Modified Histopathological Grading Optimizes Prediction of Survival Outcomes in Small Intestinal Neuroendocrine Tumours.

One of the major prognostic indices in neuroendocrine tumours (NETs) is Ki67 proliferation index. To identify optimal grading Ki-67 cut-offs to delineate differences in prognosis of patients with small intestinal NETs (SI-NETs). Multicentre retrospective cohort analysis of 551 SI-NET patients diagnosed from 1993 through 2021 at five European referral centres with a mean(±SD) follow-up time of 51.5(±52.9) months. Overall- and event-free survival (OS and EFS) rates. Median age at baseline was 62.3(range:17-90) years; 252(45.7%) patients were female. All SI-NETs were well-differentiated with 326 being grade 1(G1; 59.2%), 169G2(30.7%), and only 8G3(1.5), while 48 tumours were of unspecified grade (8.7%). The median Ki67 was 2%(range:1-70%). Two-hundred forty-seven patients (44.8%) had distant metastases at baseline (stage IV), 217 locoregional disease (41.1%; stage III), whereas 29(7.1%) and 25(4.5%) presented at stages II and I, respectively. The median OS was 214.7(95%CI:152.7-276.6) months and the median EFS was 79.8(95%CI:68.2-91.5) months, respectively. In multivariable Cox-regression OS analysis, the proposed modified histopathological Ki67 grading system (K67:5-10% group: HR=2.2, 95%CI:1.15-4.31; p=0.018 and K67≥10% group: HR=5.11, 95%CI:2.87-9.09; p<0.001), age (HR=1.07, 95%CI:1.04-1.09; p<0.001), Charlson Comorbidity Index (HR=1.08, 95%CI:1-1.16; p=0.028) and TNM stage (HR=1.79, 95%CI:1.05-3.06; p=0.034) were independent predictors for death. Pertinent EFS analysis, confirmed the proposed modified histopathological Ki67 grading system (K67≥10% group: HR=4.01, 95%CI:2.6-6.37; p<0.001) and age (HR=1.04, 95%CI:1.02-1.05; p<0.001) as independent predictors for recurrence, progression and/or death. Ki-67 proliferation index was a strong and independent predictor of OS and EFS. A modified histopathological grading system applying Ki-67 cut-offs of 5 and 10% could be superior to predict differences in SI-NET patient survival outcomes.

© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society.