A. A. Vera1, A. H. Zureikat2, M. Lotze3, A. Paniccia2, K. K. Lee2, J. Shogan4, B. Elgohari5, M. K. Abdelhakiem4, M. A. Mohammed6, J. Y. Zhang7, S. A. Burton4, and S. G. Ellsworth4; 1UPMC, Department of Radiation Oncology, Pittsburgh, PA, 2Department of Surgery, University of Pittsburgh, Pittsburgh, PA, 3University of Pittsburgh Hillman Cancer Center, Pittsburgh, PA, 4Department of Radiation Oncology, UPMC Hillman Cancer Center, Pittsburgh, PA, 5MD Anderson Cancer Center, Houston, PA, 6American university of Beirut Medial center, Beirut, Lebanon, 7UPMC, Department of Hematology/Oncology, Pittsburgh, PA
Purpose/Objective(s): Multiple early-phase studies have evaluated stereotactic body radiation (SBRT) for locally advanced pancreatic cancer (LAPC). However, long-term follow up data is lacking. We present results from a single institution cohort of LAPC patients treated with SBRT and followed since 2007. Materials/
Methods: 198 LAPC patients were identified from a prospectively maintained database. All patients underwent multidisciplinary assessment including evaluation by a surgical oncologist specialized in PDAC. Median age was 70 years (36-91); 99 patients (49.7%) were women. Median baseline KPS was 80% (60-100). SBRT was delivered using a linear accelerator and respiratory motion management. The most common fractionation was 12 Gy x 3 (n=89, 44.7%), followed by 6-8 Gy x 5 (n=81, 40.7%). 26 patients (13.1%) received single fraction SBRT (18-22 Gy). Most patients (n=171, 83.8%) received neoadjuvant chemotherapy, most often gemcitabine/nab-paclitaxel (n=62, 30.4%) or FOLFIRINOX (n=40, 19.6%). 4 patients underwent resection. Results: As of March 1, 2024, 180/198 patients had died; median follow up was 20.4 mos. Median overall survival (OS) from diagnosis was (95%CI 7.8-10.4). Three patients (1.5%) survived >5 years after diagnosis with 1 patient alive at 11 years. Median OS from diagnosis was 10.6 mos among patients treated in 2005-09, 13.8 mos in 2010-14, 16.1 mos in 2015-19, and 18.1 mos in 2020-23 (p<0.001). Median OS from end-SBRT for the same time periods was 8.0, 8.2, 9.9, and 10.5 mos, respectively (p=0.004). . Median local progression free survival (LPFS) was 7.9 mos after SBRT (95%CI 6.7-9.0). Cox regression showed that lack of chemotherapy before SBRT, CA19-9 increase after SBRT, and radiation-induced lymphopenia were all correlated with worse LPFS. In patients who did not receive chemotherapy (n=33) LPFS was 6.1 mos vs 8.5 mos among those who did (n=152), p = 0.004. 7. In patients with grade 0-1 (n=66) vs grade 2-4 lymphopenia (n=39), LPFS was 9.9 vs 6.8 months, p = 0.04. Grade 3 or greater gastrointestinal (GI) toxicity occurred in 20 patients (10.1%); 13 patients (6.5%) had upper GI bleeding, 2 (1.0%) had pseudoaneurysm, and 5 (2.5%) had radiation. Conclusion: In this cohort of patients, SBRT was well tolerated with =grade 3 GI toxicity rates comparable to other reported series. Improvements in OS were observed over time, which may be due to the use of more active chemotherapy regimens and advancements in RT technique. CA19-9 dynamics are correlated with response to SBRT and OS in LAPC.
