Lateral pelvic lymph node dissection or chemoradiotherapy: which is the procedure of choice to reduce local recurrence rate in lower rectal cancer?
Lateral pelvic lymph node dissection or chemoradiotherapy: which is the procedure of choice to reduce local recurrence rate in lower rectal cancer?
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盆腔外侧淋巴结清扫术或放化疗：哪种是降低低位直肠癌局部复发率的选择？
DOI：
10.1097/sla.0b013e3181820d0d
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发表时间：
2008
影响因子：
9
通讯作者：
T. Kobunai
中科院分区：
文献类型：
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作者：
Toshiaki Watanabe;K. Matsuda;K. Nozawa;T. Kobunai
致编辑：我们饶有兴趣地阅读了Kim等人在最近一期《外科年鉴》上发表的论文，"直肠癌全直肠系膜切除术后放化疗和盆腔淋巴结清扫的比较结果"。Kim等表明，放化疗（CRT）对减少局部复发和提高生存率都是有用的。作者在文章中介绍了我们的研究。我们同意放射治疗对降低局部复发率是有效的，尽管我们使用术前而不是术后放射治疗，这在Kim博士的研究中使用。Kim等人比较了盆腔外侧淋巴结清扫术（LPLD）组和术后CRT组的患者结局。在III期低位直肠癌中，他们成功地证明了LPLD组的局部复发率比CRT组高2.2倍。他们得出结论，患者需要辅助CRT以减少LPLD后局部复发。这项研究解决了一个重要的问题，因为很少有研究比较LPLD和放疗的疗效。然而，要得出上述结论，本研究还有一些主要问题需要讨论。最重要的一点是，LPLD组的局部复发率远高于东京驹目医院同一日本组先前报道的复发率。该小组多年来一直报告LPLD降低局部复发率的疗效，并在2005年发表的报告中报告III期低位直肠癌的5年局部复发率仅为7.4%。然而，在2007年发表的Kim的研究中，同一组报告说，III期低位直肠癌患者的5年局部复发率为16.7%。在如此短的时间内，局部复发率不太可能从7.4%变为16.7%。这是因为患者的选择偏倚还是由于对“局部复发”的不同定义？这一点需要澄清。第二点与术后辅助化疗有关。先前的随机对照研究和荟萃分析表明，直肠癌的辅助化疗可提高总体生存率和无病生存率，并降低局部复发率。这些研究表明，辅助化疗显著影响直肠癌患者的术后结局。然而，Kim的研究并没有提到任何辅助化疗。有必要考虑各组中实际接受术后辅助化疗的患者百分比，以比较术后结局。第三点是，由于对"低位直肠癌"的定义不同，LPLD组和CRT组在"低位直肠癌患者"方面似乎存在显著的选择偏倚。在Kim的研究中，位于腹膜反射下的病变被归类为“低位直肠癌”。然而，在日本，“低位直肠癌”的定义是不同的。根据"JSCCR发布的日本结直肠癌分类"，肿瘤位置是由"中心"而不是肿瘤的下边缘确定的。因此，如果肿瘤的中心位于腹膜反折上方，则延伸至腹膜反折下方的肿瘤被归类为"上部直肠癌"。此外，根据日本指南（JSCCR 2005年结直肠癌治疗指南），LPLD的适应症是"延伸至腹膜反射以下的T3或T4病变"。Kim等人指出，LPLD组中33%的肿瘤为"上直肠癌"，67%为"下直肠癌"。然而，由于进行了LPLD，LPLD组中的所有病变（100%）都被认为延伸到腹膜反折以下，并且根据Kim的分类应归类为“低位直肠癌”。也就是说，16.7%实际上不是LPLD组中"低位直肠癌"的局部复发率，而是LPLD组中"极低位直肠癌"的局部复发率。两个国家对"低位直肠癌"定义的双重标准似乎导致了两组"低位直肠癌"局部复发率评估的显著偏倚。在最近的荷兰试验报告中，肿瘤的位置是由肿瘤与肛缘之间的距离确定的，作者证明，位于肛缘5 cm以内的肿瘤的局部复发率明显高于5 cm以上的肿瘤。为了消除Kim研究中的显著选择偏差，他们需要通过根据肿瘤与肛门边缘之间的距离对肿瘤进行分类来比较LPLD和CRT组之间的局部复发率。我们同意Kim等人的观点，即放射治疗在改善直肠癌患者的预后方面是有用的。然而，这些观点需要澄清，以得出结论，LPLD确实显示出比CRT更高的局部复发率。
To the Editor: We read with interest the paper by Kim et al, “Comparative Outcome Between Chemoradiotherapy and Lateral Pelvic Lymph Node Dissection Following Total Mesorectal Excision in Rectal Cancer” in the recent issue of Annals of Surgery. Kim et al showed that chemoradiotherapy (CRT) is both useful to reduce local recurrence and improve survival. The authors introduce our study in their article. We agree that radiotherapy is effective to reduce local recurrence rate, although we used preoperative instead of postoperative radiotherapy, which was used in Dr. Kim’s study. Kim et al compared the outcome of patients between the lateral pelvic lymph node dissection (LPLD) group and the postoperative CRT group. Among stage III lower rectal cancers, they successfully demonstrated that the LPLD group showed a 2.2-fold increase in the local recurrence rate as compared with the CRT group. They concluded that patients need adjuvant CRT to reduce local recurrences after LPLD. This study addressed an important issue because so few studies have compared the efficacy of LPLD and radiotherapy. However, to draw the conclusions above, there are major issues to be discussed in this study. The most important point is that the local recurrence rate in the LPLD group is much higher than the previously reported rate by the same Japanese group from Komagome Hospital in Tokyo. This group has been reporting the efficacy of LPLD to reduce the local recurrence rate for years and reported that the 5-year local recurrence rate in stage III lower rectal cancer was only 7.4% in their report published in 2005. However, in Kim’s study, published in 2007, the same group reported that the 5-year local recurrence rate in stage III lower rectal cancer patients was 16.7%. It is unlikely that the local recurrence rate changed from 7.4% to 16.7% during such a short period of time. Is this because of selection biases of patients or due to the different definition of “local recurrence”? This point needs be clarified. The second point relates to postoperative adjuvant chemotherapy. Previous randomized controlled studies and meta-analyses have shown that adjuvant chemotherapy for rectal cancer improves both overall and disease-free survival and reduces local recurrence rates. These studies show that adjuvant chemotherapy significantly affects the postoperative outcome of rectal cancer patients. However, Kim’s study does not refer whatsoever to adjuvant chemotherapy. It is essential to take into account what percentages of patients actually received postoperative adjuvant chemotherapy in each group to compare the postoperative outcome. The third point is that, due to the different definition of “lower rectal cancer,” there seems to be a significant selection bias in “lower rectal cancer patients” between the LPLD and the CRT group. In Kim’s study, lesions located under the peritoneal reflection were classified as “lower rectal caner.” However, in Japan, the definition of “lower rectal cancer” is different. According to “The Japanese Classification of Colorectal Carcinoma Issued by JSCCR,” the tumor location is determined by the “center” and not by the lower edge of the tumor. Therefore, tumors extending below the peritoneal reflection are classified as “upper rectal cancer” if the center of the tumor is above the peritoneal reflection. Furthermore, the indication for LPLD is a “T3 or T4 lesion that extends below the peritoneal reflection” according to the Japanese guideline (JSCCR Guidelines 2005 for the Treatment of Colorectal Cancer). Kim et al showed that 33% of tumors were “upper rectal caner” and 67% “lower rectal cancer” in the LPLD group. However, since LPLD was performed, all lesions (100%) in the LPLD group are considered to extend below the peritoneal reflection and should be classified as “lower rectal cancer” according to Kim’s classification. In other words, 16.7% is not actually the local recurrence rate of “lower rectal caner” in the LPLD group but is the local recurrence rate of “very low rectal cancer” among the LPLD group. This double standard in the definition of “lower rectal cancer” between 2 countries seems to have caused a significant bias in evaluating local recurrence rate of “lower rectal cancer” between 2 groups. In a recent report of the Dutch Trial, tumor location was determined by the distance between the tumor and the anal verge, and the authors demonstrated that tumors located within 5 cm from the anal verge show significantly higher local recurrence rate than those over 5 cm. To eliminate significant selection biases in Kim’s study, they need to compare the local recurrence rate between the LPLD and the CRT group by classifying tumors according to the distance between the tumor and the anal verge. We agree with Kim et al that radiotherapy is useful in improving the outcome of rectal cancer patients. However, these points need to be clarified to conclude that LPLD truly shows a higher local recurrence rate than CRT.
WatanabeT、Tsurita G、Muto T、Sawada T、Sunouchi K、Higuchi Y、Komuro Y、Kanazawa T、Iijima T、Miyaki M、Nakawa H：“下直肠手杖的扩大淋巴结切除术和术前放疗。”Smgeiy。
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