Predicting which colon polyps might transform to cancer

Volume 7, Issue 2, 2018


This discovery would be a major clinical step forward in individualizing patient care.

Photograph of Lisa A. Boardman, M.D.

Lisa A. Boardman, M.D.

Researchers at Mayo Clinic are closer to understanding why one colon polyp transforms to cancer, while another seemingly identical polyp doesn't.

A colon polyp is a small clump of cells that forms on the lining of the colon. While most colon polyps are harmless, some can develop into colon cancer, which can be fatal if found too late.

"The molecular determinants that distinguish normal, benign polyps from those at risk of becoming cancer are unclear," said Lisa A. Boardman, M.D., a Mayo Clinic gastroenterologist in Rochester, Minnesota. "In our paper in the journal Scientific Reports, we asked why one polyp transforms to cancer, while another that is clinically and histologically identical does not"

To answer this question, Dr. Boardman and her colleagues used next-generation sequencing techniques to molecularly characterize and compare colon polyps from Mayo Clinic patients that were associated with cancer with those from patients with polyps that were benign.

Next-generation sequencing is sophisticated DNA and RNA sequencing technology that allows researchers to study biological systems at a level never before possible.

Dr. Boardman and her colleagues found that polyps adjacent to cancerous tissue exhibited distinct genetic alterations from polyps that remained cancer-free.

"By integrating multiple sequencing platforms, we identified a panel of 124 genes that were differentially altered between polyps that were associated with cancer and polyps that did not progress to colorectal cancer," Dr. Boardman said. "These results serve as a foundational study showing that polyps with and without cancer exhibit distinct molecular signatures."

According to Dr. Boardman, the ability to identify molecular features that predict whether a polyp will transform to cancer would be a major clinical step in individualizing the care of patients with polyps. Current national guidelines for polyp surveillance are based on polyp size, number, histology and degree of dysplasia; there are currently no blood-based or tissue-based molecular tests used to tailor surveillance intervals for patients with polyps.

The ability to determine a polyp's risk of progression to cancer could have significant benefits for patients and the health care system, including reducing costs, reducing risks and improving the use of colonoscopy, Dr. Boardman said. "This study is also the first step in our efforts to establish a precancer biobank at Mayo Clinic, which will support future studies on polyps in order to prolong health by preventing premalignancy in the colon," she said.