Gastrointestinal Cancer

PV 04 - Poster Viewing Q&A - Session 4

TU_17_2534 - Neoadjuvant Stereotactic Body Radiotherapy in Addition to Chemotherapy and Its Effect on Outcome in Resected Pancreatic Cancer

Tuesday, September 17
2:45 PM - 4:00 PM
Location: ASTRO Innovation Hub

Neoadjuvant Stereotactic Body Radiotherapy in Addition to Chemotherapy and Its Effect on Outcome in Resected Pancreatic Cancer
S. Abel1, S. Schiffman2, D. Monga3, G. Finley4, H. K. Williams4, S. Thakkar5, A. V. Kirichenko6, and R. E. Wegner1; 1Allegheny Health Network, Department of Radiation Oncology, Pittsburgh, PA, 2Allegheny Health Network, Department of Surgical Oncology, Pittsburgh, PA, 3Allegheny Health Network Division of Medical Oncology, Pittsburgh, PA, 4Allegheny Health Network, Pittsburgh, PA, 5Allegheny Health Network, Department of Gastroenterology, Pittsburgh, PA, 6Boston Consulting Group, Philadelphia, PA

Purpose/Objective(s): Pancreatic cancer remains an aggressive malignancy with poor outcomes despite aggressive treatment. To date, surgical remains the only curative treatment option. The traditional standard of care delivers adjuvant systemic therapy following resection. More recently, neoadjuvant treatment has been incorporated into the care of resectable patients, oftentimes utilizing radiotherapy in the form of stereotactic body radiotherapy (SBRT). We sought to use the National Cancer Database (NCDB) to examine trends in the use of SBRT in the neoadjuvant setting and see if there was an effect on outcome.

Materials/Methods: We queried the NCDB from 2004-2014 for patients with clinical stage 1-3 pancreatic adenocarcinoma that underwent surgical resection and were treated with neoadjuvant systemic therapy and/or SBRT based on coding within the NCDB. Odds ratios were calculated to determine predictors of SBRT use. Multivariable cox regression was used to determine predictors of overall survival. Propensity score was calculated and incorporated into the multivariable model to account for indication bias.

Results: Using the above inclusion criteria, we identified 1,872 patients receiving neoadjuvant chemotherapy, 9% of which were treated with SBRT. The majority (61%) of patients were stage 2 and 79% were treated at an academic facility. Median dose of SBRT was 35 Gy (range 24-36 Gy) in 5 fx (3-5). The median follow up was 23 months (3-134 months). Patients that were Caucasian, had higher education level, and were stage 2 or 3 were more likely to receive neoadjuvant SBRT. There was a trend towards increased utilization of SBRT with more recent year of treatment (p=0.06). On multivariable analysis higher grade, higher comorbidity score, and higher stage predicted for worse OS. Treatment at an academic facility, higher income, private insurance and SBRT were associated with improved OS. On multivariable cox regression incorporating propensity score pancreatic SBRT had better OS compared to neoadjuvant chemotherapy alone (HR: 0.77 95%CI: 0.62-0.97, p=0.02). On propensity matched Kaplan Meier analysis the median survival was 34 months compared to 24 months, in favor of SBRT (p=0.0470).

Conclusion: In this propensity matched analysis the addition of pancreatic SBRT to neoadjuvant chemotherapy resulted in improved survival, highlighting the potential importance of incorporating local therapy in the neoadjuvant setting. Prospective series directly comparing the two approaches are needed to verify the results presented here.

Author Disclosure: S. Abel: None. S. Schiffman: None. D. Monga: None. G. Finley: None. H.K. Williams: None. S. Thakkar: None. A.V. Kirichenko: None. R.E. Wegner: None.

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