NEW YORK, Apr 27 (Reuters Health) - An experimental technique may one day be used to detect breast tumors that are too small to show up on a mammogram, researchers report.

The procedure, known as ductal lavage, involves "washing" breast milk ducts with saline and examining cells for signs of precancerous or cancerous changes. Dr. Saraswati Sukumar of Johns Hopkins University School of Medicine in Baltimore, Maryland, who led the new research, explained that breast cancer most often begins in the cells lining the milk ducts.

If tumors are present in the breast, they will shed cells that can be detected in the fluid washed through the ducts, she said in an interview with Reuters Health.

Sukumar's team examined samples of ductal fluid from women with breast cancer and women without the disease to detect signs of a process called methylation. The presence of markers for this process suggests that a woman has breast cancer or precancerous breast cells, according to Sukumar.

Markers of methylation were present in the ductal fluid of 17 of 20 women with breast tumors and in two out of seven women with cancer limited to the breast duct, the researchers report in the April 28th issue of The Lancet. In contrast, Sukumar and her colleagues detected signs of methylation in only 5 out of 45 cancer-free women.

Ductal lavage is a "very sensitive, relatively simple test," according to Sukumar. The procedure, which takes about half an hour to perform, eventually may become a part of routine breast cancer screening, she said.

It may allow doctors to "pick out cancer cells very early in the game" when cancer cells are too small to be seen on a mammogram. The screen may also benefit women with very dense breast tissue, which makes mammograms difficult to read.

Ductal lavage "would be a great tool for assessing risk," according to Sukumar. If the screen detected precancerous cells, a woman could be followed more closely to see whether she developed cancer, Sukumar explained. Based on the test, women might be treated with drugs shown to prevent breast cancer.

Several groups of researchers are working with the new technique, but Sukumar cautioned that the ability of ductal lavage to detect cancer must be confirmed in much larger studies.

"It's very promising, but it really needs to be tested out in a large number of women," she said.

From ReutersHealth