直腸癌肛門温存手術の適応に関する検討

1)垂直扩散至低位直肠癌提提肌及外括约肌背景：括约肌间切除术（intersphincterectomy， ISR）可以获得一定程度的远端切缘，保留括约肌功能。但是，关于直肠癌如何扩散到肛管的数据仍然很少。肛管内提肛肌和外括约肌为横切肌，其表面应为ISR的手术缘。到目前为止，低位直肠癌垂直扩散到横纹肌的研究很少。目的：本研究的目的是评估低位直肠癌的垂直扩散，并确定缩短癌与横纹肌（提肌和外括约肌）之间距离的不利因素，以便更合适地选择患者进行ISR。材料与方法：取53例切除直肠标本，均为T2-3肿瘤，肿瘤下缘距齿状线2cm以内或侵犯齿状线以外。男性36例，女性17例，平均手术年龄61.5±10.4岁（32 ~ 82岁）。无患者接受术前辅助治疗。我们评估了肿瘤的垂直扩散和远端扩散。通过测量肿瘤与横纹肌之间的最短距离（T-SM距离）来估计向横纹肌（提肌或外括约肌）的垂直扩散。我们还评估了癌症如何在横纹肌（提肌或外括约肌）附近扩散。结果：15例标本出现远端扩散。15例标本远端扩散长度为4.2±3.0 mm（范围1 ~ 10 mm）。肿瘤与横纹肌之间的平均距离（T-SM距离）为9.1±7.2 mm（范围0 ~ 32 mm）。缩短T-SM距离的危险因素单因素分析显示，除高分化或中分化腺癌外的主要组织学类型、短的T-DL距离和远端扩散是缩短T-SM距离的因素。多变量分析表明，T-DL距离和远端扩散是影响T-SM距离的独立因素，无论短距离是2 mm还是5 mm。在癌对横纹肌的侵袭方式上，癌与横纹肌的距离大多在外括约肌深部短于浅部。结论：ISR治疗晚期低位直肠癌的适应症应限于下缘为口腔至齿状线，且不伴有远端扩散。在ISR期间，肛门操作应在肛门手术之前从腹部手术进行。少

1) Vertical Spread to Levator and External Sphincter of Low Rectal CancerBackground : Intersphincteric resection (ISR) enables us to obtain a certain extent of distal margin and preserve sphincter function. But, there were still little data of how low rectal cancers spread into anal canal. In the anal canal, levator and external sphincter are striated muscle, surface of which should be the surgical margin of ISR. Thus far, vertical spread of low rectal cancer to this striated muscle has little been studied.Objectives : The aim of this study is to evaluate vertical spread of low rectal cancer and to determine unfavorable factors that shorten distance between cancer and striated muscle (levator and external sphincter) as to undergo ISR with more appropriate patient selection.Materials and Methods : We conducted the specimen resected by rectal amputation from 53 patients, having T2-3 tumor and the lower edge of the tumor was within 2cm from the dentate line or invading beyond dentate line … More . They were composed of 36 males and 17 females with a mean age of 61.5±10.4 years at operation (range, 32-82 years). No patients received preoperative adjuvant therapy. We assessed both vertical spread and distal spread of the tumor. Vertical spread to striated muscle (levator or external sphincter) was estimated by measuring the shortest distance between the tumor and the striated muscle (T-SM distance). We also assessed how cancer spreads close to striated muscle (levator or external sphincter).Results : Distal spread was observed with 15 specimens. Length of distal spread in the 15 specimens was 4.2±3.0 millimeters (range, 1-10 millimeters). Mean distance between the tumor and the striated muscle (T-SM distance) was 9.1±7.2 millimeters (range, 0-32 millimeters). According to univariate analysis of risk factor shortening T-SM distance, predominant histological type excepting well or moderately differentiated adenocarcinoma, short T-DL distance and distal spread are the factor shortening T-SM distance. According to multivariate analysis, T-DL distance and distal spread is independent factor of short T-SM distance, whether the short distance is 2 millimeters or 5 millimeters. As to invading patterns of cancer to striated muscle, distance between cancer and the striated muscle were shorter in the deep part of external sphincter than the superficial part in most cases.Conclusion : Indication of ISR to advanced low rectal cancers should be limited to that lower edge was oral to dentate line and was not accompanied by distal spread. Anal manipulation during ISR should be performed from abdominal procedure prior to anal procedure. Less