Local Excision Versus Radical Resection for Grade 2 Rectal Neuroendocrine Tumors: A Multicenter Propensity Score-Matched Analysis.

BACKGROUND:Studies on the grade 2 rectal neuroendocrine tumors are limited and the optimal treatment for these tumors is not well established. OBJECTIVE:To compare the oncologic results of local excision versus radical resection for the treatment of grade 2 rectal neuroendocrine tumors. DESIGN:Retrospective multicenter propensity score-matched study to minimize heterogeneity between groups and focus on the difference between surgery strategies. SETTINGS:Seventeen Chinese large-scale medical centers participated in this study. PATIENTS:A total of 144 patients with pathologically confirmed grade 2 rectal neuroendocrine tumors were retrospectively analyzed. MAIN OUTCOME MEASURES:Cancer-specific survival and relapse-free survival were assessed to compare surgery strategies. RESULTS:A total of 144 patients with grade 2 rectal neuroendocrine tumors were enrolled in this study. Twenty-seven patients underwent endoscopic resection, 55 underwent transanal excision, 50 underwent radical resection, and 12 underwent palliative surgery or biopsy for distant metastasis. Of the 50 patients who underwent radical resection, 30 (60.0%) had clinically positive lymph nodes based on the histopathology results. The optimal cutoff value for tumor size to predict cancer-specific survival was 1.5 cm. In patients with grade 2 rectal neuroendocrine tumors ≤ 1.5 cm, there were no significant differences in cancer-specific survival and relapse-free survival between local excision and radical resection groups (P >0.05). In patients with grade 2 rectal neuroendocrine tumors > 1.5 cm, relapse-free survival was significantly lower in the local excision group than in the radical resection group (P = 0.04). LIMITATIONS:The nature of retrospective review and relatively short follow-up period are limitations of this study. CONCLUSIONS:Grade 2 rectal neuroendocrine tumors have a nonnegligible rate of lymph node metastasis. Local excision is a feasible choice for tumors ≤ 1.5 cm without metastasis, while radical resection is more beneficial in those > 1.5 cm. See Video Abstract.