The ENETS TNM staging and grading system accurately predict prognosis in patients with rectal NENs

Abstract Background Factors associated with rectal NENs prognosis are poorly investigated. Aim To evaluate the prognostic role of the ENETs staging and grading systems in rectal NENs. Methods Tertiary referral, multicenter, retrospective study. Factors associated with OS and PFS were investigated by Cox-regression analysis, with best size cut-offs calculated by ROC analysis. Results Of 100 patients (mean age 55, 45% male, mean size 16.2 mm) 62, 5, 10 and 23 were TNM stage 1 to 4, and 63, 15 and 22 were G1, G2 and G3. Primary treatment was endoscopic snare resection in 62%, endoscopic mucosal resection/endoscopic submucosal dissection in 10%, surgery in 20% and medical treatment in 8%. The best size cut-offs to predict OS and PFS were 10 and 12 mm. During a mean follow-up of 40.7 months 12% died and 26% progressed. The 5-year OS and PFS were 79.5% and 65.2%. Stage IV and G3 were associated with worse OS (HR 8.16; p = 0.002; HR 15.57; p = 0.0004) and PFS (HR 14.26 p  Conclusion Both staging and grading accurately predict rectal NENs prognosis. Size alone has limited accuracy as 26% of patients with stage IV and 16% with G3 have a primary tumour≤10 mm.