Hyperplastic polyps found in the lower part of the colon (*distal colon*) during sigmoidoscopy or colonoscopy do not predict more serious *neoplastic* polyps in the upper part of the colon (*proximal colon*) according to a study reported in the October 2005 [American Journal of Medicine](http://www.amjmed.com/article/PIIS0002934305001737/abstract)
Hyperplastic polyps are benign and do not have the potential to become colorectal cancers. However, adenomas or neoplastic polyps do. Removing adenomatous polyps before they become malignant is one important way to prevent colorectal cancer. Some doctors have thought that finding a hyperplastic polyp in the lower or distal colon might signal the presence of more dangerous neoplastic polyps in the upper or proximal colon. If they found one during a screening sigmoidoscopy, they scheduled the patient for a colonoscopy to look at the entire colon.
During screening colonoscopies, researchers at Virginia Mason Medical Center in Seattle classified patients into three groups: 1) those with hyperplastic polyps only in their distal colons, 2) those with distal adenomas with or without hyperplastic polyps, and 3) those with no distal polyps of either kind.
Of the nearly 2,400 people without symptoms of colorectal cancer who were screened during the study, 18% had at least one neoplastic polyp, 4% had advanced neoplasia where the polyp was larger than 1 centimeter or had other signs that it was approaching malignancy.
However, the percentage of those with neoplastic polyps in their proximal colons was not significantly different whether or not patients had hyperplastic polyps in their distal colons or not. 9% of those without distal hyperplastic polyps had neoplastia in their proximal colons compared to 12% of those who did not have such distal polyps. Two percent of both groups had advanced neoplasia in their proximal colons.
Adenomas in the distal colon *did* signal additional neoplastic adenomas in the proximal colon in about 1/3 of cases.
Otto Lin and his colleagues concluded:
Patients with distal hyperplastic polyps, unlike those with distal adenomas, do not exhibit an increased risk for proximal neoplasia or proximal advanced neoplasia compared to those with no distal polyps. The discovery of hyperplastic polyps on screening sigmoidoscopy should not prompt colonoscopy.
They further emphasize the need to biopsy hyperplastic polyps during sigmoidoscopy to ensure that they were not adenomas.
It will be important for practitioners who perform screening sigmoidoscopies to biopsy distal polyps (as opposed to automatically referring all patients with distal polyps for colonoscopy).
More information about the study is available on [*Medscape*](http://www.medscape.com/viewarticle/516564)