Ductal Lavage in Patients Undergoing Mastectomy for Mammary Carcinoma: A Correlative Study

BACKGROUND. Ductal lavage (DL) is a new method for the sampling of breast epithelium. Data regarding its sensitivity in the detection of epithelial abnormalities, including carcinoma in situ (CIS), remains limited. METHODS. DL was performed in the affected breasts of 26 women undergoing mastectomy for mammary carcinoma and in the clinically normal breast of 4 additional women undergoing risk-reducing mastectomy. After surgery, dye was injected through the microcatheter used for DL. Three cytopathologists independently reviewed all DL slides and the data reflect consensus by at least two reviewers. Interobserver agreement was assessed. The findings in DL samples were correlated with the features of CIS in the mastectomy specimens. RESULTS. Four (14%) of 29 DL samples satisfactory for evaluation showed marked atypia, 10 (34%) showed mild atypia, and 15 (52%) were benign. No DL sample was clearly malignant. Interobserver agreement was good (average kappa = 0.52). Of the DL samples satisfactory for evaluation, 27 had been obtained from 24 breasts containing CIS, which included 18 ductal CIS (DCIS), 3 lobular CIS (LCIS), 2 DCIS and LCIS, and 1 solid CIS with mixed ductal and lobular features. Invasive carcinoma was present in 20 samples. Two DL samples from breasts with extensive LCIS showed mild atypia and injected dye was identified in ducts and lobules involved by LCIS. CONCLUSIONS. DL had low sensitivity for CIS in breasts that also contained invasive carcinoma. The use of DL remains investigational, and close follow-up should be continued for all patients undergoing DL, including those with benign diagnosis.