Sanguineti Giuseppe, Gunn G Brandon, Endres Eugene J, Chaljub Gregory, Cheruvu Praveena, Parker Brent
Department of Radiation Oncology, University of Texas Medical Branch, Galveston, TX, USA.
Int J Radiat Oncol Biol Phys. 2008 Nov 1;72(3):737-46. doi: 10.1016/j.ijrobp.2008.01.027. Epub 2008 May 15.
To assess the patterns of failure after intensity-modulated radiotherapy (IMRT) for oropharyngeal squamous cell carcinoma (SCC).
We analyzed patients treated at the University of Texas Medical Branch between May 2002 and February 2006 who met the following criteria: (1) definitive IMRT without chemotherapy for oropharyngeal SCC; (2) no pretreatment radical surgery; (3) minimal follow-up of 1 year. The location of each nodal/primary failure was co-registered to the pretreatment planning computed tomography scan and then expanded by 5 mm to a planning target volume (PTV) of the failure (PTV-f). We then investigated whether the prescription dose to the PTV-f had been appropriate for the amount of disease present before treatment and whether the PTV-f had been adequately covered.
A total of 50 patients were eligible. With a median follow-up of 32.6 months (range, 12.1-58.6), three local and six regional failures were observed in 8 patients. All but one failure, that had been neglected, were recorded within 14 months of the treatment end. Of the nine failures, four developed in the neck treated electively to the lowest dose level; in all of them, we could retrospectively identify initial positive lymph nodes that might have justified the subsequent failure. The remaining five failures developed in proximity of the high-dose volume. In all but one, the volume of region of interest receiving >/=95% of the dose of the PTV-f was >95%, suggesting adequate coverage. In 1 patient, about 20% of PTV-f was outside the 95% isodose, so that marginal underdosing could not be ruled out.
A potential cause could be identified in all the failures in the lowest dose level. The implications and possible remedies are discussed. Most failures around the high-dose region were "true failures" with no apparent technical cause.
评估口咽鳞状细胞癌（SCC）调强放疗（IMRT）后的失败模式。
我们分析了2002年5月至2006年2月在德克萨斯大学医学分校接受治疗且符合以下标准的患者：（1）口咽SCC接受单纯IMRT且未化疗；（2）治疗前未行根治性手术；（3）最短随访1年。将每个淋巴结/原发灶失败部位与治疗前计划计算机断层扫描进行配准，然后向外扩展5mm形成失败部位的计划靶体积（PTV-f）。然后我们研究PTV-f的处方剂量对于治疗前存在的疾病量是否合适，以及PTV-f是否得到了充分覆盖。
共有50例患者符合条件。中位随访时间为32.6个月（范围12.1 - 58.6个月），8例患者出现3例局部失败和6例区域失败。除1例被遗漏的失败外，所有失败均在治疗结束后14个月内记录。在9例失败中，4例发生在接受最低剂量水平选择性照射的颈部；在所有这些病例中，我们可以回顾性地识别出可能导致后续失败的初始阳性淋巴结。其余5例失败发生在高剂量体积附近。除1例患者外，接受≥PTV-f剂量95%的感兴趣区域体积均>95%，提示覆盖充分。1例患者中，约20%的PTV-f超出95%等剂量线，因此不能排除边缘剂量不足。
在最低剂量水平的所有失败中均可识别出潜在原因。讨论了其影响及可能的补救措施。高剂量区域周围的大多数失败是“真正的失败”，没有明显的技术原因。
