Tatekawa Kotoha, Iwata Hiromitsu, Kawaguchi Takatsune, Ishikura Satoshi, Baba Fumiya, Otsuka Shinya, Miyakawa Akifumi, Iwana Maho, Shibamoto Yuta
Department of Radiology, Nagoya City University Hospital, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.
Radiat Oncol. 2014 Jan 7;9:8. doi: 10.1186/1748-717X-9-8.
The overall treatment time of stereotactic body radiotherapy (SBRT) for non-small-cell lung cancer is usually 3 to over 10 days. If it is longer than 7 days, tumor volume expansion during SBRT may jeopardize the target dose coverage. In this study, volume change of stage I NSCLC during SBRT was investigated.
Fifty patients undergoing 4-fraction SBRT with a total dose of 48 Gy (n = 36) or 52 Gy (n = 14) were analyzed. CT was taken for registration at the first and third SBRT sessions with an interval of 7 days in all patients. Patient age was 29-87 years (median, 77), and 39 were men. Histology was adenocarcinoma in 28, squamous cell carcinoma in 17, and others in 5. According to the UICC 7th classification, T-stage was T1a in 9 patients, T1b in 27, and T2a in 14. Tumor volumes on the first and 8th days were determined on CT images taken during the exhalation phase, by importing the data into the Dr. View/LINAX image analysis system. After determining the optimal threshold for distinguishing tumor from pulmonary parenchyma, the region above -250 HU was automatically extracted and the tumor volumes were calculated.
The median tumor volume was 7.3 ml (range, 0.5-35.7) on day 1 and 7.5 ml (range, 0.5-35.7) on day 8. Volume increase of over 10% was observed in 16 cases (32%); increases by >10 to ≤ 20%, >20 to ≤ 30%, and >30% were observed in 9, 5, and 2 cases, respectively. The increase in the estimated tumor diameter was over 2 mm in 3 cases and 1-2 mm in 6. A decrease of 10% or more was seen in 3 cases. Among the 16 tumors showing a volume increase of over 10%, T-stage was T1a in 2 patients, T1b in 9, and T2a in 5. Histology was adenocarcinoma in 10 patients, squamous cell carcinoma in 5, and others in 1.
Volume expansion >10% was observed in 32% of the tumors during the first week of SBRT, possibly due to edema or sustained tumor progression. When planning SBRT, this phenomenon should be taken into account.
非小细胞肺癌立体定向体部放射治疗（SBRT）的总治疗时间通常为3至10多天。如果超过7天，SBRT期间肿瘤体积扩大可能会危及靶区剂量覆盖。本研究调查了I期非小细胞肺癌在SBRT期间的体积变化。
分析了50例接受4次分割SBRT的患者，总剂量为48 Gy（n = 36）或52 Gy（n = 14）。所有患者在第1次和第3次SBRT治疗时进行CT扫描以进行配准，间隔7天。患者年龄为29 - 87岁（中位数77岁），男性39例。组织学类型为腺癌28例，鳞癌17例，其他5例。根据国际抗癌联盟（UICC）第7版分类，T分期为T1a 9例，T1b 27例，T2a 14例。在呼气期采集的CT图像上确定第1天和第8天的肿瘤体积，将数据导入Dr. View/LINAX图像分析系统。确定区分肿瘤与肺实质的最佳阈值后，自动提取高于 -250 HU的区域并计算肿瘤体积。
第1天的肿瘤体积中位数为7.3 ml（范围0.5 - 35.7），第8天为7.5 ml（范围0.5 - 35.7）。16例（32%）观察到体积增加超过10%；分别有9例、5例和2例体积增加>10%至≤20%、>20%至≤30%和>30%。估计肿瘤直径增加超过2 mm的有3例，增加1 - 2 mm的有6例。3例体积减少10%或更多。在16例体积增加超过10%的肿瘤中，T分期为T1a 2例，T1b 9例，T2a 5例。组织学类型为腺癌10例，鳞癌5例，其他1例。
32%的肿瘤在SBRT的第一周内观察到体积扩大超过10%，可能是由于水肿或肿瘤持续进展。在制定SBRT计划时，应考虑到这一现象。
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