Quantitative dual-layer spectral CT parameters associated with a continuous improvement response pattern to CAPTEM in advanced gastroenteropancreatic neuroendocrine neoplasms.

OBJECTIVES: To evaluate the prognostic significance of a dynamic continuous improvement (CI) response pattern in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) treated with capecitabine and temozolomide (CAPTEM), and to explore the association between baseline dual-layer spectral CT (DLCT) parameters and this favorable response trajectory. METHODS: This single-center retrospective study (May 2016 - September 2025) analyzed 54 patients treated with CAPTEM. Cox proportional hazards regression models were used to identify prognostic factors affecting progression-free survival (PFS). Patients were stratified via 9-month landmark analysis into CI and non-continuous improvement (NCI) groups. PFS and Time to Nadir (TTN) were compared. Baseline DLCT parameters were analyzed for their association with the CI pattern. RESULTS: 54 patients (median age, 53 years; 29 men) were evaluated. Peritumoral tissue invasion was independent prognostic factor (p = 0.008; Hazard Ratio [HR], 4.604; 95% confidence interval: 1.495, 14.173). In the landmark cohort, post-landmark PFS was significantly longer in the CI (n = 9) than the NCI (n = 13) group (18.70 vs. 6.47 months; HR, 0.295; 95% confidence interval: 0.100, 0.876; p = 0.044), with a longer TTN (9.67 vs. 6.83 months; p = 0.021). Lower baseline nIC and Zeff values were significantly associated with the CI pattern (median Zeff 8.070 vs. 8.920, p = 0.008; median nIC 0.426 vs. 0.723, p = 0.030). CONCLUSION: The continuous improvement response pattern was associated with prolonged PFS in GEP-NENs treated with CAPTEM. Baseline DLCT parameters may help identify patients likely to derive sustained benefit from CAPTEM therapy.