The National Cancer Data Base was queried for unresected patients who received chemotherapy for nonmetastatic pancreatic adenocarcinoma between 2004 and 2012. Four treatment groups were identified: chemotherapy alone, chemotherapy combined with external-beam radiotherapy (EBRT), chemotherapy combined with intensity-modulated radiotherapy (IMRT), and chemotherapy combined with SBRT. Propensity score models predicting the odds of receiving SBRT were created to control for potential selection bias, and patients were matched by propensity scores. The survival analysis was performed with the Kaplan-Meier method.
A total of 14,331 patients met the inclusion criteria. Chemotherapy alone was delivered to 5464 patients (38.1%); 6418 (44.8%), 322 (2.3%), and 2127 (14.8%) received chemotherapy along with EBRT, IMRT, and SBRT, respectively. The unadjusted median survival before matching was 9.9, 10.9, 12.0, and 13.9 months for patients treated with chemotherapy, EBRT, IMRT, and SBRT, respectively. In separate matched analyses, SBRT remained superior to chemotherapy alone (log-rank P < .0001) and EBRT (log-rank P = .0180). After matching, survival did not differ between patients receiving IMRT and patients receiving SBRT (log-rank P = .0492).
SBRT is associated with a significantly better outcome than chemotherapy alone or in conjunction with traditional EBRT. These results support the idea that SBRT is a promising treatment approach for patients with unresected pancreatic cancer. Cancer 2017. © 2017 American Cancer Society.