10%的肿瘤性息肉可能未被完全切除

美国White River Junction退伍军人医疗中心的Heiko Pohl博士及其同事在《胃肠病学》(Gastroenterology)1月刊上报告称，在1,427例接受结肠镜检查的病例系列中，大约10%的直径介于5~20 mm的肿瘤性息肉未被完全切除。

在这项名为“完全腺瘤切除(CARE)”的研究中，Pohl博士及其同事对在这两家大型学术性医疗机构接受门诊结肠镜检查的年龄介于40~85岁的所有成年患者病例进行了分析，所有患者均无炎症性肠病病史，均不存在凝血功能障碍，并且检查示其至少存在1个直径介于5~20 mm的息肉。

参与这项研究的经过学会认证的胃肠病医生采用标准的结肠镜和息肉切除器以及标准的电刀工具来摘除病灶。胃肠病医生先测量并切除息肉，然后肉眼观察切缘，钳取切缘的活检样本，最后确认息肉已完全切除。医生还记录了整个切除操作是容易、比较困难还是困难。研究方案没有要求使用窄带成像或者氩离子血浆凝固术，但也允许各胃肠病医生视情况酌情使用。

由一名胃肠病理学专家独立分析所有残余腺瘤组织的活检样本并对息肉进行分类。共有346个(83%)息肉为肿瘤性。其中68%被归为管状、管状绒毛或者绒毛腺瘤。12%具有锯齿状组织学形态，包括42个 (10%)无蒂锯齿状腺瘤/息肉。

这名病理学专家发现，总的来看，大约有10%的肿瘤性息肉未被完全切除。大息肉(10~20 mm)不完全切除的几率比小息肉(5~9 mm)高1倍以上(17.3% vs. 6.8%)。无蒂锯齿状腺瘤/息肉不完全切除的几率比其他类型高3倍(31% vs. 7%)。因此，将近一半(48%)的无蒂锯齿状大腺瘤/息肉都未被完全切除。

Pohl博士及其同事写道：“由于腺瘤大小与晚期组织学病变的几率增加以及近期转变为癌症的风险增加相关，因此不完全切除体积较大的肿瘤性息肉是一个令人担忧的问题。”

研究没有发现与不完全切除相关的其他因素，包括切除操作被视为困难而非容易，息肉必须分块切除而非一次性切除，息肉位于右侧或左侧结肠以及息肉形态为扁平型或其他类型。

这346个肿瘤性息肉的切缘活检结果显示，35例患者的结肠内遗留了部分肿瘤性组织，共涉及这两家医疗中心的11名颇有经验的胃肠病医生。对于不同的内镜医生，不完全切除率差异很大，在6.5%~22.7%之间不等。而且，这些医生都知道他们在参与这项研究，可能在完成完全切除方面已经比平时更加谨慎。

Pohl博士及其同事说：“上述数据提示，在日常临床实践中息肉未被完全切除的现象可能比较常见，这可能与患者未来发生癌变有关。”研究结果还表明，目前结肠镜质量评价标准多以检出率为主，如今看来还应考虑切除的完全性。研究者指出：“高质量的有效的结肠镜操作不仅需要准确发现肿瘤性息肉，还需要完全切除这些息肉。”(Gastroenterology 2013;144:74-80)。

研究者说，到目前为止，“关于息肉切除是否充分的直接信息出乎意料的少。通常认为只要切除后肉眼没有发现任何明显的息肉组织，即可视为完全切除。采用带电刀的息肉切除器可能有助于进一步破坏残留的息肉组织”，但是否真能达到这样的效果，这还从未经过研究的证实。

研究者写道：“上述研究结果对息肉切除术的质量提出了质疑，呼吁大家需进一步完善肿瘤性息肉的切除，尤其是体积较大的息肉和无蒂锯齿状腺瘤/息肉。”此外，可能需要采用特殊的成像技术来评估息肉边缘，这一点应引起更多的关注。切除前勾画并标注息肉边缘也可能有助于提高息肉的完全切除率。对于部分病例，切除后辅以切缘消融处理可能也会有所帮助。

作者声明无相关经济利益冲突。

相关评论：需要标准化的操作技术

Charles J. Kahi博士认为，结肠镜技术可以在很大程度上预防结直肠癌(CRC)，但其有效性取决于操作质量，这便和施术医生有关。已有研究表明，对于近端CRC病例，如果内镜医生的腺瘤检出率和盲肠插管率很高，息肉切除率也很高，那么患者接受结肠镜后保护其免于CRC的效果也最好。施术医生的专业性也与结肠镜后CRC风险相关，胃肠病专科医生相比其他专科医生能为患者提供更好的保护。

结肠镜下息肉切除术是有效预防CRC的基础；但相比其他结肠镜质量参数，目前对于息肉切除技术和质量的研究却很匮乏，尽管已知美国内镜医生的息肉切除技术相差很大，每4例间期CRC中就有1例可能是因息肉切除不足所致。Pohl博士及其同事开展的这项CARE研究是对现有文献的一次重要补充：以直径介于5~20 mm的无蒂息肉为研究对象，这类息肉很常见，而且与一般性内镜实践也最相关；研究提供了有关息肉不完全切除的流行率及其相关因素的信息。

CARE研究表明，息肉不完全切除可能是一种比较常见的现象，不但结肠镜检出肿瘤取决于施术医生，切除完全与否也取决于施术医生。尚需开展更多的研究以确定并标准化实现息肉完全切除所需的技术要领，从而降低施术医生之间的变异度并优化结肠镜下息肉切除的质量。

Kahi博士是美国Richard L. Roudebush退伍军人医疗中心消化科主任。他声明无相关经济利益冲突。

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By: MARY ANN MOON, Internal Medicine News Digital Network

Approximately 10% of neoplastic polyps that were 5-20 mm in size were not completely resected in a series of 1,427 patients undergoing colonoscopy, Dr. Heiko Pohl and his colleagues reported in the January issue of Gastroenterology.

Biopsies from the resection margins of 346 neoplastic polyps showed that some neoplastic tissue had been left behind in 35 cases in the Complete Adenoma Resection (CARE) study, which involved 11 experienced gastroenterologists practicing at two large academic medical centers.

The rate of incomplete resections varied widely across the different endoscopists, from 6.5% to 22.7%. Moreover, these physicians were aware that they were participating in the study and may have been more careful than usual to accomplish complete resection.

"Our study provides plausible data that incomplete polyp resection in daily clinical practice is relatively common and may contribute to future interval cancers," said Dr. Pohl of White River Junction (Vt.) VA Medical Center and Dartmouth-Hitchcock Medical Center, Lebanon, N.H., and his associates.

The findings also suggest that quality measures for colonoscopy, which to date have focused primarily on detection rates, should now include the completeness of the resection. "The performance of high-quality and effective colonoscopy not only requires expertise in finding neoplastic polyps, but also removing them," the investigators noted (Gastroenterology 2013;144:74-80).

Until now, there has been "surprisingly little direct information on the adequacy of polyp resection. It is generally assumed that resection is complete if no apparent polyp tissue is visible after resection. Using a snare with electrocautery should further destroy any remaining polyp tissue," but whether it actually does so has never been tested, they said.

Dr. Pohl and his colleagues reviewed the cases of all adults aged 40-85 years who presented for outpatient colonoscopy at the two study centers, had no history of inflammatory bowel disease, had no coagulopathies, and were found to have at least one polyp that was 5-20 mm in size.

The board-certified gastroenterologists participating in the study used standard colonoscopes and polypectomy snares to remove the lesions, along with standard electrocautery equipment. The polyps were measured and resected, then the gastroenterologists inspected the resection margins macroscopically, obtained forceps biopsies of the resection margins, and attested that the removal was complete.

They also recorded whether the resection had been easy, moderately difficult, or difficult.

The use of narrow band imaging, chromoendoscopy, or argon plasma coagulation was not required by the study protocol but was allowed at the discretion of each gastroenterologist.

An expert gastrointestinal pathologist independently examined all the biopsies for residual adenomatous tissue, as well as to classify the polyps.

A total of 346 polyps (83%) were neoplastic.

Sixty-eight percent of these polyps were classified as tubular, tubulovillous, or villous adenomas. Twelve percent had a serrated histology, including 42 (10%) that were sessile serrated adenomas/polyps.

The expert reviewer found that overall, 10% of the neoplastic polyps were incompletely resected.

Large (10- to 20-mm) growths were more than twice as likely to be incompletely resected (17.3%) than were small (5- to 9-mm) growths (6.8%). Sessile serrated adenomas/polyps were four times more likely than other types to be incompletely resected (31% vs. 7%).

As a result, almost half (48%) of all large sessile serrated adenomas/polyps were incompletely resected.

"Because adenoma size is associated with both a higher prevalence of advanced histology and greater near-term risk of transition to cancer, incomplete resection of large neoplastic polyps is concerning," Dr. Pohl and his colleagues wrote.

No other factors were found to correspond with incomplete removal, including whether the resection was rated as difficult rather than easy, whether the polyps had to be removed piecemeal rather than all at once, whether the polyps were located in the right or left colon, and whether they had flat or other morphology.

"Our results raise questions regarding the quality of polyp resection and call for efforts to improve resection of neoplastic polyps, especially large polyps and sessile serrated adenomas/polyps," the researchers wrote.

In particular, increased attention to the polyp margin using special imaging may be warranted. Outlining and marking the margin before resection also might improve the completeness of the removal. And in some cases, adjunctive ablation of the margins after resection may be useful, they added.

The authors reported no relevant financial conflicts.

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Standardized Techniques Needed

Colonoscopy can achieve significant levels of protection against colorectal cancer (CRC), but its effectiveness depends on performance quality, which is operator dependent, according to Dr. Charles J. Kahi.

Studies have shown that patients are best protected against CRC when they undergo colonoscopy by endoscopists with high adenoma detection and cecal intubation rates, and high rates of polypectomy in the case of proximal CRC. Provider specialty also is associated with the risk of postcolonoscopy CRC, with gastroenterologists achieving higher levels of protection than other specialists.

Colonoscopic polypectomy is a cornerstone of effective CRC prevention; however, polypectomy technique and quality have been understudied, compared with other colonoscopy quality metrics, despite the known variability in polypectomy technique among U.S. endoscopists, and the estimation that one in every four interval CRCs may be due to inadequate polypectomy. The CARE study by Dr. Pohl and his colleagues is an important addition to the literature: It is focused on nonpedunculated polyps 5-20 mm in size, which are commonly detected and are most relevant to general endoscopy practice, and it provides information regarding the prevalence and factors associated with incomplete polypectomy.

The CARE study shows that incomplete polypectomy is likely a common phenomenon, and that colonoscopy’s operator dependency with regard to neoplasm detection also applies to resection. Additional study is warranted to determine and standardize the technique components required to achieve complete polypectomy, and thus decrease operator variability and optimize colonoscopic polypectomy quality.

Dr. Kahi is chief of the GI section at the Richard L. Roudebush VA Medical Center, Indianapolis. He said he had no relevant financial disclosures.