Session Item

Stereotactic body radiotherapy (SBRT) has emerged as a promising new modality for locally advanced pancreatic cancer (LAPC). The current study evaluated the efficacy and toxicity of SBRT (planned 50 Gray in 5 fractions in 10 days) in patients with LAPC (NCT03648632).

In this prospective Danish phase II study, participants were recruited from Departments of Oncology in Denmark. Eligible patients had locally advanced histologically or cytological proven adenocarcinoma of the pancreas and were medically operable. All patients were aged ≥18 years with a performance status of 0-1, with adequate organ function, and had received prior combination chemotherapy (FOLFIRINOX, Gemcitabine/Abraxane, Gemcitabine/Capecitabine or Gemcitabine/S1) for at least 2 months with no sign of progressive disease.

Patients were screened, staged and evaluated at the local multi-disciplinary team conference before inclusion in the protocol. A delay of at least two weeks between systemic chemotherapy and SBRT was recommended. The first 6 included patients received intensity-modulated radiotherapy initially on a standard accelerator. Since July 2019, the treatment was given on the MR-linac, where the treatment plan was adapted daily, adjusted for the anatomy of the day (tumor as well as organs at risk (OAR)), to maximize the dose delivered to the tumor and minimize the dose to OAR.

The primary endpoint was resection rate for patients starting SBRT. Secondary endpoints were 1-year survival for patients starting SBRT, PFS, OS (time from inclusion to death), adverse events and surgical complications. The cutoff date was 01.10.2021. 

Twenty-seven patients were enrolled between August 2018 and September 2021. The median age was 68 years (range 39-80), and 70% (n=19) were females. The majority of patients (n=20, 74%) had T4-disease. All 27 patients completed the planned SBRT, and 25 patients received 50 Gray over 5 fractions. Due to OAR and tumor size, 2 patients received 60 Gray over 8 fractions. Twenty-one patients were treated on the MR-Linac. Five patients (19%) have been resected, 2 patients declined surgical exploration. Sixteen patients are still alive. The median overall survival was 19.1 months (95% CI 10.7-21.2).

Overall, the treatment was well tolerated with nausea and abdominal pain as the most common adverse events. Two patients had severe adverse events (1 patient had duodenal perforation after treatment on the standard accelerator, 1 patient experienced upper GI bleeding due to progression of the tumor). 

MR guided adaptive SBRT in patients with locally advanced or borderline pancreatic cancer has shown promising efficacy with acceptable toxicity. A national randomized trial, investigating whether adding SBRT in the treatment course will increase the chance of resection, is being planned.