Petereit D G, Pearcey R
University of Wisconsin Medical School, Madison, USA.
Int J Radiat Oncol Biol Phys. 1999 Jan 15;43(2):359-66. doi: 10.1016/s0360-3016(98)00387-3.
A literature review and analysis was performed to determine whether or not efficacious high dose rate (HDR) brachytherapy fractionation schedules exist for the treatment of cervical cancer.
English language publications from peer reviewed journals were assessed to calculate the total contribution of dose to Point A from both the external and intracavitary portions of radiation for each stage of cervical cancer. Using the linear quadratic formula, the biologically effective dose to the tumor, using an alpha/beta = 10, was calculated to Point A (Gy10) in order to determine a dose response relationship for local control and survival. Significant complications were assessed by calculating the dose to the late-responding tissues at Point A using an alpha/beta = 3 (Gy3) as a surrogate for normal tissue tolerance, since few publications list the actual bladder and rectal doses.
For all stages combined, the median external beam fractionation schedule to Point A was 40 Gy in 20 fractions, while the median HDR fractionation schedule was 28 Gy in 4 fractions. For stages IB, IIB, and IIIB the median biologically effective dose to Point A (Gy10) was 96, 96 and 100 Gy10s, respectively. No correlation was identified between Point A BED (Gy10s) to either survival or pelvic control. A dose response relationship could also not be identified when correlating Point A Gy3s to complications.
A dose response relationship could not be identified for either tumor control nor late tissue complications. These findings do not necessarily question the validity of the linear quadratic model, as much as they question the quality of the current HDR brachytherapy literature as it is currently presented and reported. Most of the HDR publications report inadequate details of the dose fractionation schedules. Only a minority of publications report significant complications using the actuarial method. In the future, all HDR publications for the treatment of cervical cancer should provide accurate fractionation details for each stage of disease, while reporting actuarial complication rates. The optimal fractionation schedule for treating cervical cancer using HDR brachytherapy is still unknown, and presently can be based only on single institutions with significant experience.
进行文献综述与分析，以确定是否存在用于治疗宫颈癌的有效高剂量率（HDR）近距离放射治疗分割方案。
评估同行评审期刊上的英文出版物，计算宫颈癌各阶段放疗的体外和腔内部分对A点的总剂量贡献。使用线性二次公式，以α/β = 10计算肿瘤的生物等效剂量，得出A点的Gy10，以确定局部控制和生存的剂量反应关系。由于很少有出版物列出实际的膀胱和直肠剂量，通过以α/β = 3计算A点晚期反应组织的剂量（Gy3）来评估显著并发症，以此作为正常组织耐受的替代指标。
综合所有阶段，体外照射至A点的中位分割方案为20次分割共40 Gy，而高剂量率近距离放射治疗的中位分割方案为4次分割共28 Gy。对于IB期、IIB期和IIIB期，A点的中位生物等效剂量（Gy10）分别为96、96和100 Gy10。未发现A点生物等效剂量（Gy10）与生存或盆腔控制之间存在相关性。将A点的Gy3与并发症相关联时，也未发现剂量反应关系。
在肿瘤控制和晚期组织并发症方面均未发现剂量反应关系。这些发现不一定质疑线性二次模型的有效性，更多的是质疑当前高剂量率近距离放射治疗文献的呈现和报告质量。大多数高剂量率出版物报告的剂量分割方案细节不足。只有少数出版物使用精算方法报告显著并发症。未来，所有用于治疗宫颈癌的高剂量率出版物都应提供疾病各阶段准确的分割细节，同时报告精算并发症发生率。使用高剂量率近距离放射治疗宫颈癌的最佳分割方案仍然未知，目前只能基于有丰富经验的单一机构。
