Abstract
Current biomarkers do not adequately predict the behaviour of neuroendocrine neoplasms (NENs). This study assessed the NETest, a multianalyte blood biomarker, in patients with small intestinal NENs (Si-NENs). We studied two patient groups: Group 1: metastatic Si-NENs (n = 102) and Group 2: post-operatively disease-free according to 68Ga-DOTATATE PET (n = 16). NETest scores were ≤20% (normal), 21-40% (low), 41-79% (intermediate), or ≥80% (high). Overall survival (OS) and progression-free survival (PFS) were assessed using the Kaplan-Meier method. Univariate and multivariate analyses were performed using the Cox proportional hazards model. In Group 1, the median NETest score was 40% (IQR: 33.3-46.7%). The NETest value (HR: 1.032, 95% CI: 1.003-1.062, p = 0.033) and high-risk NETest category (HR: 10.5, 95% CI: 1.35-81.7, p = 0.025) were independent predictors of PFS, along with presence of lung metastases, CgA levels > 10 × ULN, and tumour growth rate (TGR). Independent predictors of OS were the NETest value (HR: 1.035, 95% CI: 1.005-1.066, p = 0.024) and high-risk NETest category (HR: 15.2, 95% CI: 1.52-151, p = 0.02), along with presence of lung metastases and CgA levels > 10 × ULN. In Group 2, ROC analysis identified an AUC of 0.909 (95% CI: 0.75-0.100) for prediction of local or metastatic recurrence. Blood NETest scores were associated with PFS and OS in patients with metastatic Si-NENs, along with TGR, CgA > 10 × ULN, and presence of lung metastases.