Thiagarajan Anuradha, Pan Larry, Zatcky Joan, Krol George, Boland Patrick J, Yamada Yoshiya
Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10021, USA.
Department of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Drive, 169610, Singapore.
J Radiosurg SBRT. 2014;3(1):59-65.
There is little data on sacral insufficiency fracture(SIF) incidence following pelvic radiotherapy, with existing studies based on conventional fractionation. Stereotactic body radiotherapy (SBRT), characterized by dose escalation with hypofractionation, may pose even greater risks to sacral integrity. This study aims to define SIF incidence and risk factors following SBRT.
Records of 43 consecutive patients who underwent sacral SBRT from September 2005-May 2009 were reviewed. Baseline patient information (age, gender, menopausal status, body mass index, use of bone-thinning agents, presence of osteoporosis), tumor characteristics (histology, lesion appearance and extent) and treatment parameters (dose/fractionation, prior radiation/surgery) were documented. Primary end-point was development of new fractures or progression of pre-existing fractures. Secondary end-points included pain scores, analgesic use, functional ability, and local tumor control.
Median follow-up was 17months. Common histologies included sarcoma, renal cell, and prostate carcinoma; 47% of lesions were lytic, 37% sclerotic and the remainder mixed. Doses ranged from 18-24Gy/1fraction to 30Gy/5fractions with 45% receiving single fractions.14% had prior radiation (median dose: 30Gy/10fractions).Five patients developed SIF. In four, fractures occurred in the context of controlled local disease. Median time to SIF was 8.2months. Symptoms varied from minimal pain requiring no intervention to severe pain impacting on function. Two patients underwent sacroplasty due to intractable pain, with both obtaining good analgesia. Low event numbers precluded meaningful univariate/multivariate analyses. One-year local tumor control rates were excellent (91.7%).
In this study, actuarial SIF incidence at one year was 8.2%, suggesting that SIF risk from sacral SBRT is low. However, larger prospective studies with longer follow-up are needed. In addition, novel therapies such as sacroplasty need further study to determine safety, efficacy and indications for use.
关于盆腔放疗后骶骨不全骨折（SIF）的发生率数据很少，现有研究基于传统分割放疗。立体定向体部放疗（SBRT）的特点是采用大分割增加剂量，可能对骶骨完整性造成更大风险。本研究旨在确定SBRT后的SIF发生率及危险因素。
回顾了2005年9月至2009年5月期间连续43例行骶骨SBRT患者的记录。记录了患者的基线信息（年龄、性别、绝经状态、体重指数、使用骨量减少药物情况、骨质疏松情况）、肿瘤特征（组织学类型、病变表现及范围）和治疗参数（剂量/分割、既往放疗/手术情况）。主要终点是新发骨折或既往骨折进展。次要终点包括疼痛评分、镇痛药物使用、功能能力和局部肿瘤控制情况。
中位随访时间为17个月。常见组织学类型包括肉瘤、肾细胞癌和前列腺癌；47%的病变为溶骨性，37%为硬化性，其余为混合性。剂量范围为18 - 24Gy/1次分割至30Gy/5次分割，45%的患者接受单次分割。14%的患者既往接受过放疗（中位剂量：30Gy/10次分割）。5例患者发生SIF。其中4例在局部疾病得到控制的情况下发生骨折。SIF的中位发生时间为8.2个月。症状从无需干预的轻微疼痛到影响功能的严重疼痛不等。2例患者因顽固性疼痛接受了骶骨成形术，均获得了良好的镇痛效果。由于事件数量较少，无法进行有意义的单因素/多因素分析。一年局部肿瘤控制率极佳（91.7%）。
在本研究中，一年时SIF的精算发生率为8.2%，提示骶骨SBRT导致SIF的风险较低。然而，需要进行更大规模、随访时间更长的前瞻性研究。此外，骶骨成形术等新疗法需要进一步研究以确定其安全性、有效性及使用指征。
