OBJECTIVE: To determine if urinary 5-hydroxyindoleacetic acid (5-HIAA) excretion is of prognostic value for overall survival (OS) in patients with a gastrointestinal neuroendocrine tumour (NET) and to compare the prognostic value with patient characteristics, ENETS/WHO grading, ENETS TNM staging and biomarkers.DESIGN AND METHODS: Data was collected from patients with a gastrointestinal NET or a NET with gastrointestinal metastases and available 5-HIAA excretion in 24-h urine samples. Laboratory results were stratified for urinary 5-HIAA and chromogranin A (CgA): <2? upper limit of normal (ULN), 2-10? ULN, or >10? ULN. For neuron-specific enolase (NSE), this was the reference range or >1? ULN. OS was compared using Kaplan-Meier and log-rank tests, and hazard ratios were calculated using Cox regression for univariate and multivariate analyses.RESULTS: A total of 371 patients were included, 46.6% female with a mean age of 59.9 years. OS was shortest in patients with urinary 5-HIAA excretion >10? ULN vs reference range (median 83 months vs 141 months, P = 0.002). In univariate analysis, urinary 5-HIAA excretion >10? ULN was a negative predictor (HR 1.62, 95% CI: 1.09-2.39). However, in multivariate analysis, only age (HR 1.04, 95% CI: 1.01-1.08), grade 3 disease (HR 5.09, 95% CI: 2.20-11.79), NSE >1? ULN (HR 2.36, 95% CI: 1.34-4.14) and CgA >10? ULN (HR 3.61, 95% CI: 1.56-8.34) remained as the predictors.CONCLUSION: Urinary 5-HIAA excretion >10? ULN is a negative predictor for OS. However, when added to other biomarkers and grading, it is no longer a predictor for OS. Therefore, it should only be determined to assess carcinoid syndrome and not for prognostic value.
Aged Biomarkers, Tumor