AUTHOR=Yu Jing , Wu Jiayi , Huang Ou , He Jianrong , Li Zhu , Chen Weiguo , Li Yafen , Chen Xiaosong , Shen Kunwei 

TITLE=Do 21-Gene Recurrence Score Influence Chemotherapy Decisions in T1bN0 Breast Cancer Patients?

JOURNAL=Frontiers in Oncology

VOLUME=10

YEAR=2020

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2020.00708

DOI=10.3389/fonc.2020.00708

ISSN=2234-943X

ABSTRACT=<p><bold>Purpose:</bold> Hormone receptor (HR)-positive breast cancer patients with tumor size ≤1.0 cm and negative node have favorable outcomes. The 21-gene Recurrence Score (RS) could predict response to chemotherapy for HR+ breast cancer, but its role in T1bN0 disease is challenging.</p><p><bold>Methods:</bold> T1bN0 breast cancer patients diagnosed between January 2014 and June 2019 with RS results were included and categorized as Low- (RS &lt; 18), Intermediate- (RS 18–30), or High-risk (RS &gt; 30) groups. Univariate and multivariate analysis were used to assess factors associated with RS distribution and chemotherapy recommendation. Chemotherapy decisions change and patient adherence after 21-gene RS testing were also evaluated.</p><p><bold>Results:</bold> Among 237 patients with T1bN0 tumors, proportions of Low-, Intermediate-, and High-risk RS were 19.8, 63.3, and 16.9%, respectively. Multivariate analysis found that ER expression (<italic>P</italic> = 0.011), PR expression (<italic>P</italic> &lt; 0.001), and Ki-67 index (<italic>P</italic> = 0.001) were independently associated with RS distribution. Adjuvant chemotherapy was recommended for 31.6% of patients, which was more frequently given to patients with higher tumor grade [Odds ratio (OR) = 2.99 for grade II, OR = 59.19 for grade III, <italic>P</italic> = 0.006], lymph vascular invasion (OR = 8.22, <italic>P</italic> = 0.032), Luminal-B subtype (OR = 5.68, <italic>P</italic> &lt; 0.001), and Intermediate-to High-risk RS (OR = 10.01 for Intermediate-risk, OR = 192.42 for High-risk, <italic>P</italic> &lt; 0.001). Chemotherapy decision change was found in 18.6% of patients, mainly in those with Intermediate- to High-risk RS tumor with the majority from no-chemotherapy to chemotherapy. The treatment compliance rate after the 21-gene RS testing with MDT was 95.4%.</p><p><bold>Conclusion:</bold> RS category was related to ER, PR, and Ki-67 expression, which was recognized as an independent factor of chemotherapy recommendation in T1bN0 breast cancer. The 21-gene RS testing would lead to a chemotherapy decision change rate of 18.6% as well as a high treatment adherence, which can be applied in T1bN0 patients.</p>