The Role of Stereotactic-Body-Radiation-Therapy in Neuroendocrine Pancreatic Tumors

Abstract

Introduction: Surgery is standard treatment for pancreatic-neuroendocrine-tumors (TNP) although it is occasionally associated with high-rates of morbid-mortality. Radiotherapy can be an effective alternative in selected patients. Our objective is to evaluate the efficacy of SBRT (Stereotactic-body-radiation-therapy) as a radical treatment for TNP. Materials and Methods: Between December 2017 and November 2020, we prospectively analyzed 13 patients with pathological diagnosis of TNP of <2cm treated with SBRT as a part of an IRB-approved study. The endpoints of the study are local-control, tolerance, progression-free-survival and overall-survival. Before SBRT, two internal fiducial markers were placed into the tumor by endoscopic ultrasound puncture and a simulation-CT was obtained. Clinical-target-volume (CTV) included pancreatic tumor. Planning-target-volume (PTV) was CTV with 5mm expansion. Patients received 40Gy in 5 fractions on every other day. Results: Patients’ characteristics: 6 female (46%) and 7 males (54%) with a mean age of 55.6 years-old. Tumor location: head 3p (23%), neck 3p (23%), body 6p (46%) and tail of pancreas 1p (8%). Octreoscan prior to radiotherapy was positive in 8p (61.5%). FDG-PET was negative for all but one patient (SUV <4). With a median follow-up of 13.6 months (range 1.8- 34.4), all patients are without evidence of relapse. Acute tolerance was excellent. Only 3p (23%) showed asthenia. One p developed peptic ulcer on follow-up. Conclusions: SBRT is feasible and well tolerated and could be an alternative in selected patients with diagnoses of TNP, although further studies are necessary.