The presence of large, serrated polyps was associated with a greater risk of colorectal cancer than any other factor, including age, sex, size of adenomas, and number of adenomas, reported Dr. Sakiko Hiraoka and colleagues in an article appearing in the November issue of Gastroenterology.

Moreover, the cancers in patients with large serrated polyps were more than twice as likely to be proximal as opposed to distal, the authors reported (Gastroenterology 2010 November [doi:10.1053/j.gastro.2010.07.011]).

Dr. Hiraoka of the department of gastroenterology and hepatology at Okayama University, Japan, and colleagues performed a database study including 10,199 patients who had their first colonoscopy at Dr. Hiraoka’s institution or at 1 of 14 affiliated hospitals between June 2005 and May 2008.

Patients had to have no prior history of resection, no prior diagnosis of inflammatory bowel disease, and no familial adenomatous polyposis or hereditary nonpolyposis colorectal cancer.

The mean age was 58.9 years, with 51.5% being male. Overall, 8.6% of the 10,199 patients were having a standard screening colonoscopy, while 41.5% underwent colonoscopy secondary to a positive fecal occult blood test. Another 20.6% had the colonoscopy because of abdominal symptoms, 13.2% due to rectal bleeding, and 2.4% because of anemia or another reason.

In the cohort, there were a total of 1,573 patients (15.4%) with advanced neoplasia, including 708 (6.9%) with colorectal cancer and 140 (1.4%) with large serrated polyps.

Dr. Hiraoka and colleagues found that out of several known risk factors for colorectal cancer, the presence of large serrated polyps carried the greatest risk, with an odds ratio of 3.34 (P less than .0001). The next-highest risk among the variables studied was age of 65 years or older (OR 2.63; P less than .0001).

Having four or more adenomas on colonoscopy carried an OR of 1.65 (P less than .01), and having an adenoma greater than 10 mm carried an OR of 1.56 (P less than .001).

Male gender did not carry any significant increased risk in this analysis.

The authors then looked at the predictors of advanced neoplasia and cancer according to location, “since clinical and biological differences have been shown recently to exist between colorectal neoplasia in the proximal and distal colon,” they wrote.

Dr. Hiraoka and colleagues found that large serrated polyps were more than twice as likely to develop into proximal colon cancer than into distal colorectal cancer (OR for proximal cancer, 4.79; P less than .0001; OR for distal colorectal cancer, 2.23; P less than .01).

The correlation between serrated polyps and proximal cancer may be a manifestation of common molecular backgrounds between them, including BRAFmutation, according to the authors.

However, it does not follow that large serrated polyps necessarily progress into colorectal cancers themselves. “In fact, CRCs which develop in [hyperplastic polyposis syndrome] patients are largely microsatellite stable rather than [microsatellite instability-high] MSI-H, suggesting that serrated polyps do not always progress into MSI-H cancer,” they commented.

The authors noted that one advantage of their study was the “relatively large” proportion of patients with colorectal neoplasia.

However, they noted that their study did not involve correlating neoplasia with the specific type of serrated polyp (including hyperplastic, sessile serrated adenoma, traditional serrated adenoma, and mixed serrated polyp), which was a limitation.

Dr. Hiraoka and colleagues disclosed no conflicts of interest related to this study.

Copyright (c) 2010 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

日本冈山大学胃肠病学和肝脏病学系Sakiko Hiraoka博士及其同事在11月出版的《胃肠病学》杂志上发表文章称，较大锯齿状息肉与结直肠癌较高风险的相关性大于包括年龄、性别、腺瘤大小以及腺瘤数目在内的其他任一因素；较大锯齿状息肉患者罹患近端结肠癌症的可能性是远端结直肠癌症的2倍多(Gastroenterology 2010 November   [doi:10.1053/j.gastro.2010.07.011])。

 

研究者对2005年6月～2008年5月期间首次接受结肠镜检查的10,199例患者的数据资料进行分析研究。患者无切除手术史、无肠炎以及无家族性腺瘤性息肉病或遗传性非息肉性结直肠癌，平均年龄为58.9岁，51.5%为男性。标准结肠镜筛查者占8.6%，粪便隐血试验阳性后接受结肠镜检查者占41.5%，因腹部症状、直肠出血和贫血或其他原因接受结肠镜检查者分别为20.6%、13.2%和2.4%。1,573例(15.4%)患有进展期肿瘤，包括708例(6.9%)结直肠癌和140例 (1.4%)较大锯齿状息肉。

 

变量分析研究发现，在数个已知的结直肠癌风险因素中，较大锯齿状息肉风险最大(OR为3.34， P <0001)，其次是年龄为65岁或以上(OR 为2.63，P<0.0001)，4个或以上腺瘤以及大于10mm腺瘤的OR分别为1.65(P<0.01)和1.56(P<0.001)，而男性未见显著性风险增加。此外，较大锯齿状息肉发展为近端结肠癌的风险是远端结直肠癌的2倍多(前者OR为4.79，P <0 .0001；后者OR为2.23，P <0.01)。

 

研究者无利益冲突声明。

 

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