Researchers have found that ductal lavage was unable to detect cancer or precancerous changes in the breasts of most women undergoing mastectomy for cancer.

The report, which comes from Memorial Sloan Kettering Cancer Center in New York, was published in the journal Cancer (Vol. 98, No. 10: 2170-2176).

The researchers studied 26 women who were undergoing mastectomy for breast cancer. Just before surgery, each underwent ductal lavage. The cells from the lavage were then examined by three pathologists who were looking for cancer or precancerous changes.

Ductal lavage is a technique that has been developed to examine women thought to be at high risk of developing breast cancer, such as women with a strong family history of this disease.

Because breast cancer arises in the cells lining the milk ducts of the breast, doctors have thought that a good way to detect precancerous changes would be to look at these cells. To obtain the duct lining cells, the doctor places a tiny catheter into the duct opening on the nipple. Fluid is injected and then collected to look for the cells. The nipple is numbed with local anesthesia.

Several studies have found that women whose ductal lavage yields abnormal cells are more likely to develop breast cancer than women with normal cells.

But the new study suggests ductal lavage may not be a reliable way to screen women for breast cancer.

The women in the present study had breast cancer and precancerous changes called carcinoma in situ. But, the researchers found abnormal cells in slightly less than half the samples from ductal lavage. Four out of 29 samples, or 14%, were clearly abnormal; 10 samples (34%) showed milder abnormalities. The remaining 15 samples (52%) were completely normal.

So, in over half the women with cancer or precancerous changes in their breasts, the ductal lavage did not find any abnormality. Another problem the researchers encountered was difficulty in diagnosing the lavage samples that had mild abnormalities. In no case did all three pathologists agree that a specimen was mildly abnormal. This means that in some hands, some minor abnormalities might not be diagnosed.

These results led the researchers to conclude that ductal lavage is not a sensitive test. In other words, it doesn't always find existing disease.

The researchers found no cancer cells in any of the specimens, even though 20 of the women had invasive cancer, not just the precancerous carcinoma in situ. All this means that if a woman has a mild abnormality detected through ductal lavage, she could very well have an underlying cancer or precancerous tumor. The researchers say women who have mild abnormalities in ductal lavage samples should be evaluated further, with a clinical exam and mammography, as well as repeat ductal lavage and counseling.

But, the absence of any abnormality is not a guarantee of a normal breast. Thus, ductal lavage should not replace mammography and clinical breast exam, the recommended means of detecting breast cancer.

According to the researchers, just looking at the cells from ductal lavage may not be enough. Not only is it difficult to spot abnormalities, they may be absent much of the time. In the future, if ductal lavage is to be useful in spotting women with cancer or precancerous tumors in their breast, newer techniques for analyzing the cells it collects are needed.

Perhaps, they say, molecular techniques that look for genetic changes or certain cancer-specific markers will be developed to make this test more useful. In spite of its limitation, the researchers feel that ductal lavage will play an important role in looking at breast ductal lining cells and learning how cancer develops.