Presenter(s)
M. Loi1, M. Valzano1, M. Aquilano1, P. Bonomo1, C. Mattioli1, D. Greto1, G. Simontacchi1, G. Francolini1, V. Salvestrini1, I. Desideri1, L. Masi2, R. Doro2, S. Pallotta3, I. Meattini4, and L. Livi1; 1Radiation Oncology Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, Florence, Italy, 2Istituto Fiorentino di Cura e Assistenza (IFCA), CyberKnife Center, Florence, Italy, 3Medical Physic Unit, Department of Experimental and Clinical Biomedical Sciences “M. Serio”, University of Florence, Florence, Italy, 4Department of Experimental and Clinical Biomedical Sciences “M. Serio”, University of Florence, Florence, Italy
Purpose/Objective(s): Although metastatic failure remains the dominant pattern of relapse after primary treatment of pancreatic cancer (PC), isolated local recurrence (ILR) can occur in a considerable proportion of patients. The standard of care consists of systemic therapy, whereas the benefit of local consolidation remains debated. The aim of this study was to evaluate the use of SBRT for ILR from PC.
Materials/Methods: Clinical and treatment-related data from a consecutive cohort of PC patients undergoing SBRT for ILR after curative-intent therapy to the primary tumor were retrospectively collected. After SBRT, local (in-field) relapse was defined as disease progression within the 50% isodose of the SBRT plan, while distant relapse was defined as both visceral (including peritoneal carcinomatosis) and/or nodal (out-of-field) progression. Statistical analyses were performed to assess correlations between clinical variables and Local Control (LC), Progression-Free Survival (PFS), and Overall Survival (OS).
Results: Between July 2021 and February 2025, 14 patients underwent SBRT for ILR after surgery (n=12) or radiotherapy (n=2). Median follow-up was 9 (range 1–32) months. The median interval from curative treatment to ILR was 23 (range 6–61) months. Elevated CEA and/or Ca19.9 levels were observed in 7 patients. Based on target location and proximity to organs at risk, active motion management was used in 11 patients, consisting of robotic real-time tumor tracking (rRTTT) with surgical clips as surrogate fiducial markers (n=5), deep inspiration breath-hold (n=5), or abdominal compression (n=1); an ITV-based approach under free-breathing conditions was applied in the remaining patients (n=3). A total dose of 35 Gy in 5 fractions (BED=59.5 Gy10) was delivered in all cases. One-year LC, PFS, and OS rates were 69%, 31%, and 49%, respectively. Abnormal CEA levels, but not Ca19.9, correlated with poorer PFS (p=0.0061). The pattern of first failure after SBRT was distant, local, and local plus distant in 7, 3, and 1 patients, respectively. Acute toxicities included Grade 2 nausea, diarrhea, and abdominal pain in 1, 1, and 2 patients, respectively. One late Grade 3 adverse event (duodenal stenosis requiring stent placement) was observed in a previously irradiated patient.
Conclusion: SBRT delivering a dose-intensive regimen for ILR from PC after initial curative-intent therapy provides acceptable LC rates. Given the high rate of distant failure, patient selection criteria warrant further investigation. Caution is recommended in cases of prior radiotherapy. In selected cases, rRTTT using surgical clips as surrogate fiducial markers may eliminate the need for additional invasive procedures.