Which drug first? study seeks best order for neuroendocrine tumor therapy

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Histopathologically confirmed locally advanced unresectable, metastatic, or postoperative recurrent neuroendocrine tumors (NETs), any primary site. * Grade G1 or G2 based on Ki-67 index and/or mitotic count. * Somatostatin receptor 2 (SSTR2) positive confirmed by immunohistochemistry (IHC) or somatostatin receptor imaging (e.g., 68Ga-PET/CT). * Received one of the following two sequential treatment patterns: Cohort A (Surufatinib → SSA): First-line surufatinib monotherapy followed by second-line long-acting somatostatin analog (SSA; lanreotide or octreotide long-acting release formulation) after disease progression. Cohort B (SSA → Surufatinib): First-line long-acting SSA monotherapy followed by second-line surufatinib after disease progression. * Each line of treatment duration at least 1 cycle (surufatinib ≥4 weeks; SSA ≥1 injection). * Complete baseline clinical data, treatment start/end dates, and serial imaging evaluation reports available to determine progression-free survival for each line. * Age ≥18 years at first-line treatment initiation. * Permitted concomitant treatments during study drug administration (not considered as exclusion criteria): Best supportive care (e.g., antidiarrheals, analgesics, hepatoprotective agents, symptomatic treatment for hormone secretion). Local palliative interventions for focal lesions (e.g., transarterial embolization/chemoembolization, ablation for liver metastases) or cytoreductive surgery, provided they do not interrupt systemic study treatment or violate protocol. For functional NETs, short-acting somatostatin analogs as rescue therapy for symptom control (frequency and dose to be recorded). Exclusion Criteria: * Received any combined systemic therapy (e.g., chemotherapy, other targeted therapy, immunotherapy) in addition to surufatinib or SSA during first-line or second-line treatment. * Missing key baseline data (e.g., pathological grade, primary tumor site) or incomplete treatment/follow-up imaging data precluding accurate assessment of progression-free survival. * Presence of active, uncontrolled serious infection or another active malignancy at the start of first-line treatment that may interfere with assessment of neuroendocrine tumor progression or patient survival prognosis (except cured skin basal cell carcinoma or carcinoma in situ).