Abstract 140P
Background
Young age is a poor prognosis factor in early-stage breast cancer (BC), regardless of molecular subtype or stage at diagnosis. Yet, evidence to support adjuvant chemotherapy in luminal A-like patients aged 40 years or younger is limited. The primary objective of this study was to examine the impact of adjuvant chemotherapy (aCT) on outcomes in this population.
Methods
Patients ≤40 years of age were retrospectively identified from a large cohort of 23,134 early BC patients who underwent primary surgery at 15 academic cancer centers between 1990 and 2014. Luminal A-like tumors were defined on the basis of low SBR tumor grade (1 or 2), endocrine receptors positivity, and HER2 negativity. Patients who received neoadjuvant chemotherapy were excluded. Endpoints were disease-free survival (DFS) and overall survival (OS). A multivariate Cox model including aCT, endocrine therapy (ET), radiation therapy (RT), tumor size, grade, and nodal status was built.
Results
Of a total of 464 patients under 40 years old with luminal A-like tumors, 169 received aCT. Median age at diagnosis was 37.87 years. Patients who received aCT had more unfavorable prognostic features, such as age ≤35 years, large tumor size, high grade, lymphovascular invasion, and macroscopic lymph-node involvement. Factors independently associated with aCT prescription were treatment period, grade, ET prescription, and tumor size. In multivariate Cox analysis, we observed a statistical significant benefits of aCT on OS (HR=0.21, 95% CI [0.05-0.84]; p=0.028), but not on DFS (0.57, 95% CI [0.27-1.22]; p=0.147). Other variables independently associated with OS were tumor size, macroscopic lymph-node involvement and RT use. Only tumor size was independently associated with DFS in this cohort.
Conclusions
Luminal A-like patients aged 40 years or younger derive significant OS benefits from aCT. The trend favoring aCT use observed for DFS did not reach statistical significance. Further analysis/meta-analysis would be warranted given the incidence of this type of cancer, and the need to identify subgroups that would benefit most from systemic treatments.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Institute Paoli-Calmettes.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.