Introduction: Patients with neuroendocrine neoplasia (NEN) may experience psychological distress related to secretory effects of the tumour. 5-hydroxyindoleacetic acid (5-HIAA) is a metabolite of serotonin, the most important secretory product in carcinoid syndrome. This study aims to determine if urine 5-HIAA levels correlate with health-related quality of life (HRQoL) in patients with NEN.
Methods: A retrospective single-centre cohort study was conducted including 741 patients with a histological or radiological diagnosis of NEN. Patients at Kings Health Partners ENETS Centre of Excellence completed standardised questionnaires at clinic appointments. Temporally related spot urine 5-HIAA levels were correlated with PHQ-9 (depression), GAD-7 (anxiety), QLQ-GINET21 and EORTC QLQ-C30 scores. Correlation was evaluated with the Spearman rho test.
Results: 258 (34.8%) out of 741 patients had completed HRQoL data. Of these, 132 (51.2%) were male. 145 (56%) had a small intestine primary. The median age was 65 years (interquartile range, IQR: 54 - 72). Median urine 5-HIAA was 8.1 µmol/mmol (IQR: 4.0 - 13.6). Males had significantly higher (P =0.001) 5-HIAA (median:10.1, IQR: 6.2 - 16.2) compared to females (5.6, IQR: 3.3 - 11.6). Males also reported significantly higher Global Health Status (P= 0.018) and lower NET21 (P= 0.001), GAD-7 (P= 0.001) and PHQ-9 (P= 0.009) scores. Within the collective cohort, there was a significant association between high urine 5-HIAA levels and low GAD-7 (P= 0.037); similarly, between high urine 5-HIAA and low QLQ-GINET21 GI symptoms (P= 0.024). No significant association was found between urine 5-HIAA levels and EORTC QLQ-C30 Global Health Status (P= 0.527), EORTC QLQ-C30 diarrhoea score (P= 0.232), QLQ GINET21 endocrine symptoms scale (P= 0.151) and PHQ-9 (P= 0.515).
Conclusions: No significant correlation was detected between Urine 5-HIAA and patient reported depression (PHQ-9) or overall HRQoL (EORTC QLQ-C30 Global Health Status). The significant correlation between a low GAD-7 and high 5-HIAA may suggest high circulating levels of serotonin are associated with less anxiety. The sex differences in 5-HIAA values and HRQoL measures within this cohort warrants further studies to corroborate these findings.