Incidence and Clinical Significance of Lymph Node Metastasis Detected by Cytokeratin Immunohistochemical Staining in Ductal Carcinoma In Situ

Background This study explored the long-term prognosis of patients with ductal carcinoma-in-situ (DCIS) and lymph node metastasis detected by cytokeratin immunohistochemical stains (CK-IHC).Methods Using the Columbia University breast cancer database, we identified all DCIS patients who had eight or more axillary nodes dissected and free of metastasis. Five-micrometer sections from all paraffin blocks containing lymph node tissue were stained with an anticytokeratin antibody cocktail (AE1/AE3 and KL1). The results of the CK-IHC and updated database were anonymized and merged. Survival of CK-IHC–positive and –negative patients was compared by using Kaplan-Meier curves and log-rank tests.Results CK-IHC was performed on 301 DCIS patients, who had an average of 16.7 axillary nodes dissected. Eighteen (6%) of 301 patients tested positive by CK-IHC. Seventy patients with bilateral breast cancer and 2 patients without any follow-up data were excluded, for a final study population of 229 patients. Among the 216 patients with negative CK-IHC, 18 patients died, compared with 1 of 13 patients with positive CK-IHC. The median follow-up for the study group was 127 months. Kaplan-Meier overall and breast cancer–specific survival estimates were similar for CK-IHC–positive and –negative patients (P = .81 and P = .73, respectively).Conclusions CK-IHC increases the incidence of positive nodes by 6% in DCIS patients. A positive node by CK-IHC does not seem to affect survival in these patients. These results raise concerns regarding the clinical significance of positive nodes by CK-IHC in DCIS patients.