Biologically effective doses for α/β = 10 (BED10) of

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Background The optimal biologically effective dose (BED 10 ) for stereotactic body radiation therapy (SBRT) in pancreatic cancer remains debated. This study evaluated whether BED 10 ≥80 Gy improves outcomes compared with <80 Gy in a heterogeneous patient population. Methods 46 patients with pancreatic cancer treated with SBRT (May 2021–December 2023) were retrospectively analyzed. Overall survival (OS), progression-free survival (PFS), and local control (LC) were estimated using the Kaplan–Meier method with log-rank testing. Multivariable Cox regression was performed adjusting for disease stage, chemotherapy, tumor size, dose group, and fiducial marker status, with exploratory interaction and subgroup analyses. Results Among the 46 patients (10 Stage I/II, 17 locally advanced, 19 metastatic), median OS was 13.0 months (95% CI: 9.9–16.1), with 1-year OS of 51.2% (<80 Gy) vs. 53.3% (≥80 Gy) (log-rank p=0.442). Multivariable analysis showed no significant dose effect (HR 1.472, p=0.342). Independent prognostic factors were disease stage (HR 0.274, p=0.006), tumor size (HR 0.399, p=0.026), chemotherapy (HR 0.410, p=0.029), and absence of fiducial markers (HR 4.224, p=0.006). No significant dose × stage (p=0.373) or dose × chemotherapy (p=0.104) interactions were observed. In 27 patients with evaluable imaging, LC was 92.6% and median PFS was 8.0 vs. 10.0 months (log-rank p=0.605). Conclusion In this single-center retrospective analysis, BED 10 ≥80 Gy was not associated with a statistically significant survival benefit compared with <80 Gy. Independent prognostic factors included disease stage, tumor size, and chemotherapy. The favorable local control and absence of grade ≥3 toxicity suggest that CyberKnife-based SBRT is effective and safe across the studied dose range. However, the heterogeneous study population (41% metastatic) and narrow dose distribution limit definitive conclusions regarding dose-response. Larger prospective studies with homogeneous cohorts are needed to determine whether dose escalation beyond 80 Gy confers meaningful clinical benefit, particularly in patients with locally advanced disease.