Discordance of intrinsic subtype between primary tumor and lymph node metastasis in breast cancer patients.

). The discordance ratios for intrinsic subtypes between the primary tumor and LN metastasis were analyzed. The discordance ratios for ER, PgR, HER2, and Ki-67 were 0/93 (0%), 7/93 (7.5%), 2/93 (2.2%), and 10/93 (10.8%), respectively. The discordance ratio for the intrinsic subtype was 9/93 (9.7%). Considering the intrinsic subtype of LN metastasis, the effects of additional chemotherapy and anti-HER2 therapy could be expected in 4/93 (4.3%) and 1/93 (1.1%) patients, respectively. The discordance ratio for the intrinsic subtype between the primary breast tumor and LN metastasis was 9.7%. Considering the intrinsic subtype of LN metastasis, additional medical therapy could be expected to be effective in 5/93 (5.4%) breast cancer cases with LN metastasis. Immunohistochemistry of metastatic LNs may be useful for planning adjuvant therapy when the analysis of the primary site is inconclusive.