Gu Chaoyang, Yang Xuyang, Zhang Xubing, Zheng Erliang, Deng Xiangbing, Hu Tao, Wu Qingbin, Bi Liang, Wu Bing, Su Minggang, Wang Ziqiang
Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, No. 37 Guo Xue Alley.
West China School of Medicine, Sichuan University.
Medicine (Baltimore). 2018 Nov;97(48):e13468. doi: 10.1097/MD.0000000000013468.
Previous studies suggested that the extramural distance (EMD) should be considered in therapeutic decision-making of rectal cancer because it can be used as an indicator of the T3 subclassification; however, reports of impact of EMD/mesorectum ratio on prognosis are rare.The objectives of this study were to evaluate the feasibility of the extramural distance EMD/mesorectum ratio as a maker of the T3 subclassification for T3 mid-low rectal cancer and find the potential radiological marker on MRI for neoadjuvant chemoradiotherapy (nCRT).From December 2012 to December 2016, 287 consecutive patients with MRI-staged T3 mid-low rectal cancer were enrolled. The EMD was defined as the distance from the outer edge of the muscularis propria to the outer edge of tumor, and the mesorectum was measured as the distance from outer edge of muscularis propria to mesorectal fascia (MRF) in the same layer. The association of the EMD/mesorectum ratio and other MRI or clinicopathological factors with survival was analyzed. The independent prognostic factors were estimated by Cox regression analysis.The mean EMD/mesorectum ratio was 0.43. Based on ROC analysis, we chose a EMD/mesorectum ratio of 0.3 for further analyses. Of 287 patients, 163 (56.8%) had a EMD/mesorectum ratio ≥ 0.3. Patients with an EMD/mesorectum ratio ≥ 0.3 had a decreased recurrence free survival (RFS) and overall survival (OS) (P < .001; P = .034, respectively). Of the 163 patients, patients with nCRT had a higher RFS than patients without nCRT (P = .001). Multivariate analysis showed that the EMD/mesorectum ratio was the only independent prognostic factors for RFS.Our study provided evidence that the EMD/mesorectum ratio could be used for T3 subclassification, the optimal cut-off value of EMD/mesorectum ratio was 0.3 when the ratio was applied to classify T3 mid-low rectal cancer patients, and nCRT should be performed for these patients when the EMD/mesorectum ratio is ≥ 0.3.
既往研究表明，在直肠癌治疗决策中应考虑壁外距离（EMD），因为它可作为T3亚分类的一个指标；然而，关于EMD/直肠系膜比率对预后影响的报道很少。本研究的目的是评估壁外距离EMD/直肠系膜比率作为T3中低位直肠癌T3亚分类标志物的可行性，并在磁共振成像（MRI）上找到新辅助放化疗（nCRT）的潜在影像学标志物。2012年12月至2016年12月，连续纳入287例MRI分期为T3中低位直肠癌患者。EMD定义为固有肌层外缘至肿瘤外缘的距离，直肠系膜测量为同一层面固有肌层外缘至直肠系膜筋膜（MRF）的距离。分析EMD/直肠系膜比率及其他MRI或临床病理因素与生存的相关性。通过Cox回归分析估计独立预后因素。EMD/直肠系膜比率的平均值为0.43。基于ROC分析，我们选择EMD/直肠系膜比率为0.3进行进一步分析。287例患者中，163例（56.8%）的EMD/直肠系膜比率≥0.3。EMD/直肠系膜比率≥0.3的患者无复发生存期（RFS）和总生存期（OS）降低（P<0.001；P=0.034）。在这163例患者中，接受nCRT的患者RFS高于未接受nCRT的患者（P=0.001）。多因素分析显示，EMD/直肠系膜比率是RFS的唯一独立预后因素。我们的研究提供了证据表明，EMD/直肠系膜比率可用于T3亚分类，当该比率用于对T3中低位直肠癌患者进行分类时，EMD/直肠系膜比率的最佳截断值为0.3，当EMD/直肠系膜比率≥0.3时，应对这些患者进行nCRT。
