In a cohort of more than 5,000 patients with a total of 755 colorectal polyps, 100% of malignancies were associated with polyps greater than or equal to 10 mm, Dr. Perry J. Pickhardt and his colleagues reported in an article appearing in the July issue of Clinical Gastroenterology and Hepatology.

Most of the polyps were smaller, however: “6-9 mm lesions represented as much as 61% of all ... lesions,” the authors noted.

“These aggregate results suggest the potential for less aggressive management of some [computed tomographic colonography]–detected lesions,” especially those in the 6-9 mm range, wrote Dr. Pickhardt of the department of radiology at the University of Wisconsin-Madison.

Dr. Pickhardt looked at 5,124 consecutive asymptomatic adults undergoing computed tomography colonography (CTC) between April 2004 and July 2008. Patients’ mean age was 57 years, and 2,792 were women.

“Although individuals were not excluded for a positive family history of colorectal cancer, only 1.7% (89 adults) actually had a positive history according to [American Cancer Society] guidelines,” wrote Dr. Pickhardt (Clin. Gastroenterol. Hepatol. 2010 July [doi:10.1016/j.cgh.2010.03.007]).

Included in the analysis were all CTC-detected colorectal polyps greater than 6 mm that had corresponding endoscopic and/or surgical confirmation, wrote the authors, “including lesions not prospectively identified at CTC but found at subsequent colonoscopy.”

“Mucosal-based polyps that were confirmed at colonoscopy but were lost during retrieval, fulgurated, or otherwise ablated were also excluded,” they added.

A total of 755 lesions greater than or equal to 6 mm were found in 479 patients. This included 464 lesions (61.5%) that were 6-9 mm, 216 lesions (28.6%) that were 10-19 mm, 33 lesions (4.4%) that measured 20-29 mm, and 42 (5.6%) that exceeded 30 mm.

According to Dr. Pickhardt, “In the small polyp group (6-9 mm), the rate of advanced adenomas was 3.9% (18 of 464).” Furthermore, only two polyps in this group were found to exhibit high-grade dysplasia, and none were classified as malignant.

That is in contrast to large polyps – those greater than 10 mm. Here, “the overall rate of advanced adenomas and malignancy was significantly higher compared to the smaller polyp group, at 61.9% (180/291) and 6.9% (20/291), respectively (P less than .001 for both comparisons),” wrote the authors.

This included two malignant polyps in the 10-19 mm group (for a prevalence of 0.9% in this group, out of 216 total polyps), and two malignancies in the 20-29 mm group (for a prevalence of 6.1% in this group, out of 33 total polyps – a significantly higher proportion than the 0.9% prevalence in the 10-19 mm group, with P less than .001).

The remaining 16 malignancies were all found among the group of 42 polyps that measured greater than 30 mm, for a prevalence of 38.1%.

“For CTC-detected masses measuring 3 cm or greater, the risk of cancer clearly outweighs any procedural costs or risks related to its removal,” wrote the authors. However, “For CTC-detected colorectal lesions in the 1-2 cm and 2-3 cm size categories, the need for polypectomy referral has not been questioned in the past, although our findings show that the immediate benefit may not be as great as previously assumed.”

“The guiding principal should be that we carefully balance the risks and benefits to achieve an optimal outcome,” they added.

The authors conceded that the study was limited by the fact that the cohort included “average-risk screening subjects; higher rates of important histology would be expected amongst cohorts at increased risk for colorectal cancer.”

Additionally, they wrote, “Some polyps called at CTC are not found at subsequent colonoscopy,” though these account for “fewer than 10% of all CTC-detected lesions in our experience.”

Dr. Pickhardt and one other author on this study disclosed that they are consultants for Viatronix Inc. and Medicsight PLC, medical and CT imaging companies, and are cofounders of VirtuoCTC LLC, which publishes guidance on CTC.

Copyright (c) 2009 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

Perry J. Pickhardt博士及其同事们在发表于《临床胃肠病与肝脏病学》(Clinical Gastroenterology and Hepatology)7月刊上的一篇文章中报告称，他们在一个包括5,000多例患者共755个结直肠息肉在内的研究队列中，发现所有恶变的息肉都与其直径≥10 mm有密切关系。

 

作者强调说，多数的息肉都很小，然而：“61%的病变大小介于6~9 mm之间。”

 

Wisconsin-Madison大学放射科的Pickhardt博士写道：“这些汇总结果表明，经‘计算机断层扫描结肠成像术’检测到的病变恶性程度较低，”尤其对6~9 mm间的病变来说更是如此。

 

2004年4月至2008年7月，Pickhardt博士对5,124例连续无症状成年患者进行了计算机断层扫描结肠成像检查。患者的平均年龄为57岁，其中2,792例为女性患者。

 

Pickhardt博士(Clin. Gastroenterol. Hepatol. 2010 July [doi:10.1016/j.cgh.2010.03.007])写道：“尽管具有结直肠癌家族史的患者并未被排除在外，按照‘美国癌症协会’的指南标准，本组患者中仅有1.7% (89例成人)具有阳性家族史。”

 

入组该研究的病变为经CTC检出结直肠息肉且息肉＞6 mm者，并得到了内镜检查或外科手术的验证。作者在文章中写道：“研究中也包括了那些最初并没有经CTC检出、而是由接下来的结肠镜检查发现的病变。”

 

他们补充说：“经结肠镜确诊但在恢复过程中失访以及经电灼或其他消融方式切除黏膜息肉者被排除在本研究之外。”

 

479例患者中，共发现≥6 mm的病变755个。其中包括6~9 mm的病变464个(61.5%)，10~19 mm的病变216个(28.6%)，20~29 mm的病变33个(4.4%)，而＞30 mm的病变为42个(5.6%)。

 

Pickhardt博士指出，“在小息肉组(6~9 mm)中，晚期腺瘤占3.9% (18/464)。”此外，在这组患者中，仅有2个具有高度不典型增生，无恶性肿瘤。

 

这项研究中，大息肉组——直径＞10 mm者的结果完全相反，作者写道：“晚期腺瘤和恶性病变的总发生率明显高于小息肉组，晚期腺瘤和恶性病变分别占61.9% (180/291) 和 6.9% (20/291)(两组比较P <0.001)。”

 

在10~19 mm息肉组中，发现2个恶性息肉病变(该组共216个，其发生率为0.9%)。在20~29 mm息肉组中，发现2个恶性息肉病变(该组共33个，其发生率为6.1%，明显高于10~19 mm息肉组中0.9%的发生率，P <0.001)。

 

其余的16个恶性病变均见于＞30 mm息肉(42个)组，其发生率为38.1%。

 

作者写道：“对于经CTC检出的≥3 cm的肿物，其癌变的风险明显超过任何手术成本或将其切除所带来的相关风险。”然而，“对于经CTC检出的1~2 cm 和 2~3 cm大小的肿物，过去对因息肉切除术而转诊的措施没有任何争议，然而我们的研究发现其短期收益也许没有我们之前预想的那么好。”

 

他们还补充道：“主要原则应该是仔细权衡治疗的风险与效益，以期达到最佳治疗效果。”

 

作者承认此项研究存在一定局限性，如研究队列包括“平均风险筛查个体；结直肠癌风险增加的患者群中预期组织学重要病变的发生率较高。”

 

而且他们还写道：“一些经CTC检出的病变在随后的结直肠镜检中并没有被发现，”尽管如此，“根据我们的经验，占所有经CTC检出病变的10%以下。”

 

Pickhardt博士和另一位作者表示他们是Viatronix公司和Medicsight PLC公司(二者均为医疗和CT影像公司)的顾问，是VirtuoCTC LLC的共同创始人，VirtuoCTC LLC发布了有关CTC的应用指南。

 

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