Clinical outcomes Clinical data were gathered by retrospective chart review using electronic patient records. Date of progression was defined as the date of first

follow-up cross-sectional imaging study showing evidence of distant metastases or local progression as determined by an attending radiologist. Survival was measured from the date of the first fraction of SBRT until date of death or censored at the date of last follow-up if no date of death was available. Toxicity was evaluated using the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0. Statistics Patient demographic, clinicopathologic, Inhibitors,research,lifescience,medical and PI-103 research buy treatment characteristics were summarized using descriptive statistics. Patient characteristics were compared among different patient subgroups using the Mann-Whitney U test for comparison of medians and the Pearson chi-square test for comparison of proportions. Survival data were analyzed using Kaplan-Meier statistics

and compared between subgroups using the log-rank test. A two-sided alpha level of ≤0.05 was considered Inhibitors,research,lifescience,medical significant in all cases. Statistical analyses were performed with SPSS (IBM, Armonk, NY). Results Patients Eighteen patients were identified. Complete demographic, baseline, and treatment characteristics are summarized Inhibitors,research,lifescience,medical in Table 1. Fifteen patients received neoadjuvant or adjuvant CRT in association with surgical resection, while 3 received definitive Inhibitors,research,lifescience,medical CRT for locally advanced disease. Median CRT dose was 50.4 Gy (IQR, 45.0-50.4 Gy) in 28 fractions with median daily fraction size of 1.8 Gy (IQR, 1.8-1.8 Gy). Seventeen of 18 patients (94%) received chemotherapy concurrently with radiotherapy.

All patients subsequently received gemcitabine-based maintenance chemotherapy, but eventually developed isolated local disease recurrence/progression without evidence of distant metastasis. Median time to local recurrence/progression following surgery or definitive CRT Inhibitors,research,lifescience,medical was 13.1 months (IQR, 7.8-17.5 months). Mean diameter of locally recurrent/progressive disease at SBRT was 2.7 cm (SD, 0.9 cm). All patients others underwent re-irradiation of the pancreatic bed with SBRT administered over 5 consecutive daily fractions. Sixteen of 18 patients (89%) received a total dose of 25 Gy (5 Gy ×5), while 1 patient received 20 Gy (4 Gy ×5) and 1 patient received 27 Gy (5.5 Gy ×5). Five patients (28%) received additional chemotherapy following SBRT. Table 1 Demographic, baseline disease, and treatment characteristics Efficacy Median follow-up was 34.3 months (range, 6.4-61.6 months) and median interval from local recurrence/progression to SBRT was 2.4 months (IQR, 1.8-5.1 months). Median survival measured from the time of radiographically documented local recurrence/progression was 12.0 months (95% CI, 9.9-14.0 months). Median survival measured from SBRT was 8.8 months (95% CI, 1.2-16.4 months) (Figure 1A).