Transanal endoscopic microsurgery yields better long term outcomes in rectal neuroendocrine tumors

China: When it comes to the treatment of tiny rectal neuroendocrine tumors (RNET), transanal endoscopic microsurgery (TEM) provides good long-term results and minimal anal function disruption. Incomplete endoscopic excision is also a good candidate for TEM as salvage therapy, says a study published in BMC Surgery.

TEM is widely used to treat local rectal lesions all around the world. Wei-Kun Shi and colleagues set out to evaluate the effectiveness and safety of TEM in the treatment of RNET in this study.

Patients who received TEM for RNET at Peking Union Medical College Hospital, Bejing, China between December 2006 and June 2019 were studied retrospectively. Anal function surveys, demographic and tumour features, surgical and pathological information, complications, and follow-up data were all included.

The key findings of this study were as follow:

1. A total of 144 patients were enrolled in the study. In 54 cases, TEM was used as the main excision, 57 patients had endoscopic forceps biopsy, and 33 patients had incomplete resection by endoscopic excision.

2. The median size of all initial tumors was 0.6 cm, and 142 patients had a negative resection margin.

3. Three patients had postoperative problems, which were effectively handled using a conservative approach.

4. Three patients died of other reasons after a median follow-up of 75.5 months following surgery, and two patients developed metastases.

5. 24 months following the TEM, an anal function questionnaire was presented. Three patients (2.1%) experienced significant low anterior resection syndrome (LARS), including one (0.7%) who had full incontinence, while six patients (4.2%) had minor LARS.

6. Five months after TEM, one patient in the biopsy group had local metastases, necessitating extensive surgery. The pathological grade of the lymphatic metastasis-positive tumor was G2, however the biopsy material and tumor tissue removed via TEM were both G1, indicating that this tumor was likely made up of two grades, with G1 being the majority.

In conclusion, TEM is a successful treatment for RNET less than 2 cm in size, however it has a deleterious impact on anal function. Positive margins following endoscopic resection are suitable candidates for TEM.

Reference:

Shi, WK., Hou, R., Li, YH. et al. Long-term outcomes of transanal endoscopic microsurgery for the treatment of rectal neuroendocrine tumors. BMC Surg 22, 43 (2022). https://doi.org/10.1186/s12893-022-01494-2