Ki-67 index value and progesterone receptor status can predict prognosis and suitable treatment in node-negative breast cancer patients with estrogen receptor-positive and HER2-negative tumors

Abstract

Gene profiling has identified at least 4 breast cancer subtypes, including Luminal A, Luminal B, HER2-enriched and basal-like, and immunohistochemistry is used as a guide to determine these subtypes. In the present study, patients with ER-positive, HER2-negative and negative nodes were classified into 4 groups according to the PgR and the Ki-67 status and were retrospectively examined. The analysis was based on the clinicopathological findings, and includes the recurrence score (RS) and disease-free survival (DFS) rates. Patients with invasive breast cancer (n=1866) were classified as LA (high PgR/low Ki-67), LB-1 (high PgR/high Ki-67), LB-2 (low PgR/high Ki-67), and LB-3 (low PgR/low Ki-67). In addition, 41 of the cases underwent a 21-gene expression assay. The data revealed that T1 tumors were more prevalent in the LA group and rare in the LB-2 group. Furthermore, nuclear grade 3 and p53 overexpression was revealed to be significantly correlated with LB-2. In terms of prognosis, LA had a significantly more favorable DFS; however, no differences were observed in the LB-3 group. LB-2 had a significantly worse DFS in all cases, and in the cases administered with endocrine therapy alone. Chemotherapy in combination with endocrine therapy was administered to cases with a higher risk of recurrence. In the LB-2 group, there was no difference in the DFS rates between the cases with endocrine therapy and chemo-endocrine therapy. These findings suggest that chemotherapy could improve the DFS in the LB-2 group. In addition, the majority of cases with LA, LB-3 and LB-1 had a RS of ≤25 and the majority of the LB-2 cases had a RS of >25. The patients with LA and LB-3 had a favorable DFS even in the group that received endocrine therapy alone. LB-2 was significantly correlated with a higher degree of malignancy and benefited from chemotherapy. These data suggest that the PgR and the Ki-67 status are effective in predicting prognosis, and for deciding on the most effective treatment strategy in patients with breast cancer.