Stereotactic body radiation therapy for nonresectable tumors of the pancreas

Background: Stereotactic body radiation therapy (SBRT) has emerged as a potential treatment option for local tumor control of primary malignancies of the pancreas. We report on our experience with SBRT in patients with pancreatic adenocarcinoma who were found not to be candidates for surgical resection. Methods: The prospective database of the first 20 consecutive patients receiving SBRT for unresectable pancreatic adenocarcinomas and a neuroendocrine tumor under an IRB approved protocol was reviewed. Prior to SBRT, cylindrical solid gold fiducial markers were placed within or around the tumor endoscopically (n = 13), surgically (n = 4), or percutaneously under computerized tomography (CT)-guidance (n = 3) to allow for tracking of tumor during therapy. Mean radiation dose was 25 Gray (Gy) (range 22-30 Gy) delivered over 1-3 fractions. Chemotherapy was given to 68% of patients in various schedules/timing. Results: Patients had a mean gross tumor volume of 57.2 cm ³ (range 10.1-118 cm ³) before SBRT. The mean total gross tumor volume reduction at 3 and 6 mo after SBRT were 21% and 38%, respectively (P < 0.05). Median follow-up was 14.57 mo (range 5-23 mo). The overall rate of freedom from local progression at 6 and 12 mo were 88% and 65%. The probability of overall survival at 6 and 12 mo were 89% and 56%. No patient had a complication related to fiducial markers placement regardless of modality. The rate of radiation-induced adverse events was: grade 1-2 (11%) and grade 3 (16%). There were no grade 4/5 adverse events seen. Conclusion: Our preliminary results showed SBRT as a safe and likely effective local treatment modality for pancreatic primary malignancy with acceptable rate of adverse events.