Hyun Kim Tae, Choi Jinho, Park Sung-Yong, Lee Seok-Ho, Lee Kyu-Chan, Yang Dae Sik, Shin Kyung Hwan, Cho Kwan Ho, Lim Hyun-Sun, Kim Joo-Young
Research Institute and Hospital, National Cancer Center, Goyang, Gyeonggi, Korea.
Cancer. 2005 Sep 15;104(6):1304-11. doi: 10.1002/cncr.21292.
Late rectal complication (LRC) was a major late complication in patients with uterine cervical carcinoma who were treated with a combination of external beam radiotherapy (EBRT) and high-dose-rate intracavitary irradiation (HDR-ICR). For the current study, the authors retrospectively evaluated dosimetric parameters that were correlated with LRC > or = Grade 2 in patients with uterine cervical carcinoma who were treated with curative radiotherapy, and they analyzed the appropriate dose estimates to the rectum that were predictive for LRC > or = Grade 2.
Between July 1994 and September 2002, 157 patients who were diagnosed with Stage IB-IIIB cervical carcinoma and were treated with definitive radiotherapy were included. EBRT (41.4-66 grays [Gy] in 23-33 fractions) to the whole pelvis was delivered to all patients, with midline shielding performed after a 36-50.4 Gy external dose. HDR-ICR (21-39 Gy in 6-13 fractions to Point A) was administered at a rate of 2 fractions weekly after midline shielding of EBRT. LRC was scored using Radiation Therapy Oncology Group criteria. The total biologically effective dose (BED) at specific points, such as Point A (BED(Point A)), rectal point (BED(RP)), and maximal rectal point (BED(MP)), was determined by a summation of the EBRT and HDR-ICR components, in which the alpha/beta ratio was set to 3. Analyzed parameters included patient age, tumor size, stage, concurrent chemotherapy, ICR fraction size, RP ratio (dose at the rectal point according to the Point A dose), MP ratio (dose at the maximal rectal point according to the Point A dose), EBRT dose, BED(Point A), BED(RP), and BED(MP).
The 5-year actuarial overall rate of LRC > or = Grade 2 in all patients was 18.4%. Univariate analysis showed that the RP ratio, MP ratio, EBRT dose, BED(Point A), BED(RP), and BED(MP) were correlated with LRC > or = Grade 2 (P < 0.05). Multivariate analysis showed that, of all clinical and dosimetric parameters evaluated, only BED(RP) was correlated with LRC > or = Grade 2 (P = 0.009). The 5-year actuarial rate of LRC > or = Grade 2 was 5.4% in patients with a BED(RP) < 125 Gy(3) and 36.1% in patients with a BED(RP) > or = 125 Gy(3) (P < 0.001).
BED(RP) was a useful dosimetric parameter for predicting the risk of LRC > or = Grade 2 and should be limited to < 125 Gy(3) whenever possible to minimize the risk of LRC > or = Grade 2 in patients with uterine cervical carcinoma who are treated with a combination of EBRT and HDR-ICR. Cancer 2005.
晚期直肠并发症（LRC）是接受外照射放疗（EBRT）和高剂量率腔内照射（HDR-ICR）联合治疗的子宫颈癌患者的主要晚期并发症。在本研究中，作者回顾性评估了接受根治性放疗的子宫颈癌患者中与≥2级LRC相关的剂量学参数，并分析了对直肠的合适剂量估计值，这些估计值可预测≥2级LRC。
纳入1994年7月至2002年9月期间诊断为IB-IIIB期宫颈癌并接受根治性放疗的157例患者。所有患者均接受全盆腔EBRT（41.4-66格雷[Gy]，分23-33次），在36-50.4 Gy外照射剂量后进行中线屏蔽。EBRT中线屏蔽后，以每周2次的频率给予HDR-ICR（A点剂量为21-39 Gy，分6-13次）。使用放射治疗肿瘤学组标准对LRC进行评分。通过将EBRT和HDR-ICR成分相加来确定特定点的总生物等效剂量（BED），如A点（BED(A点)）、直肠点（BED(RP)）和最大直肠点（BED(MP)），其中α/β比值设定为3。分析的参数包括患者年龄、肿瘤大小、分期、同步化疗、ICR分次剂量、RP比值（直肠点剂量与A点剂量之比）、MP比值（最大直肠点剂量与A点剂量之比）、EBRT剂量、BED(A点)、BED(RP)和BED(MP)。
所有患者中≥二级LRC的5年精算总发生率为18.4%。单因素分析显示，RP比值、MP比值、EBRT剂量、BED(A点)、BED(RP)和BED(MP)与≥二级LRC相关（P<0.05）。多因素分析显示，在所有评估的临床和剂量学参数中，只有BED(RP)与≥二级LRC相关（P = 0.009）。BED(RP)<125 Gy(3)的患者中≥二级LRC的5年精算发生率为5.4%，而BED(RP)≥125 Gy(3)的患者中该发生率为36.1%（P<0.001）。
BED(RP)是预测≥二级LRC风险的有用剂量学参数，对于接受EBRT和HDR-ICR联合治疗的子宫颈癌患者，应尽可能将其限制在<125 Gy(3)，以将≥二级LRC的风险降至最低。《癌症》2005年。
