Treatment patterns and outcomes according to age among older patients with early breast cancer: a retrospective study

Background: Breast cancer is increasingly diagnosed in older adults because of population aging; however, evidence supporting perioperative chemotherapy in patients aged ≥ 75 years remains limited. Real-world treatment patterns and their association with clinical outcomes in this population have not been well characterized. This study aimed to evaluate age-related differences in perioperative treatment patterns and clinical outcomes among older patients with early breast cancer in routine clinical practice. Methods: We retrospectively reviewed 171 patients aged ≥ 65 years with stage I–III breast cancer who underwent surgery in 2007–2016 and met institutional indications for perioperative chemotherapy. Patients were grouped as 65–74 years or ≥ 75 years. Clinicopathological characteristics, treatment patterns, disease-free survival (DFS), overall survival (OS), breast cancer-specific survival (BCSS), and prognostic factors were analyzed. Results Compared with patients aged 65–74 years, those aged ≥ 75 years were less likely to receive chemotherapy (4.3% vs. 56.4%; P < 0.001), anti-HER2 therapy, or radiotherapy, whereas use of hormone therapy was similar. Tumor stage and receptor subtype distributions did not differ between groups. Five-year DFS (P = 0.3311) and BCSS (P = 0.175) were comparable, although OS (P = 0.0466) was lower in patients aged ≥ 75 years. Multivariable analysis identified age ≥ 75 years, stage III disease and high nuclear grade and/or Ki-67 as independent prognostic factors for OS. Conclusions Despite substantially lower use of perioperative chemotherapy in patients aged ≥ 75 years, disease-free and breast cancer-specific survival were comparable between the age groups. Since only three patients aged ≥ 75 years received chemotherapy, these findings should not be interpreted as evidence regarding chemotherapy efficacy. Rather, they describe real-world treatment patterns in older Japanese patients with early breast cancer and support an individualized approach to treatment consistent with current guideline recommendations.