A new test, which collects and analyzes cells from the milk ducts of breasts, is not an effective method for detecting breast cancer in high-risk women, according to findings from one of the most rigorous studies ever conducted evaluating the procedure known as ductal lavage (search).
Dubbed by some as the "Pap smear for the breast," ductal lavage involves flushing fluid from milk-producing ducts in the breast. It is not a screening tool and does not replace mammography (search). The procedure, however, may help identify cancerous or precancerous cells.
The theory is that since the vast majority of breast cancers develop in the cells that line the milk ducts, this would be one of the first places that these abnormal or atypical cells would appear. Some studies have shown that atypical cells increase the risk of breast cancer development. Finding abnormal cells in a lavage sample therefore gives information about a women's risk for breast cancer.
While ductal lavage is still seen by many as a useful tool for assessing individual breast cancer risk among high-risk women, it is clearly not useful for identifying early breast cancers researcher Seema Khan, MD, of Northwestern Memorial Hospital tells WebMD.
"There was a fair amount of enthusiasm early on that this might be a sensitive cancer detection tool, but the clinical studies have not shown this to be the case," Khan says. "It is now clear that the sensitivity of this test is not very good."
Khan and colleagues from the Lynn Sage Comprehensive Breast Center and Northwestern Memorial Hospital, performed ductal lavage on 32 women with known breast cancer prior to mastectomy and on another seven high-risk women having one or more breasts removed to prevent the cancer.
The findings on the lavaged specimen were later compared directly with cells from breast tissue following surgery.
Ductal lavage was able to detect cancerous cells in only about half of the cancerous breasts. The researchers say that this may be due to the fact that ducts with cancer cells failed to yield enough fluid for evaluation, arguing against the widely held premise that fluid-yielding ducts are more likely to contain cancerous cells.
The study is published in the Oct. 20 issue of the Journal of the National Cancer Institute.
While experts widely agree that the evidence does not support the use of ductal lavage as a procedure to diagnose breast cancer, experts disagree on its present value for assessing breast cancer risk. Breast cancer specialist Freya Schnabel, MD, of Columbia University Medical Center, says she performs the test in high-risk patients who want as much information as they can get about their individual risk.
"High-risk women in this day and age have a lot of options in front of them," she tells WebMD. "They can undergo intensive surveillance, take (the preventive therapy) tamoxifen, or take part in a prevention study. This test can help them make better decisions about which option is best for them."
But Carol Fabian, MD, of the University of Kansas Medical Center, says she does not recommend ductal lavage to her high-risk patients because it is not clear that the procedure offers advantages over more established nipple aspiration procedures.
Ductal lavage yields more cells from the area of the breast in which cancers typically begin than the other methods, leading to the belief that it is more sensitive for identifying atypical cells. But the studies needed to show this have not been completed.
"With the other procedures I can tell a woman exactly what the findings mean because the studies have been done," she tells WebMD. "I can say to a woman with atypical cells found with fine needle aspiration that her risk of developing a noninvasive or invasive cancer is between 3 percent and 5 percent a year. I can't give her a solid figure with ductal lavage because we don't know it." That is because not finding atypical cells does not necessarily reflect a reduced risk; it may simply reflect a lack of cells being flushed out by the procedure.
Recent studies show that combining magnetic resonance imaging (MRI) with mammography may be an important advance for detecting breast cancers early in women at high risk. Fabian says she now recommends the dual-imaging approach to her high-risk patients, with each test being done annually, six months apart.
"In my mind this is the best way to detect cancer early in patients at high risk," she says.
By Salynn Boyles, reviewed by Brunilda Nazario, MD
SOURCES: Khan et al., Journal of the National Cancer Institute, vol 96: pp 1510-1517. Seema A. Khan, MD, department of surgery, Lynn Sage Comprehensive Breast Center, Chicago. Carol J. Fabian, MD, department of internal medicine, University of Kansas Medical Center, Kansas City, KS. Freya R. Schnabel, MD, FACS, chief of breast surgery section, Columbia University Medical Center; associate professor of clinical surgery, Columbia University College of Physicians and Surgeons.