PURPOSE: The role of preoperative stereotactic body radiation therapy (SBRT) in pancreatic cancer is controversial, and questions regarding the optimal dose and radiation treatment field remain. To better inform future investigations of SBRT dose and radiation fields, we evaluated the patterns of failure in patients with borderline resectable/locally advanced pancreatic cancer (BR/LAPC) after preoperative chemotherapy and SBRT in patients who underwent surgical resection. METHODS AND MATERIALS: We performed a single-institution retrospective review of consecutive patients treated from September 2017 to January 2022 with BR/LAPC. Patients who underwent preoperative chemotherapy and SBRT followed by surgical resection were reviewed. SBRT was delivered to a dose of 33 Gy in 5 fractions. Kaplan-Meier overall survival and progression-free survival estimates were calculated. RESULTS: In total, 18 patients (12 BRPC, 6 LAPC) were included. Median age was 69 years (range 41-84 years). Median follow-up was 30 months (range 13-59 months). Seventeen patients (94%) had a R0 resection and 13 (72%) underwent vascular reconstruction. Median overall survival and progression-free survival was 42 months (range 13-59 months) and 23 months (range 1-45 months), respectively. In total, 61% (11/18) patients experienced progression at any point during follow-up. Of the patients who experienced recurrence, 27% (3/11) experienced local progression as component of their first recurrence, whereas 100% (11/11) experienced distant progression as a component of their first recurrence. When examining all recurrences that occurred at any point in follow-up, 28% (5/18) of patients experienced local or locoregional recurrence and 61% (11/18) experienced distant progression. CONCLUSIONS: Local control and margin negative resection rates were excellent with preoperative chemotherapy and nondose-escalated SBRT in surgically resected patients with BR/LAPC. Distant recurrence was the predominant site of failure with lower incidences of isolated locoregional recurrences. Additional research is needed to determine the ideal treatment volume and patients who may benefit from dose escalation.

Most adult carcinomas develop from noninvasive precursor lesions, a progression that is supported by genetic analysis. However, the evolutionary and genetic relationships among co-existing lesions are unclear. Here we analysed the somatic variants of pancreatic cancers and precursor lesions sampled from distinct regions of the same pancreas. After inferring evolutionary relationships, we found that the ancestral cell had initiated and clonally expanded to form one or more lesions, and that subsequent driver gene mutations eventually led to invasive pancreatic cancer. We estimate that this multi-step progression generally spans many years. These new data reframe the step-wise progression model of pancreatic cancer by illustrating that independent, high-grade pancreatic precursor lesions observed in a single pancreas often represent a single neoplasm that has colonized the ductal system, accumulating spatial and genetic divergence over time.