Characteristics and prognosis of young breast cancer patients with low expression of estrogen receptor

Abstract

To evaluate the clinical characteristics and prognosis of young breast cancer patients with an ER of 1%–10%. Breast cancer patients aged ≤35 years old were selected and classified into three groups, ER-negative group, ER-low positive group (ER positivity: 1%–10%) and ER-high positive group (ER positivity: ≥10%), to compare their clinicopathological characteristics and prognosis. Of the 1387 patients assessed, 30.4% were ER-negative, 4.3% were ER-low positive, and 65.3% were ER-high positive. There was no difference in age, Tumor Node Metastasis (TNM) stage, histological type, adjuvant chemotherapy and adjuvant radiation therapy among the three groups (p > 0.05). A higher histological grade and greater Human Epidermal Growth Factor Receptor-2 (HER-2) positivity were observed in the ER-low positive group than in the ER-high positive group (p < 0.001). The number of patients with Progesterone Receptor (PR) negative in the ER-low positive group was between the other two groups. The recurrence rate of breast cancer in the ER-low positive group was 27.1%, which was similar to that of the ER-negative group (28%; p > 0.05) but higher than the ER-high positive group (21.4%; p = 0.03). After a median follow-up of 74 months, the ER-high positive group had the longest Disease Free Survival (DFS) compared with the ER-negative group (p < 0.0001) and ER-low positive group (p < 0.05), while there was no significant difference in DFS between the latter two groups (p = 0.73). Similarly, the ER-high positive group had the longest Overall Survival (OS) than the ER-negative group (p < 0.0001) and the ER-low positive group (p < 0.05), while there was no statistical difference in OS between the latter two groups (p = 0.77). After endocrine therapy, no improvement in DFS (p = 0.71) and OS (p = 0.54) was observed in the ER-low positive group. In young breast cancer patients, the clinicopathological characteristics of the ER-low positive group were different from the ER-high positive group but were more similar to the ER-negative group. The DFS and OS were shorter than the ER-high group, and despite receiving endocrine therapy, DFS and OS of the ER-low positive group were not significantly prolonged.