Nguyen Linh N, Ang K Kian
Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston 77030, USA.
Lancet Oncol. 2002 Nov;3(11):693-701. doi: 10.1016/s1470-2045(02)00906-3.
A greater understanding of radiobiology led to the development of two classes of radiation fractionation schedules for the treatment of head and neck cancers. The aim of accelerated fractionation is to reduce tumour proliferation, which is a major cause of relapse, by shortening the total duration of radiotherapy. By contrast, hyperfractionation exploits the differential sensitivity of tumour cells and normal tissues to radiation, to increase the therapeutic gain. The results of clinical trials of various types of altered fractionation schedules in head and neck carcinomas are examined in this review. Acceleration of radiation by 1 week without dose reduction and hyperfractionation are consistently better than standard fractionation for locoregional control of intermediate to advanced carcinomas without an increase in late toxic effects. However, improvement in survival of patients has not been consistent. Clinical investigations show that improvement in locoregional disease control and consistent gain in survival have been achieved with combinations of radiotherapy and concurrent chemotherapy in patients with mostly stage IV carcinomas. However, these benefits have been at the expense of increased late morbidity. Consequently, concurrent radiochemotherapy is now preferred for non-surgical treatment of patients with locally advanced carcinomas, whereas altered fractionation is generally selected for patients with intermediate-stage tumours or who are medically unfit to receive chemotherapy. Further data is needed before the combination of altered fractionation with chemotherapy can be recommended outside of a study setting.
对放射生物学更深入的理解促使人们为头颈癌的治疗制定了两类放疗分割方案。加速分割放疗的目的是通过缩短放疗总时长来减少肿瘤增殖，而肿瘤增殖是复发的主要原因。相比之下，超分割放疗利用肿瘤细胞和正常组织对辐射的不同敏感性来提高治疗增益。本文综述了头颈癌各种类型的改变分割方案的临床试验结果。在不增加晚期毒性反应的情况下，将放疗时间加速1周且不降低剂量以及超分割放疗在局部区域控制中晚期癌方面始终优于标准分割放疗。然而，患者生存率的提高并不一致。临床研究表明，对于大多数IV期癌患者，放疗与同步化疗联合可实现局部区域疾病控制的改善和生存率的持续提高。然而，这些益处是以增加晚期发病率为代价的。因此，同步放化疗目前是局部晚期癌患者非手术治疗的首选，而改变分割放疗通常适用于中期肿瘤患者或因身体原因不适于接受化疗的患者。在研究环境之外推荐改变分割放疗与化疗联合之前，还需要更多数据。
