Yamazaki Hideya, Suzuki Gen, Nakamura Satoaki, Yoshida Ken, Konishi Koji, Teshima Teruki, Ogawa Kazuhiko
Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajiicho Kawaramachi Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
Department of Radiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-City, Osaka, 569-8686, Japan.
J Radiat Res. 2017 Jul 1;58(4):495-508. doi: 10.1093/jrr/rrx023.
Early laryngeal, especially glottic, cancer is a good candidate for radiotherapy because obvious early symptoms (e.g. hoarseness) make earlier treatment possible and with highly successful localized control. This type of cancer is also a good model for exploring the basic principles of radiation oncology and several key findings (e.g. dose, fractionation, field size, patient fixation, and overall treatment time) have been noted. For example, unintended poor outcomes have been reported during transition from 60Cobalt to linear accelerator installation in the 1960s, with usage of higher energy photons causing poor dose distribution. In addition, shell fixation made precise dose delivery possible, but simultaneously elevated toxicity if a larger treatment field was necessary. Of particular interest to the radiation therapy community was altered fractionation gain as a way to improve local tumor control and survival rate. Unfortunately, this interest ceased with advancements in chemotherapeutic agents because alternate fractionation could not improve outcomes in chemoradiotherapy settings. At present, no form of acceleration can potentially compensate fully for the lack of concurrent chemotherapy. In addition, the substantial workload associated with this technique made it difficult to add extra fractionation routinely in busy clinical hospitals. Hypofractionation, on the other hand, uses a larger single fractionation dose (2-3 Gy), making it a reasonable and attractive option for T1-T2 early glottic cancer because it can improve local control without the additional workload. Recently, Japan Clinical Oncology Group study 0701 reprised its role in early T1-T2 glottic cancer research, demonstrating that this strategy could be an optional standard therapy. Herein, we review radiotherapy history from 60Cobalt to modern linear accelerator, with special focus on the role of alternate fractionation.
早期喉癌，尤其是声门癌，是放射治疗的良好适应证，因为明显的早期症状（如声音嘶哑）使早期治疗成为可能，并且局部控制成功率很高。这种癌症也是探索放射肿瘤学基本原理的良好模型，并且已经有了一些关键发现（如剂量、分割方式、照射野大小、患者固定以及总治疗时间）。例如，在20世纪60年代从钴 - 60放疗设备向直线加速器过渡期间，曾报道出现意外的不良结果，使用更高能量的光子导致剂量分布不佳。此外，外壳固定使精确的剂量输送成为可能，但如果需要更大的治疗野，同时会增加毒性。放射治疗界特别感兴趣的是改变分割方式以提高局部肿瘤控制率和生存率。不幸的是，随着化疗药物的进展，这种兴趣消失了，因为在放化疗环境中改变分割方式并不能改善治疗结果。目前，没有任何一种加速方式能够完全弥补同步化疗的缺失。此外，与该技术相关的大量工作量使得繁忙的临床医院难以常规增加额外的分割次数。另一方面，大分割放疗使用更大的单次分割剂量（2 - 3 Gy），对于T1 - T2期早期声门癌来说是一种合理且有吸引力的选择，因为它可以提高局部控制率且无需额外的工作量。最近，日本临床肿瘤学组的0701研究再次在早期T1 - T2期声门癌研究中发挥作用，表明这种策略可能成为一种可选的标准治疗方法。在此，我们回顾从钴 - 60放疗设备到现代直线加速器的放疗历史，特别关注改变分割方式的作用。
