SAN ANTONIODuctal lavage was associated with a high false-negative rate in a recent study, according to Seema A. Khan, MD, associate professor of surgical oncology, Lynn Sage Breast Center at Northwestern University. Moreover, about half of the non-fluid-yielding ducts examined in the study contained cancer, she said at the 25th Annual San Antonio Breast Cancer symposium (abstract 25).
"Ductal lavage has aroused a lot of enthusiasm as a possible method of breast cancer detection, but before we can provide this as a tool for detecting breast cancer, several questions must be answered," Dr. Khan said. "These include an understanding of the histologic correlates of our cytologic findings from lavage, the sensitivity and specificity of ductal lavage as a detection method, and the frequency of disease in non-fluid-yielding ducts."
The study attempted to answer some of these questions by performing ductal lavage on women scheduled for mastectomy. Patients underwent ductal lavage with saline in the operating room before surgery. If the cytological sample was evaluable for diagnosis, the lavaged duct was injected with a combination of gelatin dye and Omnipaque. If more than one duct was lavaged, different colors of gelatin were used. The breast was then x-rayed to confirm instillation of the dye through the ductal tree. Breast tissue was chilled and sliced at 2- to 3-mm intervals to yield a mean of 155 blocks per specimen, 56 of which contained dye.
The researchers examined 38 breasts, from 35 women. The median age of the women was 49.4 (range, 32 to 87). Thirty-one of the mastectomies were therapeutic23 invasive cancers and 8 ductal carcinomas in situ (DCIS)and 7 were prophylactic (one occult invasive cancer with DCIS), Dr. Khan reported. The mean size of the tumors was 3 cm.
Thirty-four of the breasts (89.5%) produced nipple aspirate fluid, and duct cannulation was successful in 32 (84.2%). The mean number of ductal lavages was 1.4 per mastectomy specimen. Twenty-nine breasts (74.4%) were cytologically evaluable, and 24 breasts (61.5%) were histologically evaluable.
Many False Negatives
When the researchers correlated their cytological findings with the histological findings for each breast, they found significant discordance when the cytological diagnosis was "benign or mild atypia," but excellent correlation when the cytological diagnosis was "marked atypia or malignant."