Continuing Debate on Ductal Lavage
A report published in the British medical journal The Lancet has just weighed in on a controversial new technique that may detect breast cancer cells much earlier than mammograms-ductal lavage.
Ductal lavage is a relatively new technique that enables doctors to retrieve and examine cells that line the milk ducts inside the breast. Since breast cancer usually starts in these cells, it is a logical first place to look for suspicious, atypical cells that might eventually become cancerous.
With ductal lavage, the physician places a nursing pump on the breast to draw out fluid and locate the milk ducts. A very tiny tube called a cannula is then inserted into any duct that produces fluid. A small amount of anesthetic and saline is injected, then the breast is massaged to wash the saline around in the ducts. When the saline fluid is drawn back out, cells that line the ducts are extracted as well. These are then examined for atypical, possibly precancerous, features.
While the procedure seems to be complicated, it only takes about 30 minutes. Furthermore, studies have shown that 82 percent of women who have had ductal massage report that it is equal to or less painful than a mammogram.
And yet, ductal lavage may be too new for routine use. "To date, the sensitivity and specificity of these results are unknown," cautions Lillie Shockney, RN, the director of the Johns Hopkins Breast Center in Baltimore, Maryland. "This is why this research must remain 'research' and not be looked upon as ready for use as routine screening. The number of false negatives to date remains unknown."
The Lancet study, written by Dr. Saraswati Sukumar of Johns Hopkins University School of Medicine in Baltimore and colleagues, examined samples of fluid obtained by the ductal lavage technique from 20 women with confirmed breast cancer and 45 healthy women.
The technique was able to detect abnormal cells in 17 of the 20 samples taken from women with breast cancer. It detected cell abnormalities in only 5 of the 45 healthy women.
While not perfect, the technique could be beneficial to women who are considered at high risk for the disease, the authors indicated. This would give them an opportunity to take preventive action before the disease advances.
Researchers have known for years that breast epithelial cells collected by fine needle aspiration or fluid aspiration could be analyzed to search for suspicious or atypical cells that might eventually become cancerous. If such "epithelial atypia" was found, there was a five-fold increase in the risk that breast cancer would eventually develop.
A persistent problem with standard aspiration methods is that no more than a hundred or so cells can be extracted with each sampling. Also, these techniques do not collect cells from deep within the breast. Ductal lavage, on the other hand, is able to collect as many as 40,000 cells per duct, including cells from deep within the breast.
Ductal lavage may soon provide an extremely important new diagnostic tool for women considered at high risk for developing the disease. However, according to Dr. Lorraine Tafra, a breast surgeon at Anne Arundel Medical Center in Annapolis, Maryland, a number of issues need to be addressed before it becomes a standard of care.
For example, she notes, examination of the cells can be difficult, and it is possible that patients may be unnecessarily subjected to a biopsy because of an inaccurate interpretation.
Furthermore, Tafra says, even if an analysis of the fluid shows the presence of abnormal cells, it may be difficult to actually locate the cancer. A new procedure called ductoscopy, which allows for the direct examination of the inside of the ducts, may solve this problem, she adds.
Finally, although ductal lavage appears to be well tolerated, it is uncomfortable enough that most patients would not want to undergo it on a routine basis. Therefore, at least in the short term, it may be most useful for women considered at high risk for the disease.
SOURCES:
The Lancet, April 28, 2001; 357:1335-1336
18th Annual Miami Breast Cancer Conference, Miami, Florida, March 6, 2001
Anne Arundel Medical Center (http://www.aahs.org)
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