Treatment of localized well-differentiated rectal neuroendocrine tumors: A focused review

Abstract

The frequency of rectal neuroendocrine tumors increases with the increase in the number of colonoscopies performed for colorectal cancer screening. The treatment of localized rectal well-differentiated neuroendocrine tumors involves local excision, including endoscopic treatment or rectal resection with lymphadenectomy. Although it is important to determine the risk of lymph node metastasis, there are points of disagreement among the guidelines regarding surgical indications. In this review, we discuss the current status of the treatment of well-differentiated rectal neuroendocrine tumors. The PubMed database was searched for relevant studies. In Japan, the criteria for curative endoscopic resection are very strict: less than 10 mm, G1, no invasion of the muscularis propria, no suspicion of lymph node metastasis, and no lymphovascular invasion. Meanwhile, in Western guidelines, local excision (endoscopic treatment is preferable) is recommended as the initial treatment for tumors measuring ≥10 mm and <20 mm in diameter, and radical surgery is recommended for tumors ≥20 mm in diameter. There are still many points where evidence is lacking, and future research is warranted.