Effect of neoadjuvant chemotherapy on histologic grade and expression of biological markers in breast cancer

Abstract

The aim of this study is to investigate the changes of expression of estrogen receptors (ER), progesterone receptors (PR), Her-2, Ki-67 and histological grade after neoadjuvant chemotherapy in breast cancer. Sixty-seven patients with histopathalogically confirmed breast cancer by core needle biopsy received neoadjuvant chemotherapy. The effect of neoadjuvant chemotherapy was assessed according to the criteria of the Japanese Breast Cancer Society: non-effective (G1), mildly effective (G2), moderately effective (G3), markedly effective (G4) and completely effective (G5). All pathological slides were retrospectively reviewed. Immunohistochemical staining (EnVision method) was used to detect the expression of ER and PR, Her-2 and Ki-67. The pre- and post-neoadjuvant chemotherapy status of tumor histological grade, ER and PR, Her-2 and Ki-67 expression in the 49 cases were compared. The effect of neoadjuvant chemotherapy was assessed in 67 patients. There were 5 cases (7.5%) in G1, 19 in G2 (28.4%), 20 in G3 (29.9%), 17 in G4 (25.4%) and 6 in G5 (9.0%), respectively. PR positive rate was 71.4% after chemotherapy versus 91.8% before chemotherapy, with a statistically significant reduction (P = 0.021). However, the ER and Her-2 expression before and after neoadjuvant chemotherapy was stable. Of the patients with invasive ductal carcinoma, 28.6% had histological grade change after neoadjuvant chemotherapy, and 85.7% of patients decreased one grade. The proportion of histological grade change in the G1, G2, G3, G4 were 0, 5.9%, 41.2% and 54.5%, respectively (P = 0.013). The average rate of Ki-67 expression decreased from 28.3% pre-chemotherapy to 11.0% post-chemotherapy (P = 0.011). After the neoadjuvant chemotherapy, the Ki-67 expression rate decreased by > 10%, > 20%, > 30%, > 40% and > 50% in 3 groups (G1 and G2, group G3, group G4 and G5) showed a tendency to be increased, with a significant difference (P < 0.05). PR expression in breast cancer decreases after neoadjuvant chemotherapy, while ER and Her-2 expressions remain stable. After neoadjuvant chemotherapy, the histological grade and proliferation index are decreased and correlated with the response to chemotherapy. Therefore, histological grade and proliferation index may be effective complementary factors in assessment of the effectiveness of neoadjuvant chemotherapy.