More Cycles of Peptide-Based Radiation Therapy Linked to Longer Survival in Pancreatic Neuroendocrine Tumors | Research

The takeaway

Patients with metastatic pancreatic neuroendocrine tumors who received more cycles of peptide receptor radionuclide therapy (PRRT) lived significantly longer, especially those with lower-grade tumors and no bone metastases.

100 months median survival
Achieved by patients receiving 5 or more cycles of PRRT for metastatic pancreatic neuroendocrine tumors

What the researchers found

Among 166 patients with metastatic pancreatic neuroendocrine tumors, 100 received PRRT. Overall survival for the entire cohort was 79 months. Patients receiving 4 or more cycles of PRRT achieved a median overall survival of 87 months, while those receiving 5 or more cycles reached 100 months.

Tumor grade was a significant factor: patients with grade 1 or 2 tumors had a median survival of 97 months compared to 74.5 months for grade 3 tumors (p=0.0055). Bone metastases also predicted worse outcomes — patients with bone metastases who received PRRT survived a median of 74 months versus 89 months for those without (p=0.013). Whether the tumor was functioning or non-functioning did not significantly affect survival after PRRT.

Why it matters

PRRT is an established treatment for neuroendocrine tumors, but randomized trial data on its impact on overall survival has been lacking. This real-world study provides important evidence that extended PRRT courses are associated with longer survival, and identifies which patients — those with lower-grade tumors and no bone spread — benefit most. This information can help clinicians make better-informed treatment decisions.

How the study worked

The researchers conducted a retrospective analysis of 166 patients with histologically confirmed metastatic pancreatic neuroendocrine tumors. Of these, 100 received PRRT with a median of four cycles. Survival outcomes were analyzed by subgroups based on tumor grading, tumor functionality (hormone-secreting vs. non-secreting), and presence of bone metastases.

What this study cannot tell us

This was a retrospective study from a single center, which limits the ability to draw causal conclusions. The survival benefit of more PRRT cycles may partly reflect selection bias — healthier patients are more likely to tolerate and complete more treatment cycles. There was no randomized control group, and 19% of PRRT patients discontinued due to disease progression, toxicity, or death. The study also did not detail specific PRRT regimens or radionuclides used.

How to read the evidence

This is a retrospective single-center observational study with 166 patients. While it provides valuable real-world survival data, the lack of randomization and potential selection bias mean the results should be interpreted cautiously. The sample size is moderate for this relatively rare cancer type.

When this study was published

Published in 2025, this study provides recent real-world data on PRRT outcomes and remains highly relevant to current clinical practice for neuroendocrine tumors.

The bigger picture

PRRT has become a key treatment option for neuroendocrine tumors, but optimal treatment duration and patient selection criteria remain active areas of research. This study adds to evidence that more PRRT cycles may improve outcomes and highlights the importance of tumor grade and metastasis patterns in predicting treatment response. As peptide-based targeted therapies continue to evolve, these real-world data help refine who benefits most.

Questions still open

Would a prospective randomized trial confirm the survival benefit of 5 or more PRRT cycles over fewer cycles?
Can the addition of other treatments alongside PRRT improve outcomes for patients with grade 3 tumors or bone metastases?
What biomarkers beyond grade and metastasis location could help predict which patients will respond best to extended PRRT?

Common questions

What is peptide receptor radionuclide therapy (PRRT)?

PRRT is a targeted cancer treatment that attaches radioactive molecules to peptides that bind specifically to receptors on tumor cells. This delivers radiation directly to the tumor while minimizing damage to surrounding healthy tissue. It is most commonly used for neuroendocrine tumors that express somatostatin receptors.

Why did patients with bone metastases have worse outcomes?

Bone metastases generally indicate more advanced disease spread. Tumors that have spread to bone may be more aggressive or resistant to treatment. In this study, patients with bone metastases who received PRRT survived a median of 74 months compared to 89 months for those without bone involvement, suggesting that bone spread is an important prognostic factor.

Read the original research

Impact of functionality and grading on survival in pancreatic neuroendocrine tumor patients receiving peptide receptor radionuclide therapy.

Frontiers in endocrinology, 16, 1526470

View on PubMed ↗Publisher’s paper ↗

Citation

Mathew, Annie; Kersting, David; Fendler, Wolfgang P; Braegelmann, Johanna; Fuhrer, Dagmar; Lahner, Harald. (2025). Impact of functionality and grading on survival in pancreatic neuroendocrine tumor patients receiving peptide receptor radionuclide therapy.. Frontiers in endocrinology, 16, 1526470. https://doi.org/10.3389/fendo.2025.1526470