Introduction
The incidence of rectal neuroendocrine tumors (rNETs) has risen over the past two decades, largely due to the increased use of endoscopic procedures. These tumors are typically small, well-differentiated, and associated with a favorable prognosis. However, up to 82% may be misdiagnosed, leading to inadequate treatment. Accurate staging and appropriate management are essential for achieving long-term, progression-free survival (PFS) [1-2].
Aims & Methods
This study evaluates the clinical outcomes of patients with rNETs ≤1 cm who underwent local excision.
This retrospective, dual-center study included patients with rNETs measuring ≤10 mm who underwent local excision. The primary endpoint was PFS. Resection techniques were categorized into two groups based on guideline recommendations: recommended (m-EMR, ESD, EFTR, and TAMIS/TEMS) or not recommended (biopsy forceps and hot/cold snare polypectomy). Statistical analyses were performed using MedCalc software, with significance set at p < 0.05.
Results
Among 101 patients initially evaluated, 91 were included after excluding 10 due to incomplete endoscopic follow-up. The cohort consisted of 51 men (56%) and 40 women (44%), with a median age of 53 years. The median tumor size was 5 mm (range: 1–10 mm). Tumor grading was G1 in 93.4% of cases and G2 in 6.6%, with a median Ki-67 index of 2%.
Recommended resection techniques were used in 34 patients (37.4%), while 57 patients (62.6%) underwent non-recommended methods. Positive R1 resection margins were found in 27 cases (29.7%), and lymphovascular invasion was detected in two cases. Tumor progression (defined as recurrence, increase in residual tumor following R1 resection, or development of metastasis) occurred in 15 patients (16.5%), with only one case progressing to lymph node metastasis (median time to progression: 14 months [1–108 months]). Two deaths were recorded, neither related to the tumor. The median progression-free survival was 28 months (range: 1–170 months).
Univariate analysis showed that the use of recommended resection techniques significantly improved prognosis (HR 0.12, p = 0.04).
Conclusion
Although rNETs measuring ≤10 mm can recur, their risk of metastatic progression remains low, confirming their indolent behavior. However, early detection and the choice of appropriate resection techniques are essential for optimizing patient outcomes. Guideline-recommended resection methods are linked to a lower risk of progression and should be the preferred approach in clinical practice.
References
1. Rinke A, Ambrosini V, Dromain C, Garcia-Carbonero R, Haji A, Koumarianou A, van Dijkum EN, O'Toole D, Rindi G, Scoazec JY, Ramage J. European Neuroendocrine Tumor Society (ENETS) 2023 guidance paper for colorectal neuroendocrine tumours. J Neuroendocrinol. 2023 Jun;35(6):e13309.
2. Fine C, Roquin G, Terrebonne E, Lecomte T, Coriat R, Do Cao C, de Mestier L, Coffin E, Cadiot G, Nicolli P, Lepiliez V, Hautefeuille V, Ramos J, Girot P, Dominguez S, Céphise FV, Forestier J, Hervieu V, Pioche M, Walter T. Endoscopic management of 345 small rectal neuroendocrine tumours: A national study from the French group of endocrine tumours (GTE). United European Gastroenterol J. 2019 Oct;7(8):1102- 1112.
