Ugurluer Gamze, Ballerini Giorgio, Moeckli Raphael, Matzinger Oscar, Bourhis Jean, Ozsahin Mahmut
1 Department of Radiation Oncology, University Hospital Center, University of Lausanne, Lausanne - Switzerland.
Tumori. 2015 May-Jun;101(3):268-72. doi: 10.5301/tj.5000269. Epub 2015 Apr 16.
The standard treatment of anal canal cancer (ACC) is combined chemotherapy and radiation therapy (RT), which is complex because of the shape of the target volumes and the need to minimize the irradiation of normal pelvic structures. In this study we compared the dosimetric results of helical tomotherapy (HT) plans with traditional 3D conformal RT (3DRT) plans for the treatment of ACC.
Twelve patients (median age 57 years, range 38-83; F/M 8/4) treated with HT and concurrent chemotherapy for locally advanced ACC were selected. All had histologically confirmed squamous-cell carcinoma. A clinical target volume including the tumor and pelvic and inguinal lymph nodes was treated with HT to a total dose of 36 Gy in 1.8-Gy daily fractions. Then a sequential boost of 23.4 Gy in 1.8-Gy daily fractions (total dose 59.4 Gy) was delivered to the tumor and involved nodes. For all 12 patients, 3DRT plans were generated for comparison. Treatment plans were evaluated by means of standard dose-volume histograms. Dose coverage of the planning target volumes (PTVs), homogeneity index (HI), and mean doses to organs at risk (OARs) were compared.
The coverage of PTV was comparable between the two treatment plans. HI was better in the HT vs. 3DRT plans (1.25 and 3.57, respectively; p<0.0001). HT plans resulted in better sparing of OARs (p<0.0001).
HT showed superior target dose conformality and significant sparing of pelvic structures compared with 3DRT. Further investigation should determine if these dosimetric improvements will improve clinical outcomes regarding locoregional control, survival, and treatment-related acute and late morbidity.
肛管癌（ACC）的标准治疗方法是化疗联合放射治疗（RT），由于靶区的形状以及需要尽量减少对正常盆腔结构的照射，使得这种治疗较为复杂。在本研究中，我们比较了螺旋断层放射治疗（HT）计划与传统三维适形放疗（3DRT）计划在治疗ACC时的剂量学结果。
选取12例接受HT及同步化疗的局部晚期ACC患者（中位年龄57岁，范围38 - 83岁；女性/男性为8/4）。所有患者均经组织学确诊为鳞状细胞癌。采用HT对包括肿瘤及盆腔和腹股沟淋巴结的临床靶区进行治疗，总剂量36 Gy，每日分次剂量为1.8 Gy。然后对肿瘤及受累淋巴结进行序贯推量，每日分次剂量1.8 Gy，总剂量23.4 Gy（总剂量达59.4 Gy）。为这12例患者均制定了3DRT计划用于比较。通过标准剂量体积直方图对治疗计划进行评估。比较计划靶区（PTV）的剂量覆盖情况、均匀性指数（HI）以及危及器官（OAR）的平均剂量。
两种治疗计划的PTV覆盖情况相当。HT计划的HI优于3DRT计划（分别为1.25和3.57；p<0.0001）。HT计划能更好地保护OAR（p<0.0001）。
与3DRT相比，HT显示出更好的靶区剂量适形性，且能显著减少对盆腔结构的照射。进一步的研究应确定这些剂量学上的改善是否会提高局部区域控制、生存以及治疗相关的急性和晚期并发症等方面的临床疗效。
