AUTHOR=Wu San-Gang , Zhang Wen-Wen , Wang Jun , Dong Yong , Sun Jia-Yuan , Chen Yong-Xiong , He Zhen-Yu 

TITLE=21-Gene Recurrence Score Assay and Outcomes of Adjuvant Radiotherapy in Elderly Women With Early-Stage Breast Cancer After Breast-Conserving Surgery

JOURNAL=Frontiers in Oncology

VOLUME=9

YEAR=2019

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2019.00001

DOI=10.3389/fonc.2019.00001

ISSN=2234-943X

ABSTRACT=<p><bold>Introduction:</bold> To assess the role of the 21-gene recurrence score (RS) assay on decision-making of postoperative radiotherapy (RT) following breast-conserving surgery (BCS) in elderly women with early-stage breast cancer.</p><p><bold>Methods:</bold> The 21-gene RS for elderly (≥65 years) women with stage T1–2N0M0 estrogen receptor-positive breast cancer who underwent BCS from 2004 to 2015 was obtained from the Surveillance, Epidemiology, and End Results program. We estimated the association of 21-gene RS and adjuvant RT related to breast cancer-specific survival (BCSS) using propensity score matching (PSM).</p><p><bold>Results:</bold> We identified 18,456 patients, of which 15,326 (83.0%) received postoperative RT. Of identified patients, 58.9, 34.0, and 7.1% of patients had a low-, intermediate-, and high-risk RS, respectively. Receipt of postoperative RT was not related to the year of diagnosis according to the 21-gene RS groups. Multivariate analysis suggested that receipt of postoperative RT was an independent predictor of better BCSS before (hazard ratio [HR] 0.587, 95% confidence interval [CI] 0.426–0.809, <italic>P</italic> = 0.001) and after (HR 0.613, 95%CI 0.390–0.963, <italic>P</italic> = 0.034) PSM. However, subgroups analyses indicated that receipt of postoperative RT was related to better BCSS in women with intermediate-risk RS before (HR 0.467, 95%CI 0.283–0.772, <italic>P</italic> = 0.003) and after (HR 0.389, 95%CI 0.179–0.846, <italic>P</italic> = 0.017) PSM, but not in women with low- and high-risk RS groups before and after PSM.</p><p><bold>Conclusions:</bold> Although causation cannot be implied, adjuvant RT in elderly women was associated with a greater effect size in patients with an intermediate-risk RS.</p>