Gurewitz Jason, Oh Cheongeun, Woo Sungmin, Kim Jiyu, Bruzzese Adam, Chen Ting, Wang Hesheng, Byun David, Zelefsky Michael J
Department of Radiation Oncology, NYU Grossman School of Medicine, New York, NY, USA.
Department of Population Health, NYU Grossman School of Medicine, USA.
Clin Transl Radiat Oncol. 2025 Jun 28;54:101007. doi: 10.1016/j.ctro.2025.101007. eCollection 2025 Sep.
We evaluated prostate volume changes during stereotactic body radiation therapy (SBRT) using serial MRI, identifying variables associated with prostatic swelling and their correlation with acute toxicity.
Fifty-two patients with localized prostate cancer, androgen deprivation therapy naive, underwent SBRT to 40 Gy in five fractions on an MRI-Linear Accelerator with dominant intraprostatic lesion boosts to 45 Gy when present. Whole prostate (WP) and transition zone (TZ) measurements were assessed on the pre-treatment T2 MRI obtained for daily adaptation. Volumes were calculated using the ellipsoid formula. Non-transition zone (nonTZ) measures = WP values - TZ values. Transition zone index (TZI) = TZ volume/WP volume. Acute toxicity and International Prostate Symptom Scores (IPSS) were recorded.
Prostate volume increased significantly over the first four fractions, peaking at fraction 4 with mean percent and absolute changes of 21 % and 7.8 cc, respectively. Standardized TZ measures were strongly associated with WP volume (β per SD 10.60-12.78; all p < 0.001), whereas the only nonTZ dimension weakly associated was anteroposterior (β per SD 1.78). Each standard deviation increase in baseline TZ parameters doubled to tripled the odds of significant swelling (≥10 cc) (all p ≤ 0.011). The interaction of baseline TZI with later fractions was significantly associated with swelling (fraction 4: β = 12.06, p = 0.020; fraction 5: β = 10.96, p = 0.036), but not baseline TZI alone. Neither Grade 2+ genitourinary toxicity nor IPSS changes were associated with prostate measures or TZI.
Prostate volume significantly increases during SBRT, primarily corresponding with TZ volumetric changes. Baseline TZ measurements most strongly predict high-volume swelling. Acute toxicity was not associated with volumetric change.
我们使用系列MRI评估了立体定向体部放射治疗（SBRT）期间前列腺体积的变化，确定与前列腺肿胀相关的变量及其与急性毒性的相关性。
52例未经雄激素剥夺治疗的局限性前列腺癌患者在MRI直线加速器上接受SBRT，分5次给予40 Gy，若存在前列腺内主要病灶则增加剂量至45 Gy。在为每日适应性调整而获取的治疗前T2 MRI上评估整个前列腺（WP）和移行区（TZ）的测量值。使用椭球体公式计算体积。非移行区（nonTZ）测量值=WP值-TZ值。移行区指数（TZI）=TZ体积/WP体积。记录急性毒性和国际前列腺症状评分（IPSS）。
在前四个分次中前列腺体积显著增加，在第4分次时达到峰值，平均百分比变化和绝对变化分别为21%和7.8 cc。标准化的TZ测量值与WP体积密切相关（每标准差β为10.60 - 12.78；所有p<0.001），而唯一弱相关的nonTZ维度是前后径（每标准差β为1.78）。基线TZ参数每增加一个标准差，显著肿胀（≥10 cc）的几率增加一倍至两倍（所有p≤0.011）。基线TZI与后续分次的相互作用与肿胀显著相关（第4分次：β = 12.06，p = 0.020；第5分次：β = 10.96，p = 0.036），但单独的基线TZI则不然。2级及以上泌尿生殖系统毒性和IPSS变化均与前列腺测量值或TZI无关。
SBRT期间前列腺体积显著增加，主要与TZ体积变化相对应。基线TZ测量最能强烈预测大体积肿胀。急性毒性与体积变化无关。
