Wang Gang, Wang Wenling, Jin Haijie, Dong Hongmin, Chen Weiwei, Li Xiaokai, Bai Saixi, Li Guodong, Chen Wanghua, Li Leilei, Chen Juan
Department of Abdominal Oncology, The Affiliated Hospital of Guizhou Medical University, The Affiliated Cancer Hospital of Guizhou Medical University, Guiyang, China.
Front Oncol. 2022 Feb 23;12:843704. doi: 10.3389/fonc.2022.843704. eCollection 2022.
To effectively reduce the irradiated bowel volume so as to reduce intestinal toxicity from pelvic radiotherapy, treatment in the prone position with a full bladder on a belly board is widely used in pelvic radiotherapy for rectal cancer patients. However, the clinical applicable condition of this radiotherapy mode is unclear. The aim of this study was to preliminarily identify patients who were not eligible for this radiotherapy mode by analyzing the effect of abdominal circumference on the irradiated bowel volume.
From May 2014 to September 2019, 179 patients with locally advanced rectal cancer were retrospectively reviewed in our center. All patients received pelvic radiotherapy. Weight, height, AC, and body mass index (BMI) were used as the research objects, and the irradiated bowel volume at different dose levels (V10, V20, V30, V40, V50) was selected as the outcome variable. Multivariate linear regression and sensitivity analyses were used to evaluate the correlation between AC and irradiated bowel volume. Generalized additive model (GAM) and piecewise linear regression were used to further analyze the possible nonlinear relationship between them.
Among the four body size indicators, AC showed a negative linear correlation with the irradiated bowel volume, which was the most significant and stable. In adjuvant radiotherapy patients, we further discovered the threshold effect between AC and irradiated bowel volume, as AC was greater than the inflection point (about 71 cm), irradiated bowel volume decreased rapidly with the increase in AC. -test showed that in patients with small AC (<71 cm), the irradiated bowel volume was significantly higher than that of patients with medium-large AC (≥71 cm). Especially in patients with adjuvant radiotherapy, the mean irradiated bowel volume of patients with small AC was the highest in this study. Compared with adjuvant radiotherapy, in neoadjuvant radiotherapy, the mean difference of irradiated bowel volume between patients with medium-large AC and those with small AC was larger.
AC is an independent factor influencing the irradiated bowel volume and has a strong negative linear correlation with it. Patients with small AC may not benefit from this common mode of radiotherapy, especially in adjuvant radiotherapy.
为有效减少受照射肠体积，从而降低盆腔放疗所致的肠道毒性，直肠癌患者盆腔放疗广泛采用俯卧位并在腹托上保持膀胱充盈的治疗方式。然而，这种放疗模式的临床适用条件尚不清楚。本研究旨在通过分析腹围对受照射肠体积的影响，初步确定不适合这种放疗模式的患者。
2014年5月至2019年9月，对本中心179例局部晚期直肠癌患者进行回顾性研究。所有患者均接受盆腔放疗。选取体重、身高、腹围（AC）和体重指数（BMI）作为研究对象，选取不同剂量水平（V10、V20、V30、V40、V50）下的受照射肠体积作为结局变量。采用多变量线性回归和敏感性分析评估AC与受照射肠体积之间的相关性。使用广义相加模型（GAM）和分段线性回归进一步分析它们之间可能存在的非线性关系。
在四个身体尺寸指标中，AC与受照射肠体积呈负线性相关，且最为显著和稳定。在辅助放疗患者中，我们进一步发现了AC与受照射肠体积之间的阈值效应，当AC大于拐点（约71 cm）时，受照射肠体积随AC增加而迅速下降。t检验显示，AC较小（<71 cm）的患者，其受照射肠体积显著高于中-大AC（≥71 cm）的患者。特别是在辅助放疗患者中，AC较小的患者平均受照射肠体积在本研究中最高。与辅助放疗相比，在新辅助放疗中，中-大AC患者与小AC患者之间受照射肠体积的平均差异更大。
AC是影响受照射肠体积的独立因素，且与之呈强负线性相关。AC较小的患者可能无法从这种常见的放疗模式中获益，尤其是在辅助放疗中。
