Omission of Adjuvant Radiotherapy in the Elderly Breast Cancer Patient: Missed Opportunity?

PURPOSE: We used the National Cancer Data Base to analyze practice patterns of adjuvant breast radiotherapy (RT) in elderly patients to see if a difference in overall survival (OS) could be detected. Additionally, we investigated factors that affected OS in these patients. PATIENTS AND METHODS: Women aged ≥ 65 years with hormone receptor-positive and human epidermal growth factor receptor 2 (HER2)-negative pathologic T1-T2N0M0 invasive breast cancer measuring up to 3 cm who were treated with breast conservation and adjuvant endocrine therapy without adjuvant chemotherapy were identified and stratified by use of adjuvant RT. Multivariable Cox proportional hazards modeling was used to examine the association of treatment and mortality adjusting for demographic, socioeconomic, and clinicopathologic factors. Kaplan-Meier analysis was used to estimate overall 5-year survival in patients who did or did not receive adjuvant RT, and to compare those groups.
RESULTS: A total of 61,395 patients with a median follow-up of 48.7 months (range, 0-107 months) were identified. On Cox regression analysis, improved OS was associated with treatment at an academic facility, younger age, higher income level, lower Charlson-Deyo comorbidity index, and receipt of adjuvant RT (all P < .05). The overall 5-year survival rate was 93.0% (95% confidence interval 92.7-93.3) in the adjuvant RT group and 83.6% (95% confidence interval 82.5-84.7) in the nonadjuvant RT group (P < .0001).
CONCLUSION: Improved survival is associated with the receipt of adjuvant RT for older women with early-stage hormone receptor-positive HER2-negative breast cancer who received adjuvant endocrine therapy. However, there are many limitations inherent to a retrospective database study such as ours, so the findings should be taken with caution.