Long-term Survival Outcomes from Integrating Yttrium-90 Radioembolization with Capecitabine-Temozolomide for Grade 2 Liver-Dominant Metastatic Neuroendocrine Tumors

Objective: This study reports long-term survival statistics from a sample of patients who were treated concomitantly with Yttrium-90 radioembolization (y90) and systemic Capecitabine-Temozolomide (CapTem) for grade 2 liver-dominant metastatic neuroendocrine tumors.

Methods: Twenty-five patients with unresectable grade 2 NET liver-dominant metastases without contraindications to radioembolization or to CapTem initiated therapy with capecitabine 600mg/m2 twice daily for 14 days and temozolomide 150 to 200 mg/m2 in 2 divided doses on days 10 to 14, with 12 days between cycles. The dominant lobe was then radioembolized on day 7 of the second cycle. These patients were then followed with contrast enhanced MRI of the abdomen to evaluate for recurrent disease using the RECIST criteria.

Results: Median progression-free survival (PFS) was 38 months (95% CI 23-62 months), with PFS at 1 and 2 years being 87% and 67%, respectively. Median hepatic progression-free survival (HPFS) was 52 months (95% CI 23-68 months), with HPFS at 1 and 2 years being 83% and 67%, respectively. There was no significant difference in PFS or HFPS when stratified between primary pancreatic neuroendocrine tumors and other histologies, with hazard ratios of 1.52 (0.53-4.33, p=0.44) and 0.96 (0.29-3.16, p=0.95), respectively.

Conclusions: CapTemY90 appears to provide a synergistic effect, exceeding the expected PFS for G2 neuroendocrine tumors.