Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.
Int J Radiat Oncol Biol Phys. 2012 Jul 15;83(4):1257-63. doi: 10.1016/j.ijrobp.2011.09.047. Epub 2011 Nov 16.
We investigated the clinical and dosimetric predictors for radiation-associated femoral fractures in patients with proximal lower extremity soft tissue sarcomas (STS).
We examined 131 patients with proximal lower extremity STS who received limb-sparing surgery and external-beam radiation therapy between 1985 and 2006. Five (4%) patients sustained pathologic femoral fractures. Dosimetric analysis was limited to 4 fracture patients with full three-dimensional dose information, who were compared with 59 nonfracture patients. The mean doses and volumes of bone (V(d)) receiving specified doses (≥30 Gy, 45 Gy, 60 Gy) at the femoral body, femoral neck, intertrochanteric region, and subtrochanteric region were compared. Clinical predictive factors were also evaluated.
Of 4 fracture patients in our dosimetric series, there were three femoral neck fractures with a mean dose of 57.6 ± 8.9 Gy, V30 of 14.5 ± 2.3 cc, V45 of 11.8 ± 1.1 cc, and V60 of 7.2 ± 2.2 cc at the femoral neck compared with 22.9 ± 20.8 Gy, 4.8 ± 5.6 cc, 2.5 ± 3.9 cc, and 0.8 ± 2.7 cc, respectively, for nonfracture patients (p < 0.03 for all). The femoral neck fracture rate was higher than at the subtrochanteric region despite lower mean doses at these subregions. All fracture sites received mean doses greater than 40 Gy. Also, with our policy of prophylactic femoral intramedullary nailing for high-risk patients, there was no significant difference in fracture rates between patients with and without periosteal excision. There were no significant differences in age, sex, tumor size, timing of radiation therapy, and use of chemotherapy between fracture and nonfracture patients.
These dose-volume toxicity relationships provide RT optimization goals to guide future efforts for reducing pathologic fracture rates. Prophylactic femoral intramedullary nailing may also reduce fracture risk for susceptible patients.
我们研究了接受保肢手术和外照射放疗的近端下肢软组织肉瘤（STS）患者中与放疗相关的股骨骨折的临床和剂量学预测因素。
我们检查了 1985 年至 2006 年间接受保肢手术和外照射放疗的 131 例近端下肢 STS 患者。其中 5 例（4%）患者发生病理性股骨骨折。剂量学分析仅限于 4 例骨折患者，他们有完整的三维剂量信息，并与 59 例非骨折患者进行比较。比较了股骨体、股骨颈、转子间区和转子下区的骨（V(d)）接受特定剂量（≥30Gy、45Gy、60Gy）的平均剂量和体积。还评估了临床预测因素。
在我们的剂量学系列中，4 例骨折患者中有 3 例为股骨颈骨折，股骨颈的平均剂量为 57.6 ± 8.9Gy，V30 为 14.5 ± 2.3cc，V45 为 11.8 ± 1.1cc，V60 为 7.2 ± 2.2cc，而非骨折患者的 V30 为 22.9 ± 20.8Gy，V45 为 4.8 ± 5.6cc，V60 为 2.5 ± 3.9cc，V60 为 0.8 ± 2.7cc（p < 0.03 均）。尽管这些亚区的平均剂量较低，但股骨颈骨折的发生率仍高于转子下区。所有骨折部位的平均剂量均大于 40Gy。此外，由于我们对高危患者预防性股骨髓内钉的政策，有骨膜切除的患者和没有骨膜切除的患者的骨折发生率没有显著差异。骨折患者和非骨折患者在年龄、性别、肿瘤大小、放疗时间和化疗使用方面无显著差异。
这些剂量-体积毒性关系为指导未来降低病理性骨折发生率的放射治疗优化目标提供了依据。预防性股骨髓内钉固定也可能降低易感患者的骨折风险。
