(S016) The Impact of Stereotactic Body Radiation Therapy on Overall Survival in Patients With Locally Advanced Pancreatic Cancer

Lauren M. Rosati, BS, Avani S. Rao, MD, Amy Hacker-Prietz, MS, PAC, Matthew J. Weiss, MD, Christopher L. Wolfgang, MD, PhD, Timothy M. Pawlik, MD, MPH, PhD, John L. Cameron, MD, Martin A. Makary, MD, MPH, Ana DeJesus Acosta, MD, Dung T. Le, MD, Lei Zheng, MD, PhD, Daniel A. Laheru, MD, Susannah G. Ellsworth, MD, Joseph M. Herman, MD, MSc; Johns Hopkins University School of Medicine

BACKGROUND: The efficacy of stereotactic body radiation therapy (SBRT) in locally advanced pancreatic cancer (LAPC) is not fully understood. We retrospectively analyzed the role of chemotherapy and SBRT on overall survival (OS) in patients with LAPC.

METHODS: From July 2010 to April 2015, a total of 136 patients with LAPC were treated with definitive SBRT to a median dose of 33 Gy (range: 25–33 Gy) at our institution. Eighteen patients were excluded from the analysis due to treatment with palliative intent or lack of follow-up. Ninety-three percent of patients received induction chemotherapy prior to SBRT. Kaplan-Meier survival estimates were calculated.

RESULTS: Of the 118 analyzable patients, 52% were male, 83% were Caucasian, and 58% had head lesions. Median duration of induction chemotherapy was 2.96 months. Eighty-four (71%) patients received multiagent chemotherapy, and 49 (42%) received 5-fluorouracil (5-FU)-based chemotherapy. Thirty-three (28%) patients went to surgery, with margin- and node-negative resection rates of 94% and 85%, respectively.

Median OS from diagnosis and from end of SBRT was 19.5 and 14.5 months, respectively. 5-FU chemotherapy was associated with superior survival in comparison with gemcitabine-based chemotherapy (27.7 mo vs 16.7 mo; P =.004). Patients receiving multiagent chemotherapy survived a median of 23.5 months vs 15.7 months in those receiving single-agent chemotherapy (P =.011). Chemo­therapy duration ≥ 4 months was associated with superior OS (34.8 mo vs 15.8 mo; P < .0001). Patients who went to surgery survived a median of 34.7 months vs 17.0 months in those who did not (P < .0001). Patients who achieved a margin-negative resection survived significantly longer (34.8 mo vs 15.7 mo; P < .0001), whereas patients who underwent node-negative resection had inferior survival (29.8 mo vs 34.8 mo; P < .0001).

CONCLUSIONS: SBRT appears to have a survival benefit in patients with LAPC, especially after the delivery of maximal multiagent chemotherapy. SBRT may play a role in tumor downstaging and allow patients with LAPC to undergo surgery.

Proceedings of the 98^th Annual Meeting of the American Radium Society - americanradiumsociety.org