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October 30, 2006 (拉斯维加斯) -- 根据研究团队在美国肠胃科学会(ACG)第71届年会中所发表的研究发现，一开始大肠镜检没有肿瘤的人，在五年追踪期间，鲜少会有任何的良性或恶性损伤。
根据主要研究者，印第安那大学医学院医学教授Thomas F. Imperiale医师所述，这些发现颇令肠胃科医师感到鼓舞，这些医师们过去认为没有足够文献决定大肠镜检的复检期间间隔应该多长。
Imperiale医师在发表时表示，在一开始筛检无肿瘤后的五年大肠直肠癌风险相当低，进行性腺瘤的风险也低，不过在男性高过女性；这些发现显示医师可以在安全的前提下，将大肠镜检复检安排在初次检查后十年，一如目前ACG所建议的。
Imperiale医师和同事希望建立初次大肠镜检阴性者的大肠直肠肿瘤风险率，为了达到目标，他们从以劳工基础的大肠镜筛检计划资料库中，鉴别哪些在初次镜检没有肿瘤，和哪些在五年后再度做镜检者；此一研究计划从1995年9月到2000年6月。
研究者定义末端肠道为降结肠、乙状结肠和直肠，他们根据最恶化的损伤将每一肠段分类；分类如下：(1)无息肉 (2) 增生性息肉 (3) 管状腺瘤< 1 cm (4) 进行性腺瘤，指管状腺瘤> 1 cm，绒毛组织学检出有息肉，或高度发育异常 (5)癌症。
这2,436 位在初次镜检没有腺瘤者之中，有1,256位 (51.6%)回来做大肠镜复检，这些复检者的平均年纪是 54.7岁，未复检者为 58.3岁(P < .001)；不过，其他的人口统计学变项如种族、性别和收入就有差异；复检者之中，有57%是男性，未复检者之中，男性有53%。
检查的医师在复检者之中没有发现癌症，筛检组之中，201位参与者(16%)有至少一个腺瘤，这之中有 34%仅有末端损伤，40%仅有近端损伤，27%有末端损伤也有近端损伤，这类的损伤在一开始就有息肉的病患是常见的，相对风险(RR)是 1.62，一开始有息肉者和无息肉者的年纪相似，有息肉者平均 57.6岁，无息肉者平均 56.6岁。
Imperiale医师指出，有15位(1.2%)出现进行性腺瘤，其中2%一开始有息肉，1%是一开始无息肉，此一差距并无统计上的显著意义。
追踪期间男性的腺瘤比率将近是女性的两倍，男性的比率是20.1%，女性是10.7% (RR = 1.88)，男性也较可能有进行性腺瘤，男性的比率是1.7%，女性是0.55% (RR = 3.07)；初检时，388位年纪在60岁以下的妇女之中，有1 位女性(0.26%)出现进行性腺瘤 (95% CI, 0.01% - 1.43%)，初检时年纪在55岁以下的634位男女之中，7位 (1.1%)出现进行性腺瘤(95% CI, 0.45% - 2.26%)。
Phillip E. Jaffe医师在电话访问中表示，我们可以因此对建议初次镜检后一般风险者在10年后复检的国家规范感到更欣慰，Jaffe医师未参与此研究，他是耶鲁大学医学院的医学副教授，且在Hamden执业，他以ACG公关委员会的一员发表谈话。.
Jaffe医师表示，这些资料支持此项建议，显示我们对此问题并非一事无成，而且我们也有了正面的冲击；一旦你有了阴性的镜检结果，可对下次的镜检将一样是阴性感到舒坦；扩大验证肠胃科医师所执行的此项步骤中，镜检结果正常者在五年后长出某些东西的机会极低 。
Jaffe 医师补充道，事实是在合并学术和私人开业医师的基础下进行大肠镜检是令人鼓舞的，这告诉我们可以藉由筛检和十年后的复检进行正确的事情。
ACG 71届年会：摘要12。发表于 October 23, 2006。
Neoplastic Lesions Are Rare 5 Years After Negative Baseline Colonoscopy
By Paula Moyer, MA
Medscape Medical News
October 30, 2006 (Las Vegas) — People who have no neoplasms on a baseline colonoscopy rarely have any such lesions, benign or malignant, at the 5-year follow-up, according to a team of investigators who presented their findings here at the 71st annual meeting of the American College of Gastroenterology (ACG).
The findings should be reassuring to gastroenterologists, who have been concerned about the paucity of literature to determine the appropriate interval between screening colonoscopies, according to principal investigator Thomas F. Imperiale, MD, a professor of medicine at Indiana University School of Medicine in Indianapolis.
"The 5-year risk of colorectal cancer is extremely low after a screening exam which found no neoplasms," Dr. Imperiale said during his presentation. "The risk of an advanced adenoma is also low, though higher in men than in women." The findings show that physicians can safely schedule repeat colonoscopies 10 years after the baseline examination, as currently recommended by the ACG.
Dr. Imperiale and colleagues wanted to identify the risk of colorectal neoplasia in people whose baseline screening colonoscopy was completely negative of such findings. To do so, they identified people in a database from an employer-based screening colonoscopy program who had had no neoplasms in the baseline colonoscopy and who returned for a 5-year repeat colonoscopy. The colonoscopies had been conducted from September 1995 to June 2000.
The investigators defined the distal bowel as the descending colon, sigmoid colon, and rectum, and they categorized each bowel segment according to the most advanced lesion present. The classifications were as follows: (1) no polyps, (2) hyperplastic polyp(s), (3) tubular adenoma < 1 cm; (4) advanced adenoma(s), defined as a tubular adenoma > 1 cm, a polyp with villous histology, or high-grade dysplasia; or (5) cancer.
Of the 2436 participants who had no adenomas at baseline, 1256 (51.6%) returned for a repeat colonoscopy. Those who returned for repeat screening were an average of 54.7 years old compared with an average age of 58.3 years for those who did not return (P < .001). However, they were comparable in all other demographic variables, such as race, sex, and income. Within these groups, 57% of the repeats were men compared with 53% of the nonrepeats.
The examining physicians found no cancers in the rescreened group. Within the screened group, 201 participants (16%) had at least 1 adenoma, and of these, 34% had a distal lesion only and 40% had a proximal lesion only, while 27% had both proximal and distal lesions. Such lesions were more common in patients with a baseline polyp, for a relative risk (RR) of 1.62. Those with polyps and no polyps at baseline were similar in age, averaging 57.6 years for those with baseline polyps and 56.6 years for those without baseline polyps.
Advanced adenomas were present in 15 people (1.2%), and of these, 2% had had baseline polyps and 1% had not, a difference that was not statistically significant, according to Dr. Imperiale.
Men were nearly twice as likely to have an adenoma at follow-up, with rates of 20.1% for men and 10.7% for women (RR = 1.88). Men were also more likely to have an advanced adenoma, with such lesions occurring in 1.7% of men and 0.55% of women (RR = 3.07). Of the 388 women who were younger than 60 years at baseline, 1 woman (0.26%) had an advanced adenoma (95% confidence interval [CI], 0.01% - 1.43%). Of the 634 men and women who were younger than 55 years at baseline, 7 (1.1%) developed an advanced adenoma (95% CI, 0.45% - 2.26%).
"We would like to feel more comfortable with the national guidelines, which recommend a repeat screening at 10 years after the initial colonoscopy for patients with average risk," said Phillip E. Jaffe, MD, in a phone interview. Dr. Jaffe, who was not involved in the study, is an associate professor of medicine at Yale University School of Medicine in New Haven, Connecticut, and he practices in Hamden, Connecticut. He spoke as a member of the ACG public relations committee.
"These data support this recommendation by showing that we're not doing anything to miss problems, but we're also having a positive impact," Dr.Jaffe said. "Once you've had a negative colonoscopy, you can be comfortable that future colonoscopies will be negative. Among board-certified gastroenterologists performing the procedure, the odds of finding something at 5 years after a normal colonoscopy is very small."
The fact that the colonoscopies were performed by "a combination of academics and private practitioners" was very encouraging, Dr. Jaffe added. "This tells us that we're doing the right thing by having screening performed and that the 10-year wait time is appropriate."
ACG 71st Annual Meeting: Abstract 12. Presented October 23, 2006.