Department of Radiation Oncology, New York University School of Medicine, New York, NY 10016, USA.
Int J Radiat Oncol Biol Phys. 2012 Mar 1;82(3):e415-23. doi: 10.1016/j.ijrobp.2011.06.1950. Epub 2011 Oct 20.
We report a comparison of the dosimetry and toxicity of three-dimensional conformal radiotherapy (3D-CRT) vs. intensity-modulated radiotherapy (IMRT) among patients treated in the prone position with the same fractionation and target of the hypofractionation arm of the Canadian/Whelan trial.
An institutional review board-approved protocol identified a consecutive series of early-stage breast cancer patients treated according to the Canadian hypofractionation regimen but in the prone position. Patients underwent IMRT treatment planning and treatment if the insurance carrier approved reimbursement for IMRT; in case of refusal, a 3D-CRT plan was used. A comparison of the dosimetric and toxicity outcomes during the acute, subacute, and long-term follow-up of the two treatment groups is reported.
We included 97 consecutive patients with 100 treatment plans in this study (3 patients with bilateral breast cancer); 40 patients were treated with 3D-CRT and 57 with IMRT. IMRT significantly reduced the maximum dose (Dmax median, 109.96% for 3D-CRT vs. 107.28% for IMRT; p < 0.0001, Wilcoxon test) and improved median dose homogeneity (median, 1.15 for 3D-CRT vs. 1.05 for IMRT; p < 0.0001, Wilcoxon test) when compared with 3D-CRT. Acute toxicity consisted primarily of Grade 1 to 2 dermatitis and occurred in 92% of patients. Grade 2 dermatitis occurred in 13% of patients in the 3D-CRT group and 2% in the IMRT group. IMRT moderately decreased rates of acute pruritus (p = 0.03, chi-square test) and Grade 2 to 3 subacute hyperpigmentation (p = 0.01, Fisher exact test). With a minimum of 6 months' follow-up, the treatment was similarly well tolerated in either group, including among women with large breast volumes.
Hypofractionated breast radiotherapy is well tolerated when treating patients in the prone position, even among those with large breast volumes. Breast IMRT significantly improves dosimetry but yields only a modest but confirmed benefit in terms of toxicities. If a concurrent boost to the tumor bed is not required, a conformal 3D-CRT approach can adequately deliver prone whole-breast hypofractionation radiotherapy.
我们报告了在加拿大/惠兰试验的短程放疗亚组中，采用相同分割和靶区，对接受俯卧位治疗的患者进行三维适形放疗（3D-CRT）与调强放疗（IMRT）的剂量学和毒性比较。
机构审查委员会批准的方案确定了一系列连续的早期乳腺癌患者，他们根据加拿大的短程放疗方案进行治疗，但采用俯卧位。如果保险承保人批准 IMRT 报销，则对患者进行 IMRT 治疗计划和治疗；如果拒绝，则使用 3D-CRT 计划。报告了两组患者在急性、亚急性和长期随访期间的剂量学和毒性结果的比较。
本研究共纳入 97 例连续患者，共 100 例治疗计划（3 例双侧乳腺癌患者）；40 例患者接受 3D-CRT 治疗，57 例患者接受 IMRT 治疗。与 3D-CRT 相比，IMRT 显著降低了最大剂量（Dmax 中位数，3D-CRT 为 109.96%，IMRT 为 107.28%；p < 0.0001，Wilcoxon 检验）和改善了中位剂量均匀性（中位数，3D-CRT 为 1.15，IMRT 为 1.05；p < 0.0001，Wilcoxon 检验）。急性毒性主要为 1 级至 2 级皮炎，发生在 92%的患者中。3D-CRT 组中 13%的患者发生 2 级皮炎，IMRT 组中 2%的患者发生 2 级皮炎。IMRT 适度降低了急性瘙痒的发生率（p = 0.03，卡方检验）和 2 级至 3 级亚急性色素沉着过度的发生率（p = 0.01，Fisher 确切检验）。随访至少 6 个月后，两组患者的治疗均具有良好的耐受性，包括乳房体积较大的患者。
即使在乳房体积较大的患者中，俯卧位治疗也能很好地耐受短程放疗。乳房 IMRT 显著改善了剂量学，但在毒性方面仅产生适度但确认的获益。如果不需要对肿瘤床进行同期加量，那么采用适形 3D-CRT 方法就可以充分地给予俯卧位全乳短程放疗。
