Small Colorectal Polyps Show Low Malignancy Risk

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.

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- to 9-mm range, wrote Dr. Pickhardt of the department of radiology at the University of Wisconsin-Madison.

They 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.” Also “mucosal-based polyps that were confirmed at colonoscopy but were lost during retrieval, fulgurated, or otherwise ablated were also excluded.”

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,” wrote the authors.

This included two malignant polyps in the 10- to 19-mm group (for a prevalence of 0.9% in this group, out of 216 total polyps), and two malignancies in the 20- to 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- to 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 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.”

Disclosures: 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.

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.

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- to 9-mm range, wrote Dr. Pickhardt of the department of radiology at the University of Wisconsin-Madison.

They 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.” Also “mucosal-based polyps that were confirmed at colonoscopy but were lost during retrieval, fulgurated, or otherwise ablated were also excluded.”

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,” wrote the authors.

This included two malignant polyps in the 10- to 19-mm group (for a prevalence of 0.9% in this group, out of 216 total polyps), and two malignancies in the 20- to 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- to 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 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.”

Disclosures: 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.

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.

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- to 9-mm range, wrote Dr. Pickhardt of the department of radiology at the University of Wisconsin-Madison.

They 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.” Also “mucosal-based polyps that were confirmed at colonoscopy but were lost during retrieval, fulgurated, or otherwise ablated were also excluded.”

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,” wrote the authors.

This included two malignant polyps in the 10- to 19-mm group (for a prevalence of 0.9% in this group, out of 216 total polyps), and two malignancies in the 20- to 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- to 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 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.”

Disclosures: 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.