Comparative analysis of streptozocin-based regimen and capecitabine-temozolomide therapy in advanced pancreatic neuroendocrine neoplasms: influence of tumor grade and Ki-67 index.

BACKGROUND

Systemic therapy is a standard treatment option for pancreatic neuroendocrine neoplasms (Pan-NENs) with unresectable or metastatic disease. Streptozocin (STZ)-based chemotherapy is considered a standard treatment option for tumors with a high Ki-67 index or for cases refractory to molecular targeted agents. More recently, the combination of capecitabine and temozolomide (CAPTEM) therapy has emerged as a new treatment option.

OBJECTIVES

This study aimed to compare the efficacy, safety, and clinical outcomes between the STZ-based regimen and CAPTEM therapy in patients with unresectable or metastatic Pan-NENs.

DESIGN

This was a single-center retrospective study of histologically confirmed Pan-neuroendocrine tumor (NET) patients treated with either STZ-based regimens or CAPTEM between November 2015 and June 2024.

METHODS

We compared efficacy, safety, and clinical outcomes between the two regimens. Tumor responses were assessed using Response Evaluation Criteria in Solid Tumors version 1.1, and adverse events were graded according to Common Terminology Criteria for Adverse Events version 5.0. The study was conducted in compliance with the STROBE guidelines.

RESULTS

Of the 371 patients diagnosed with Pan-NENs, 47 received STZ-based regimen and 21 received CAPTEM therapy. In the NET-G1/G2 patients, the STZ group showed a significantly higher tumor shrinkage rate compared to CAPTEM therapy. Although no significant differences were observed in progression-free survival (PFS) or overall survival between the two groups, subgroup analysis showed that the median PFS in the STZ group was significantly longer than that in the CAPTEM group in NET G1/G2 patients. Renal dysfunction was the main adverse event in the STZ regimen group, while gastrointestinal symptoms were common in the CAPTEM therapy group; however, both were manageable.

CONCLUSION

Both STZ-based regimen and CAPTEM therapy are safe and effective treatment options for advanced Pan-NENs. STZ-based regimen was more beneficial in NET-G1/G2 patients, suggesting Ki-67 index and tumor grade may serve as indicators for treatment selection. Further prospective studies are warranted to validate these findings.