Increase of angiogenic growth factors after hepatic artery embolization in patients with neuroendocrine tumours

In the event of diffuse hepatic metastases, hepatic artery embolization (HAE) can be a successful treatment option in patients with well-differentiated neuroendocrine tumours (NET). However, embolization causes hypoxia which stimulates angiogenesis and therefore tumour growth. This study investigates angiogenesis activity following HAE by measuring vascular endothelial growth factor (VEGF), endothelin-1 (ET-1) and C-terminal proendothelin-1 (proET-1) in blood. Twelve patients with well-differentiated NET and liver metastases underwent HAE. VEGF, ET-1 and proET-1 were measured before embolization and the days following treatment during hospitalization. Mean levels during treatment were compared with those at baseline. From 12 patients, 90 blood samples were obtained before and daily for 8 days following HAE. Mean (±SE) VEGF level at baseline was 116 (±33) ng/l which increased after HAE to 313 (±46) ng/l at day 6, followed by a gradual decrease. ProET-1 showed a similar pattern, with a mean baseline level of 9.2 (±2.0) pmol/l and the highest level of 40.8 (±5.7) pmol/l at day 6. Some fluctuations were observed for ET-1, with maximum levels at day 3 compared to baseline levels. In patients with well-differentiated NET who underwent hepatic arterial embolization, angiogenic growth factors increase temporarily. This implies a need to investigate the effect of anti-angiogenic drugs as an adjuvant therapy to embolization.