Background: Small-bowel neuroendocrine tumours (SB-NET) commonly metastasise despite most being low grade. The NET nomogram developed, estimates 5- and 10-year survival in SB-NET by allocating scores for 15 clinicopathological parameters. We comparatively evaluated the prognostic power of this nomogram, the WHO/ENETS grading and AJCC/UICC staging systems.
Methods: Patients with histologically-confirmed SB-NET were identified from databases at two tertiary centres. Demographics, tumour grade and stage, and additional biochemical/imaging data were extracted, as per the parameters in the NET nomogram. Nomogram scores for each patient were calculated, with survival estimates derived therefrom. Patients were categorised into low/medium/high-risk on the basis of nomogram scores. Kaplan-Meier methodology was used for all three systems to assess prognostic power.
Results: Seventy patients were identified (39 male, 31 female). Median age at diagnosis was 57 (range 3282). There were 62 (88.6%) G1, 6 (8.6%) G2 and 2 (2.8%) G3 tumours. Regarding tumour stage at presentation, 2 (2.8%), 3 (4.3%), 2 (2.8%), 19 (27.1%), and 44 (62.9%) had AJCC/UICC stage I, II, IIIa, IIIb and IV disease, respectively. There were no statistically significant differences in survival when patients were stratified by grade or stage (P=0.28; P=0.6). There were significant differences between survival when patients were stratified by nomogram scores: median survivals in low, medium and high risk tumours were 156, 129, and 112 months, respectively (P=0.031). When considering G1 tumours (all stages, n=62), disease stage was not associated with survival (P=0.33). Low-, medium- and high-risk G1 tumours had median survivals of 156, 129 and 62 months, respectively (P=0.005). Similar results were obtained in G1 IIIb/IV tumours (171, 143 and 126 months, respectively; P=0.006) and in G1 stage IV tumours (114, 129 and 62 months, respectively; P=0.035).
Conclusions: Predominantly, SB-NET are G1 but most present with nodal/distant metastases, hindering prognostication based purely on grade/stage. Our data demonstrate that multi-parametric assessment may translate into improved prognostication in SB-NET that otherwise would be erroneously predicted to exhibit similar clinical behaviour.
04 Dec 2017
UK and Ireland Neuroendocrine Tumour Society