Yang Daniel X, Verma Vivek, An Yi, Yu James B, Sprenkle Preston C, Leapman Michael S, Park Henry S
Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut.
Department of Radiation Oncology, Allegheny General Hospital, Pittsburgh, Pennsylvania.
Adv Radiat Oncol. 2020 Sep 15;5(6):1225-1231. doi: 10.1016/j.adro.2020.08.015. eCollection 2020 Nov-Dec.
Management options for localized prostate cancer include definitive radiation therapy (RT) or radical prostatectomy, with a subset of surgical patients requiring adjuvant or salvage RT after prostatectomy. The use of a peri-rectal hydrogel spacer in patients receiving definitive RT has been shown to reduce rectal doses and toxicity. However, in the postprostatectomy setting, a hydrogel spacer cannot be routinely placed. Therefore, we sought to compare rectal dosimetry between definitive RT with a hydrogel spacer versus postoperative RT.
We identified patients with prostate cancer who underwent conventionally fractionated RT. Rectal dosimetry was evaluated between 2 groups: definitive RT with a hydrogel spacer (79.2 Gy, group 1) and postoperative RT (70.2 Gy, group 2). Rectal dosimetry values were tabulated and compared using Mann-Whitney test. We implemented a Bonferroni correction to account for multiple comparisons (threshold < .005). Linear regression analysis evaluated predictors of candidate rectal dose-volume parameters.
We identified 51 patients treated during years 2017 to 2018; 16 (31%) and 35 (69%) patients were included in groups 1 and 2, respectively. The rectal volume receiving ≥65 Gy (V65) was significantly lower in group 1 (median, 2.1%; interquartile range, 0.9%-3.1%) than in group 2 (10.7%, 6.6%-14.5%) ( < .001). Use of a hydrogel spacer in the definitive setting was independently associated with lower V65 ( < .001). Similar results were found for V60, V55, V50, and V45 ( < .005 for all).
Rectal dosimetry is more favorable for definitive RT (79.2 Gy) with a hydrogel spacer compared with postoperative RT (70.2 or 66.6 Gy). This may inform shared decision-making regarding primary management of prostate cancer, especially among patients at high risk of needing postoperative RT after prostatectomy.
局限性前列腺癌的治疗选择包括根治性放射治疗（RT）或根治性前列腺切除术，部分手术患者在前列腺切除术后需要辅助或挽救性RT。在接受根治性RT的患者中使用直肠周围水凝胶间隔物已被证明可降低直肠剂量和毒性。然而，在前列腺切除术后的情况下，水凝胶间隔物不能常规放置。因此，我们试图比较使用水凝胶间隔物的根治性RT与术后RT之间的直肠剂量测定。
我们确定了接受常规分割RT的前列腺癌患者。在两组之间评估直肠剂量测定：使用水凝胶间隔物的根治性RT（79.2 Gy，第1组）和术后RT（70.2 Gy，第2组）。将直肠剂量测定值制成表格并使用Mann-Whitney检验进行比较。我们采用Bonferroni校正来考虑多重比较（阈值<0.005）。线性回归分析评估候选直肠剂量-体积参数的预测因素。
我们确定了2017年至2018年期间接受治疗的51例患者；第1组和第2组分别纳入16例（31%）和35例（69%）患者。第1组中接受≥65 Gy（V65）的直肠体积显著低于第2组（中位数，2.1%；四分位间距，0.9%-3.1%）（10.7%，6.6%-14.5%）（<0.001）。在根治性治疗中使用水凝胶间隔物与较低的V65独立相关（<0.001）。V60、V55、V50和V45也得到了类似的结果（所有均<0.005）。
与术后RT（70.2或66.6 Gy）相比，使用水凝胶间隔物的根治性RT（79.2 Gy）的直肠剂量测定更有利。这可能为前列腺癌的初始治疗决策提供参考，尤其是在前列腺切除术后需要术后RT风险较高的患者中。
