Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Ontario, Canada.
Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Ontario, Canada.
Int J Radiat Oncol Biol Phys. 2022 Feb 1;112(2):342-350. doi: 10.1016/j.ijrobp.2021.09.003. Epub 2021 Sep 17.
Multileaf collimator (MLC) linear accelerator (Linac)-based hypofractionated stereotactic radiation therapy (HSRT) is increasingly used not only for large brain metastases or those adjacent to critical structures but also for those metastases that would otherwise be considered for single-fraction radiosurgery (SRS). However, data on outcomes in general are limited, and there is a lack of understanding regarding optimal dosing. Our aim was to report mature image-based outcomes for MLC-Linac HSRT with a focus on clinical and dosimetric factors associated with local failure (LF).
A total of 220 patients with 334 brain metastases treated with HSRT were identified. All patients were treated using a 5-fraction daily regimen and were followed with clinical evaluation and volumetric magnetic resonance imaging every 2 to 3 months. Overall survival and progression-free survival were calculated using the Kaplan-Meier method, with LF determined using Fine and Gray's competing risk method. Predictive factors were identified using Cox regression multivariate analysis.
Median follow-up was 10.8 months. Median size of treated metastasis was 1.9 cm; 60% of metastases were <2 cm in size. The median total dose was 30 Gy in 5 fractions; 36% of the cohort received <30 Gy. The median time to LF and 12-month cumulative incidence of LF was 8.5 months and 23.8%, respectively. Median time to death and 12-month overall survival rates were 11.8 months and 48.2%, respectively. Fifty-two metastases (15.6%) had an adverse radiation effect, of which 32 (9.5%) were symptomatic necrosis. Multivariable analysis identified worse LF in patients who received a total dose of <30 Gy (hazard ratio, 1.62; P = .03), with LF at 6 and 12 months of 13% and 33% for patients treated with <30 Gy versus 5% and 19% for patients treated with >30 Gy. Exploratory analysis demonstrated a dose-response effect observed in all histologic types, including among breast cancer subtypes.
Optimal local control is achieved with HSRT of ≥30 Gy in 5 daily fractions, independent of tumor volume and histology, with an acceptable risk of radiation necrosis.
多叶准直器（MLC）直线加速器（Linac）为基础的大分割立体定向放射治疗（HSRT）不仅越来越多地用于大的脑转移瘤或邻近关键结构的转移瘤，也越来越多地用于那些否则被认为是单次分割放射外科（SRS）的转移瘤。然而，一般来说，关于结果的数据是有限的，而且对于最佳剂量的理解也很缺乏。我们的目的是报告基于 MLC-Linac HSRT 的成熟图像结果，重点是与局部失败（LF）相关的临床和剂量学因素。
共确定了 220 名接受 HSRT 治疗的 334 例脑转移瘤患者。所有患者均采用 5 次分割每日治疗方案，并通过临床评估和每 2-3 个月进行容积磁共振成像进行随访。使用 Kaplan-Meier 法计算总生存率和无进展生存率，使用 Fine 和 Gray 的竞争风险法确定 LF。使用 Cox 回归多变量分析确定预测因素。
中位随访时间为 10.8 个月。治疗转移瘤的中位大小为 1.9cm；60%的转移瘤<2cm。中位总剂量为 30Gy，5 次分割；队列中有 36%的患者接受了<30Gy 的治疗。LF 的中位时间和 12 个月的 LF 累积发生率分别为 8.5 个月和 23.8%。中位死亡时间和 12 个月的总生存率分别为 11.8 个月和 48.2%。52 个转移瘤（15.6%）出现了不良反应，其中 32 个（9.5%）是症状性坏死。多变量分析发现，总剂量<30Gy 的患者 LF 更差（危险比，1.62；P=0.03），<30Gy 组患者的 6 个月和 12 个月 LF 分别为 13%和 33%，而>30Gy 组患者的 6 个月和 12 个月 LF 分别为 5%和 19%。探索性分析表明，在所有组织学类型中都观察到了剂量反应效应，包括乳腺癌亚组。
在 5 次分割每日治疗中，HSRT 剂量达到≥30Gy 时可实现最佳局部控制，与肿瘤体积和组织学无关，放射性坏死的风险可接受。
