Isotoxic High-Dose Stereotactic Body Radiotherapy (iHD-SBRT) Versus Conventional Chemoradiotherapy for Localized Pancreatic Cancer: A Single Cancer Center Evaluation

SIMPLE SUMMARY: Pancreatic ductal adenocarcinoma (PDAC) is an aggressive tumour associated with poor prognosis. The only potentially curative treatment is an oncological surgical resection. To increase the probability of resection, the use of neoadjuvant treatment is explored and can include chemoradiotherapy (CRT) or stereotactic body radiotherapy (SBRT). Given the lack of direct comparison between the two modalities, we retrospectively compared the clinical outcomes of patients treated for localized PDAC by isotoxic high dose SBRT (iHD-SBRT) with those of patients treated with conventional CRT in the same cancer center. The oncological outcomes showed that iHD-SBRT seems to be a promising option and may offer an improvement in overall survival in comparison to conventional CRT for localized PDAC. Further investigations are required to identify the exact role of SBRT and the optimal therapeutic neoadjuvant sequence. ABSTRACT: Given the lack of direct comparative evidence, we aimed to compare the oncological outcomes of localized pancreatic ductal adenocarcinoma (PDAC) treated in the same tertiary cancer center with isotoxic high-dose stereotactic body radiotherapy (iHD-SBRT) or conventional chemoradiotherapy (CRT). Biopsy-proven borderline/locally advanced patients treated with iHD-SBRT (35 Gy in 5 fractions with a simultaneous integrated boost up to 53 Gy) or CRT (45–60 Gy in 25–30 fractions) were retrospectively included from January 2006 to January 2021. The median overall survival (mOS) was evaluated trough uni- and multivariate analyses. The progression free survival (PFS) and the 1-year local control (1-yLC) were also reported. Eighty-two patients were included. The median follow-up was 19.7 months. The mOS was in favour of the iHD-SBRT group (22.5 vs. 15.9 months, p < 0.001), including after multivariate analysis (HR 0.39 [CI95% 0.18–0.83], p = 0.014). The median PFS and the 1-yLC were also significantly better for iHD-SBRT (median PFS: 16.7 vs. 11.5 months, p = 0.011; 1-yLC: 75.8 vs. 39.3%, p = 0.004). In conclusion, iHD-SBRT is a promising RT option and may offer an improvement in OS in comparison to CRT for localized PDAC. Further validation is required to confirm the exact role of iHD-SBRT and the optimal therapeutic sequence for the treatment of localized PDAC.