290 - Definitive Stereotactic Body Radiation Therapy for Resectable Non-Metastatic Pancreatic Ductal Adenocarcinoma: A Multi-Center Retrospective Analysis
Presenter(s)
M. D. Chuong1, T. Kollipara2, R. Herrera1, J. M. Frakes3, M. Rubens4, K. Chau2, A. Kaiser1, S. Hoffe5, L. Vitzhum2, D. W. Kim6, D. T. Chang7, and E. L. Pollom8; 1Department of Radiation Oncology, Miami Cancer Institute, Miami, FL, 2Department of Radiation Oncology, Stanford University, Palo Alto, CA, 3Department of Radiation Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 4Department of Biostatistics, Miami Cancer Institute, Miami, FL, 5H. Lee Moffitt Cancer Center and Research Institute, Department of Radiation Oncology, Tampa, FL, 6Department of Medical Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 7Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 8Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA
Purpose/Objective(s): Most patients with resectable pancreatic ductal adenocarcinoma (PDAC) do not undergo surgery, often due to advanced age and/or medical comorbidities. Instead, they typically receive best supportive care (BSC), palliative chemotherapy (CT), or palliative radiation therapy (RT) that result in poor 2-yr overall survival (OS) ~10%. Definitive stereotactic body radiation therapy (SBRT) might achieve improved oncologic outcomes in this patient population.
Materials/Methods: We retrospectively analyzed consecutive patients with initially resectable non-metastatic PDAC who received definitive SBRT between 2006-2024 at 3 institutions in the United States. Clinical characteristics were compared using Chi square or Fisher’s exact test. Local control (LC) as per RECIST, progression free survival (PFS), and OS were estimated from diagnosis with the Kaplan-Meier method and log-rank test. Cox proportional hazards regression model was used for univariate (UVA) and multivariate (MVA) analysis.
Results: 74 patients with median age 81 years (range, 44-94 years) were evaluated. Most were male (59.5%), had tumor in the pancreatic head (87.8%), and were early-stage (73.0% T1-2, 86.5% N0 stage, 74.3% stage I-II). Median tumor size was 2.5 cm (range, 0.8-6.8 cm). ECOG performance status was 0-1 (78.5%) vs. 2-3 (18.9%). 50% received induction CT for a median 2.6 months (range, 0.2-15.5 months). The prescribed dose was 30-50 Gy in 5 fractions (91.9%) or 25 Gy in 1 fraction (8.1%); the median prescribed BED10 was 72 Gy (range, 37.5-100 Gy). Image guidance was kV/CBCT (59.5%) or MRI (40.5%); online adaptive RT (ART) was only used with MRI guidance. Median follow-up from diagnosis was 16.5 months. Median,1-yr, and 2-yr LC was not reached, 97.0% and 73.1%, respectively. Median, 1-yr, and 2-yr PFS were 17.0 months, 55.3%, and 24.6%, respectively. Median, 1-yr, and 2-yr OS were 17.0 months, 80.0%, and 27.8%, respectively. No significant factors were identified on MVA for LC. A trend towards higher OS on MVA was observed for longer induction CT duration (HR 0.496, 95% CI: 0.237-1.039; P=0.063), BED10 >72 Gy (HR 0.422, 95% CI: 0.175-1.016; P=0.054), and use of online ART (HR 0.382, 95% CI: 0.264-1.169; P=0.098). 2-yr OS was higher for BED10 >72 Gy vs. <=72 Gy (32.4% vs. 12.5%; P=0.041) and use of induction CT vs. no induction CT (35.9% vs. 18.9%, P=0.051). Acute and late grade 3+ adverse events were observed in 4.1% and 8.1% of patients, respectively.
Conclusion: Dose-escalated SBRT may achieve favorable OS with minimal toxicity for patients with medically inoperable PDAC. Optimizing selection criteria is crucial to identify the most appropriate candidates. Prospective evaluation of dose-escalated SBRT versus palliative CT/RT should be considered.