Heterogeneic expression of estrogen receptor between the primary tumor and the corresponding involved lymph nodes in patients with node-positive breast cancer and its implications in patient outcome.

The estrogen-receptor (ER) status of breast cancers has typically been evaluated in primary tumors (PTs), and the influence of ER expression in the involved lymph nodes (LNs) on prognosis of the patients with node-positive breast cancer remains unclear. The expression of ER was compared between PT and corresponding involved LNs in patients with node-positive breast cancer. Eighty-seven patients with node-positive breast cancer were immunohistochemically assessed to measure the expression of ER in PT and involved LN with anti-ER monoclonal antibody. Thirty-five (40.2%) of PTs and 26 (29.9%) of involved LNs were evaluated as ER(+). The ER expression in PTs was significantly correlated with that in involved LNs (P < 0.0001), and the ER expression was almost the same in both the PT and corresponding involved LN in 66 cases (75.9%): both (+), 20 (23.0%); and both (-), 46 (52.9%). However, ER expression differed in 21 cases (24.1%) between involved LN and the corresponding PT: PT-ER(+)/LN-ER(-), 15 (17.2%); and PT-ER(-)/LN-ER(+), 6 (6.9%). The survival of patients with ER(+)-PT was significantly better than that of ER(-)-PT patients (P = 0.0086), but ER expression in involved LN did not have any significant effect on patient survival. Furthermore, when survival periods were grouped by coexpression of ER in the PT and involved LN, the best survival was seen in the PT-ER(+)/LN-ER(-) group (P < 0.001 vs. others). In the patients, who received adjuvant endocrine therapy, the survival of the PT-ER(+) group was significantly better than that of PT-ER(-) group (P = 0.0145), but LN-ER expression did not show any significant influence on the survival rate. Multivariate analysis demonstrated that clinical stage and ER-expression in the PT were significant variables, but ER expression in the involved LN was not. The ER expression was discordant between PT and involved LN in about 24% of the breast cancers evaluated, and ER expression in involved LNs had less influence on patient prognosis than ER expression in the corresponding PT.