Lumpectomy plus Endocrine Therapy or Irradiation in Women Age 70 Years or Older with Hormone Receptor-Positive Early Breast Cancer: An Analysis of the National Cancer Database

Abstract

Interest exists for de-intensification of adjuvant therapy in the treatment of early stage, biologically favorable breast cancer in elderly women. CALGB C9343 examined women ≥70 years (ER+, stage I) treated by lumpectomy followed by either adjuvant endocrine therapy (ET) + radiation therapy (RT), or ET alone with a median follow up of 12.6 years. They found no difference in survival (OS) between the groups. PRIME II evaluated women ≥65 years (ER/PR+, T1-2N0) treated with lumpectomy followed by either adjuvant ET or ET+RT with a median follow up of 5 years. They found no differences in overall survival outcomes. Both studies concluded that consideration could be given for omission of RT in this setting. However, toxicity from ET is not trivial and adherence rates range from 40-90%. We hypothesize that de-escalation with use of RT and omission of ET would have comparable survival outcomes in healthy elderly women with early stage breast cancer. Patients ≥70 years of age with a Charlson/Deyo (CD) score 0-1 in the National Cancer Database (2010-2014), with T1N0 hormone receptor positive, HER-2 negative breast cancer, who were treated with lumpectomy and either adjuvant ET alone or adjuvant RT alone, were identified. To reduce the impact of treatment selection bias, propensity scores were used to match patients based on age, CD score, education, income, and geographical location. OS was measured from the time of diagnosis to the time of death and was estimated using the Kaplan-Meier method and compared using stratified log-rank test. A total of 2,995 patients, with a median age of 78 years (range 70-90), met inclusion criteria. The majority of patients had CD score 0 (81%), white ethnicity (91%), clinical stage IA disease (77%), and were ER/PR+ (100%/91%). Of these, 65% (n=1,957) were treated with adjuvant ET alone and 35% (n=1,038) were treated with adjuvant RT alone, following lumpectomy. On multivariate analysis of the matched cohort, older age (HR 1.10, p<0.001) and a CD score of 1 (HR 1.92, p=0.0002) predicted for worse survival; living in an Urban area compared to a metropolitan area portended for improved survival (HR 0.32, p=0.004). Income level and education level did not predict for survival. The median follow up time for all patients was 45 months and the 5-year OS rate in the matched cohort was 85% in both groups. There was no difference in OS between patients treated with adjuvant ET or RT (p=0.41). Healthy (CD 0-1) older patients with hormone receptor positive, HER-2 negative breast cancer treated with lumpectomy followed by either adjuvant RT or ET have equivalent 5 year survival outcomes. Given the relatively high rates of non-compliance with adjuvant ET, a randomized controlled trial to confirm the favorable outcomes we report with either adjuvant RT or adjuvant ET is warranted.