Stereotactic Body Radiotherapy in the Treatment of Advanced Adenocarcinoma of the Pancreas

Objectives: The aim of the study was to assess the feasibility and safety of stereotactic body radiotherapy (SBRT) in patients with advanced pancreatic adenocarcinoma. Methods: We reviewed outcomes of 71 patients treated with SBRT for pancreatic cancer between July 2004 and January 2009. Forty patients (56%) had locally unresectable disease, 11 patients (16%) had local recurrence following surgical resection, 8 patients (11%) had metastatic disease, and 12 patients (17%) received adjuvant SBRT for positive margins. The median dose was 24 Gy (18-25 Gy), given in a single-fraction SBRT (n = 67) or fractionated SBRT (n = 4). Kaplan-Meyer survival analyses were used to estimate freedom from local progression (FFLP) and overall survival (OS) rates. Results: The median follow-up among surviving patients was 12.7 months (4-26 months). The median tumor volume was 17 mL (5.1-249 mL). The overall FFLP rates at 6 months/1 year were 71.7%/48.5%, respectively. Among those with macroscopic disease, FFLP was achieved in 77.3% of patients with tumor size <15 mL (n = 22), and 59.5% for >= 15 mL (n = 37) (P = 0.02). FFLP was achieved in 73% following 24 to 25 Gy, and 45% with 18 to 22 Gy (P = 0.004). The median OS was 10.3 months, with 6 month/1 year OS rates of 65.3%/41%, respectively. Grade 1-2 acute and late GI toxicity were seen in 39.5% of patients. Three patients experienced acute grade 3 toxicities. Conclusions: SBRT is feasible, with minimal grade >= 3 toxicity. The overall FFLP rate for all patients was 64.8%, comparable to rates with external beam radiotherapy. This shorter treatment course can be delivered without delay in adjuvant systemic therapy.