3388 - Escalated-Dose Ablative Radiation Therapy for Oligometastatic Pancreatic Cancer: A Single-Institution Experience
Presenter(s)
M. M. Basree1, N. J. Hurst Jr2, M. A. Patel3, A. Shepard4, M. Lubner5, S. M. Ronnekleiv-Kelly6, J. D. Kratz3, N. N. Zafar6, N. Loconte3, S. Lubner3, C. Glide-Hurst4, N. Uboha3, and M. F. Bassetti1; 1Department of Human Oncology, University of Wisconsin Hospitals and Clinics, Madison, WI, 2William S. Middleton Memorial Veterans Hospital, Madison, WI, 3Department of Medical Oncology, University of Wisconsin Carbone Cancer Center, Madison, WI, 4Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, WI, 5Department of Radiology, University of Wisconsin Hospitals & Clinics, Madison, WI, 6Department of Surgical Oncology, University of Wisconsin Hospitals and Clinics, Madison, WI
Purpose/Objective(s):
Standard-of-care for patients with metastatic pancreatic cancer is chemotherapy. At our institution, escalated-dose ablative radiation therapy (RT) is used for select oligometastatic pancreatic cancer patients to improve local control and/or to delay systemic therapy. This study presents our clinical outcomes utilizing this treatment strategy.Materials/Methods:
A retrospective review of 22 patients treated with RT between 10/2015 and 11/2023 was completed. Patients were referred to Radiation Oncology for oligometastatic disease progression (n=16; 72.7%) or for disease consolidation (n=6; 27.3%). Kaplan-Meier (KM) method was used to estimate survival outcomes, and Spearman’s correlation was used to assess associations between clinical variables and time-to-event outcomes. Statistical software was used for statistical analysis.Results:
The majority of patients were male (n=14; 63.6%), ECOG of 0-1 (n=21; 95.5%), and initially had localized, operable disease (n=17; 77.3%), with a median time from surgery to metastatic progression of 15.6 months (range, 1.4–57.9). The most common metastatic sites were lung (45.5%) and liver (40.9%), with a median of 1 metastatic site per patient (range, 1–9). RT was delivered to a median dose of 60 Gy (range, 40–67.5) in 5 fractions (range, 5–15). Median chemotherapy-free interval (CFI) from end of RT to re-initiation of chemotherapy was 7.3 months (range, 1.8–59.2), with 1- and 2-year CFI rates of 50.0% and 22.7%, respectively. Seven patients completed at least 1 additional course of RT (n=7; 31.8%) to new progressive sites instead of systemic therapy. With a median follow-up of 15.7 months (range, 3.2–93.7), KM estimated median OS from SBRT was 21.9 months (95% CI, 8.4–35.3), with estimated 1- and 2-year OS at 66.2% and 48.9%, respectively. Median DFS was 3.5 months (95% CI, 1.3–5.6), with estimated 1-year DFS of 18.2%. Local failure in the treated metastatic lesions was rare at 4.5%. Longer CFI and increased time from surgery to first distant recurrence were significantly correlated with improved OS and DFS (p<0.05).Conclusion:
Escalated-dose ablative radiation therapy provides select oligometastatic pancreatic patients with good chemotherapy-free interval and local control. Certain cases of new disease progression after initial RT could be salvaged with additional RT, further extending the CFI. These findings suggest that escalated-dose ablative radiation therapy may be utilized as part of a multimodal treatment approach for patients with oligometastatic pancreatic cancer and warrants further investigation.