus (mTOR inhibitor) 10 mg p.o. was administered every day. For the last five years, he received two rounds of TACE treatments and one round of irradiation. Although recurrent diseases were temporally controlled by these multidisciplinary treatments for the last month, he died of multiple metastases six years later, after tumor recurrence was detected. This case underscores the potential for late recurrence even in rectal NET G1 with unfavorable histological features, highlighting the importance of long-term surveillance.