Utilization of Advanced Radiation Techniques in Neuroendocrine Carcinoma of the Pancreas

Abstract

<h3>Purpose/Objective(s)</h3> Pancreatic neuroendocrine neoplasms (PNEN) are a rare disease entity with a wide spectrum of clinical behavior. To date, surgery remains the standard of care curative option for patients with early stage PNENs. However, a subset of patients will be ineligible for surgery requiring alternative treatment approaches such as radiotherapy. We thus used the National Cancer Database to examine trends in radiation use for PNEN, focusing specifically on different radiation techniques. <h3>Materials/Methods</h3> We queried the NCDB from 2004-2015 for patients with PNEN that were treated with external beam radiation techniques including 3D conformal radiotherapy (3D-CRT), intensity modulated RT (IMRT), and stereotactic body radiation therapy (SBRT). Baseline characteristics were tabulated. Multivariable logistic regression was used to identify predictors of SBRT and IMRT use. Multivariable Cox regression was used to identify predictors of survival. Kaplan Meier curves were generated to estimate survival. <h3>Results</h3> Using the above criteria we identified 185 patients, of which 18% received SBRT and 25% received IMRT. The median age was 61 years (31-90) and the majority of patients (27%) had stage II disease. The median IMRT dose was 45 Gy (IQR: 41.6-50.4 Gy) in 25 fractions and the median SBRT dose was 30 Gy (25.5-39.8 Gy) in 5 fractions. Predictors of SBRT use included lack of chemotherapy and earlier T stage. Predictors of IMRT use were conventional fractionation and more recent treatment year. The median follow up was 21.9 months (IQR: 10.7-38.6). On Cox regression, predictors of worse survival were older age, higher comorbidity score, higher grade, and higher T stage. Kaplan Meier analysis revealed median survival of 27 months and 40 months for CFRT and SBRT, respectively (p=0.17). <h3>Conclusion</h3> This analysis shows a small but steady increase in the use of advanced radiation techniques for localized PNEN. SBRT appears to be a reasonable option in appropriately selected candidates.