Long-term outcomes of induction chemotherapy and neoadjuvant stereotactic body radiotherapy for borderline resectable and locally advanced pancreatic adenocarcinoma

360 Background: Limited data is available for neoadjuvant treatment of borderline resectable (BRPC) and locally advanced (LAPC) pancreatic cancer. We update our institutional outcomes with a neoadjuvant chemotherapy and stereotactic body radiotherapy (SBRT) approach. Methods: We performed an IRB-approved analysis of all BRPC and LAPC patients treated with our departmental treatment protocol. After staging, medically fit patients underwent chemotherapy for 2-3 months, with regimen at the discretion of the treating medical oncologist (FOLFIRINOX, GTX, gem/abraxane, or gemcitabine alone). Patients then received SBRT delivered in 5 consecutive daily fractions with median radiation doses of 30 Gy to tumor and 40 Gy dose painted to tumor-vessel interfaces. This was followed by restaging imaging for possible resection. Overall survival (OS), event free survival (EFS), and locoregional control (LRC) rates were estimated and compared by Kaplan-Meier and log-rank methods. Results: We identified 159 patients, 110 BRPC and 49 LAPC, with 14.0 months median overall follow-up. The resection and margin negative (R0) rate for BRPC patients who completed neoadjuvant therapy was 50.9% and 96.4%, respectively. Estimated median OS was 14.4 months for BRPC patients and 11.3 months for LAPC patients (p=0.402). Median OS was 34.2 months for surgically resected patients vs 14.0 months for unresected patients (p