To explore the characteristics of molecular subtyping in elderly breast cancer patients and analyze its relationship with prognosis.

The clinical medical records and follow-up results of 200 elderly (≥65 years) breast cancer patients admitted to the Department of General Surgery, Xuanwu Hospital of Capital Medical University from October 2014 to December 2019 were retrospectively analyzed. The molecular subtypes of all patients were determined according to the immunohistochemical results. They were divided into two subgroups: ≥75 years (77 cases) and <75 years (123 cases). All patients were followed up for 10 to 72 months, median 39 months. χ² test and Kruskal-Wallis H test were used to compare clinicopathological characteristics between two subgroups. The Kaplan-Meier method was used to compare the OS and DFS curves among patients with different molecular subtypes and between two age groups.

Among all cases, there were 51 cases of luminal A subtype, 98 luminal B, 33 triple negative and 18 HER-2 overexpression. During the follow-up, there were eight cases of death, three chest wall recurrence, one axillary lymph node metastasis, one bone metastasis and one lung metastasis. The pathological types, molecular subtypes, surgical methods and clinical stages showed no significant difference between two age groups (≥75 years vs <75 years: χ²=0.546, 5.678, 0.346, Z=-0.684; P=0.460, 0.128, 0.557, 0.494). The molecular subtypes of elderly breast cancer patients were related to clinical stage (F=17.661, P=0.001), but not related to age and axillary lymph node status (F=1.419, 3.558, P=0.238, 0.313). The OS and DFS curves of elderly breast cancer patients showed no significant difference among four molecular subtypes (χ²=3.790, 2.857; P=0.285, 0.414). The patients ≥75 years presented a significantly better OS and DFS compared with patients <75 years (χ²=3.998, 3.919; P=0.046, 0.028).

The patients with a higher age are prone to a poorer prognosis.