Radiotherapy in Elderly Breast Cancer Patients

The treatment of elderly patients with breast cancer often differs from the interdisciplinary therapy recommendations in real world clinical practice. Therapy decisions are not only influenced by tumor-specific characteristics, but also by other factors such as co-morbidities, expected side effects and patient preference. The aim of the present study was to evaluate the oncological outcome of radiotherapy (RT) in older patients (> 65 years) treated in a modern clinical setting outside of clinical studies. We investigated all patients diagnosed with breast cancer, age> 65 years at two large breast centers, with a subgroup analysis of low-risk patients (breast-conserving surgery (BCS), pT1pN0, pT2pN0, R0, hormone receptor positive, Her2neu negative). Local recurrence-free (LRFS), lymph node recurrence-free (LNRFS), distant metastasis-free survival (DMRFS) and overall survival (OS) was determined using the Kaplan-Meier method. Prognostic factors were identified using multivariate Cox regression analysis. 4,469 women with a median follow-up of 90.8 months were included. 1170/4469 received a mastectomy (ME) and 3171/4469 BCS, while 128/4469 had no surgery. Adjuvant RT was performed in 396/1170 of ME, 2599/3171 of BCS and in 17/128 for non-operated patients. RT patients in both groups received more additional chemotherapy (p <0.001) and endocrine therapy (p = 0.014). Adjuvant RT improved locoregional tumor control after BCS (10-year risk for local recurrence: 93.4% BEO + RT vs. 77.6% BCS alone, p <0.001, 10-year risk for lymph node recurrence: 98.2% BCS + RT vs 94.3%, p <0.001), while this was not significant in the ME group. In the multivariate analysis, a HR of 3.121 (95% CI: 2.239-4.352, p <0.001) showed an advantage for local tumor control for postoperative RT. The 10-year risk of distant metastases was also reduced by RT after BCS (HR 1.667; 95% CI: 1.320-2.106, p <0.001) with improved overall survival (p <0.001). In the subgroup of low-risk patients (n = 1132), 91.3% (1034/1132) received adjuvant RT after BCS with an improvement in locoregional tumor control (10-year local recurrence-free survival (LRFS) 96.5% with RT vs. 65.5% without RT, p <0.001). Patients who received endocrine therapy (631/1132) also benefited from RT (10-year LRFS 97.9% with RT vs. 64.1% without RT, p <0.001). RT also resulted in a reduction of locoregional lymph node recurrence (p = 0.004), while endocrine therapy could not affect this (p = 0.873). RT did not lead to an improvement in DMRFS (p = 0.774). Our results confirms the effectiveness of postoperative RT for breast cancer in older patients (> 65 years). RT influences local and distant control, even in low-risk patients who receive endocrine therapy.