Survival outcomes of high and intermediate-risk hormone receptor (HR)-positive human epidermal growth receptor-2 (HER2)-negative early breast cancer patients (EBC) who did and did not receive (neo)adjuvant chemotherapy.

Abstract

e12530 Background: Patients with HR-positive HER2-negative EBC have protracted risk of disease relapse despite 5 years of adjuvant endocrine therapy. Combination of endocrine therapy with CDK4/6 inhibitors have shown to improve clinical outcomes in these settings according to MonarchE and NATALEE studies. Prior to the use of adjuvant CDK4/6 inhibitors, (neo)adjuvant chemotherapy in addition to adjuvant endocrine were considered for these patients, and such decision was mainly based on cancer stage. The objective of this study was to determine the survival outcomes of HR-positive HER2-negative EBC cancer patients who did and did not receive (neo)adjuvant chemotherapy. Methods: Patient data from the Hong Kong Breast Cancer Registry was retrieved for this retrospective study. Ethics approval was obtained from regional committee of 11 public and 4 private hospitals/clinics in Hong Kong. Patients who underwent definitive surgery for EBC between January 2006 and December 2011 were categorized into 3 groups: Group 1 consisted of patients who satisfied both MonarchE and NATALEE criteria; Group 2 were those eligible for NATALEE criteria but not MonarchE and Group 3 were remaining patients who mainly had stage 1 cancers. Patients background characteristics were collected. DDFS, iDFS and OS were evaluated using the Kaplan–Meier method. Results: A total of 3078 HR-positive HER2-negative EBC were included: Group 1, n = 912; Group 2, n = 600; Group 3, n = 1566. The number (%) of patients who received (neo)adjuvant chemotherapy were 480 (30.7%) in Group 1, 539 (90.0%) in Group 2 and 856 (94.0%) in Group 3. For patients within Group 2 and Group 3, 10-year iDFS, DDFS and OS were significantly better for those who had received (neo)adjuvant chemotherapy. Specifically, for Group 3, the 10-year iDFS, DDFS and OS among those who did and did not have (neo)adjuvant chemotherapy were 70.5% vs 54.0% (p = 0.028), 75.4% vs 69.5% (p = 0.007) and 80.8% vs 62.5% (p = 0.001). Survival outcomes among Group 1 patients did not differ between those who had or had not received (neo)adjuvant chemotherapy. Conclusions: Our findings confirmed that the role of (neo)adjuvant chemotherapy is significantly associated with improvement in patients’ outcomes in intermediate and high-risk HR-positive HER2-negative EBC patients. High-risk patients who did not receive (neo)adjuvant chemotherapy had dismal outcomes. Acknowledgement: we thank Drs Joanne Chiu and Miranda Chan for their support.