Guhlich Manuel, Knaus Olga, Strauss Arne, Fischer Laura Anna, Fischer Jann, Bendrich Stephanie, Donath Sandra, Dröge Leif Hendrik, Leu Martin, Rieken Stefan, Uhlig Annemarie, Schirmer Markus Anton, Hille Andrea
Clinic of Radiotherapy and Radiation Oncology, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany.
Department of Urology, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany.
Curr Oncol. 2025 Jun 19;32(6):360. doi: 10.3390/curroncol32060360.
Combining external beam radiotherapy (EBRT) with high-dose-rate (HDR) brachytherapy (BT) enables biologically effective dose escalation in prostate cancer. However, comparative evaluation of such regimens using radiobiological modeling remains limited.
Dose regimens based on clinical practice were analyzed using α/β values of 1.5 and 3 Gy for the prostate. Ten patients with available planning CT, pelvic MRI, and ultrasound-guided BT plans were retrospectively evaluated. Physical and biological dose distributions were recalculated for various EBRT and HDR-BT combinations. Biological effective dose (BED) values were determined for the prostate and organs at risk (OARs: anterior rectal wall, bladder base, urethra). Regimens yielding the highest ΔBED between prostate and OARs were considered most favorable.
All regimens met clinical dose constraints. The most favorable ΔBED profiles for bladder and rectum were observed with HDR-BT regimens (2 × 15 Gy) combined with either 23 × 2 Gy or 15 × 2.5 Gy EBRT, independent of the assumed α/β value. EBRT-only regimens achieved superior urethral sparing, while higher HDR doses led to increased urethral exposure.
This study underscores the value of radiobiological modeling in differentiating and optimizing prostate cancer radiotherapy strategies. While the trade-offs between dose escalation and OAR sparing are clinically known, our biologically driven analysis provides a more quantitative foundation for selecting and tailoring combined EBRT/HDR-BT regimens in practice.
外照射放疗（EBRT）与高剂量率（HDR）近距离放疗（BT）相结合可提高前列腺癌的生物等效剂量。然而，使用放射生物学模型对这些方案进行比较评估仍然有限。
使用前列腺的α/β值1.5和3 Gy分析基于临床实践的剂量方案。回顾性评估了10例有可用计划CT、盆腔MRI和超声引导下BT计划的患者。重新计算了各种EBRT和HDR-BT组合的物理和生物剂量分布。确定了前列腺和危及器官（OARs：直肠前壁、膀胱底部、尿道）的生物等效剂量（BED）值。前列腺和OARs之间ΔBED最高的方案被认为是最有利的。
所有方案均符合临床剂量限制。在HDR-BT方案（2×15 Gy）与23×2 Gy或15×2.5 Gy EBRT联合使用时，观察到膀胱和直肠的ΔBED曲线最有利，与假设的α/β值无关。仅EBRT方案在保护尿道方面表现更优，而较高的HDR剂量会导致尿道受照剂量增加。
本研究强调了放射生物学模型在区分和优化前列腺癌放疗策略中的价值。虽然剂量增加与保护OARs之间的权衡在临床上是已知的，但我们基于生物学的分析为在实践中选择和定制联合EBRT/HDR-BT方案提供了更定量的基础。
