A comparative study of the clinical characteristics and outcomes of HR-positive HER2-negative breast cancer patients over and under 65 years old.

Purpose: The purpose of this study was to compare the clinical characteristics and outcomes of hormone receptor-positive (HR+) human epidermal growth factor 2-negative (HER2-) breast cancer among elderly patients (over 65 years old) and younger patients. Methods: This was a retrospective cohort study of 328 patients who were treated for breast cancer at Pusan National University Yangsan Hospital between January 2009 and December 2014. Tumor characteristics, surgical methods, and survival outcomes were compared between the two age groups (<65 and ≥65 years old). Kaplan-Meier curves for disease-free survival (DFS) and overall survival (OS) were also constructed according to the age groups. Results: Among the 328 patients with HR+ HER2- breast cancer, 184 (56.1%) were <65 years old and 144 (43.9%) were ≥65 years old. Breast cancer stages were similar between the two age groups, but the older patients were treated less often with chemotherapy (81% vs. 66%, P=0.002). During the follow-up period, 17 deaths and 36 cases of recurrence or metastasis were reported. There was no difference in DFS between the two groups (P=0.840); however, the OS of the older age group was significantly lower than that of the younger age group (P=0.015). Conclusion: This study suggested that HR+ HER2- breast cancer patients belonging to the two age groups had no significant difference in DFS. However, older age is an independent factor affecting OS rate. Therefore, even if patients are old, but their physical condition is satisfactory, standard and active treatment may be necessary, similar to that given to younger patients.