食管癌放射治疗非常规分次方案的剂量—效应分析

Results of unconventional fractionated radiotherapy for esophageal carcinoma

目的 对近年国内报道的食管癌非常规分次方案进行剂量—效应分析 ,探索改善放射治疗疗效较合理的方案。方法 收集 1989年以来食管癌非常规分次 (ICF)照射和以常规剂量分次(CF)作为对照的前瞻性随机分组结果 ,比较肿瘤局部控制率或 (及 )生存率。依LQ模式计算各个方案对肿瘤组织的放射生物学效应剂量 (BEDT)值 ,与各自的CF对照组进行剂量—效应比较。结果 超分割 (HF) 3个组中有 2个组疗效显著提高 ,其BEDT 值分别高出 5 + 、10Gy ;疗效无差异 1个组BEDT值降低 6 .8Gy。加速超分割 (AHF) 2个组中 1个组BEDT 值降低 17.2Gy,疗效无差异 ;1个组疗效显著提高不能用BEDT 值降低 11.3Gy来解释。后程加速超分割 (LAHF)的 7个组中 ,疗效显著提高的有 6个组 ,其BEDT 值比较不能用于预测LAHF对CF方案的疗效差别。后程加速分割 (LAF) 1个组BEDT值仅高出 2 .8Gy,但 1、3年生存率提高非常显著。前程加速分割 (EAF) 1个组的已知疗终完全缓解率提高的相关因素是剂量高出 6 .8Gy。结论 (1)用ICF方案有可能在肿瘤局部控制率、生存率方面显著高于CF6 0～ 70Gy,6～ 7周方案者。 (2 )AHF、LAHF和LAF的疗效显著提高不能用该方案的BEDT 值来解释和预测 ,疗效的显著改善不依赖于剂量的增加。 (3)

Objective Results of unconventiioal fractionated (NCF) radiotherapy for esophageal carcinoma are presented to assess its validity. Methods Fourteen clinical randomized trials , carried out from 1989 to 2000,were collected from the literature for analysis. These unconventional fractionated trials were compared as to their conventrional fractionated (CF) controls of 60～70?Gy/6～7w. Among these 14 trials, 3 were hyperfractionated (HF), 2 accelerated hyperfractionated (AHF), 7 late AHF (LAHF), 1 late AF (LAF) and 1 early AF (EAF). According to the LQ formula with a tumor α/β=10 ?Gy, the radiation biological effective dose value to tumor tissue (BEDT) were calculated in all these schedules, and dose response analyses were made and compared. Results Radiation treatment results were superior to those of CF in 2 of the HF trials which gave higher BEDT value of 5 + and 10?Gy, though not significantly different (NS) in 1 which showed a BEDT 6.8?Gy lower. In 2 AHF trials, 1 NS with a BEDT 17.2?Gy lower, 1 gave significantly improved results which could not be explained by BEDT 11.3?Gy lower. For LAHF trials, 6 showed markedly increased local control and/or survival rates which could not be explained by similar BEDT value level to their CF control, and also so in the same 1 LAF trial. BEDT 6.8?Gy higher was the sole known factor for higher complete regression rate in an EAF trial. Conclusions (1) Some NCF radiotherapy schedules such as HF, AHF, LAHF and LAF can result in better local tumor control and/or survival rates than those of their CF control with 60～70?Gy/6～7week. (2) AHF, LAHF and LAF schedules are able to improve markedly the treatment outcome which may not be explained and predicted by their relative BEDT values to the control, and thus are dose independent. (3) Tumor cells present accelerated repopulation round 4±1 weeks after the start of irradiation, cell cycle phase redistribution, together with reoxygenation, making the tumor cells resensitized to radiation killing. (4) The time that tumor cells reach their highest reproductive capacity after irradiation is at the late course of radiotherapy. Most of the late accelerated schedules initially gave CF of 30～40?Gy/3～4w, then altered to be accelerated, which could increase the therapeutic gain (TG) and improve their treatment results significantly,which is the radiobiological basis for better treatment results of some types of NCF radiotherapy schedules.