Efficacy of Capecitabine and Temozolomide Regimen in Neuroendocrine Tumors: Data From the Turkish Oncology Group

INTRODUCTION: This study aims to report the efficacy and safety of capecitabine plus temozolomide (CAPTEM) across different lines of treatment in patients with metastatic neuroendocrine tumors (NETs). METHODS: We conducted a multicenter retrospective study analyzing the data of 308 patients with metastatic NETs treated with CAPTEM between 2010 and 2022 in 34 different hospitals across various regions of Turkey. RESULTS: The median follow-up time was 41.0 months (range: 1.7-212.1), and the median age was 53 years (range: 22-79). Our results across the entire patient cohort showed a median progression-free survival (PFS) of 10.6 months and a median overall survival (OS) of 60.4 months. First-line CAPTEM treatment appeared more effective, with a median PFS of 16.1 months and a median OS of 105.8 months (median PFS 16.1, 7.9, and 9.6 months in first-, second- and ≥third-line respectively, P = .01; with median OS values of 105.8, 47.2, and 24.1 months, respectively, P = .003) In terms of ORR, the first-line treatment again performed better, resulting in an ORR of 54.7% compared to 33.3% and 30.0% in the second and third or higher lines, respectively (P < .001). Grade 3-4 side effects occurred only in 22.5% of the patients, leading to a discontinuation rate of 9.5%. Despite the differences in outcomes based on treatment line, we did not observe a significant difference in terms of side effects between the first and subsequent lines of treatment. CONCLUSIONS AND RELEVANCE: The substantial superior outcomes in patients receiving first-line CAPTEM treatment highlight its potential as an effective treatment strategy for patients with metastatic NET.