 This study is a multi-center, prospective, non-interventional NI study evaluating the safety and efficacy of sunitinib in Chinese patients with progressive, unresectable, advanced or metastatic well-differentiated, pancreatic neuroendocrine tumorspNET. 100 adults with progressive advanced or metastatic well-differentiated unresectable pNET will be recruited in China hospitals. Each subject will be followed up overall survival OS time or the date of withdrawal and subjects who remain alive after study completion will have their OS time censored on the last date known to be alive. Eligible subjects will be enrolled to receive at least one dose of sunitinib orally at 37.5 mg once a day on a continuous daily dosing regimen CDD or dosage modification is based on daily clinic practice. Subjects will be treated until disease progress, unacceptable toxicity, withdrawal from the study at their own request, or until the final analysis for the study is performed. The NI study will capture observations that will be used for evaluating the safety profile of sunitinib, including: subject demographics, medical history and medications. Safety assessments, treatment data and any other laboratory examination results, which were done according to routine clinical practice, will be collected at all visits. 