Isolated Colon Cells Make Basis for Cancer Screening

By Judy McBride
June 4, 1998

Live colon cells isolated from stool samples may soon give physicians a reliable early warning system for colorectal cancer, according to an editorial by two Maryland scientists in the June issue of Gastroenterology.

Colon cancer causes about 14 percent of all cancer-related deaths in the U.S. It begins as abnormal growths, or polyps, three to five years before a malignancy appears. A noninvasive screening technique could give physicians ample time to remove polyps before they turn cancerous and patients opportunity to correct dietary habits that may contribute.

The current noninvasive screening method--which checks for blood in fecal smears--is plagued with false positives and false negatives. And a true positive reading means the tumor is fairly advanced. Instead, the Gastroenterologyeditorial discusses the potential for an early warning method based on subtle changes in the genes and surface proteins of isolated colon cells.

Agricultural Research Service scientist Padmanabhan P. Nair at the Beltsville (Md.) Human Nutrition Research Center developed the method for isolating colon cells from the stool. Nair and Sudhir K. Dutta, director of gastroenterology at Sinai Hospital of Baltimore, then found that CD44--the tell-tale marker reported on other types of cancer cells--also appears on the surface of isolated colon cells. They've also detected mutated genes in these cells, indicating malignancy.

Dutta and Nair co-authored the Gastroenterology editorial. It accompanies a report by Japanese researchers who isolated colon cells and found variants of the CD44 marker that might make sensitive indicators of precancerous conditions. In the February issue of Gastroenterology, British researchers reported a strong correlation between the amount of DNA in isolated colon cells and the presence of tumors. That's because rapidly dividing cells contain more DNA.

Dutta and Nair envision that, in five years, stool samples will routinely be analyzed for an array of tell-tale markers and gene mutations. Their technique is already one of the first molecular biology assays to be evaluated in a clinical setting, the researchers report.

Scientific contact: Padmanabhan P. Nair, Beltsville Human Nutrition Research Center, Beltsville, MD 20705, phone (301) 504-8145, fax (301)504-8077, nair@bhnrc.arsusda.gov; Sudhir K. Dutta, Division of Gastroenterology, Sinai Hospital of Baltimore, Baltimore, MD 21215, phone (410) 601-5392, fax 410 601 5757, sdutta@sinai-balt.com.