107P - Receptor change on residual disease following neoadjuvant therapies for locally advanced breast cancer fails to impact oncological and survival outcomes

Background

Conventional breast cancer patient management involves prescription of neoadjuvant therapies (NAT). Biomarkers of breast cancer including hormones receptors (ER, PR) and human epidermal growth factors (HER2) can be altered after neoadjuvant chemotherapy. The aim of this study was to evaluate the rate of receptor status change following neoadjuvant therapies and to determine the impact of these changes on oncological and survival outcomes.

Methods

A retrospective cohort study of consecutive female patients undergoing NAT for breast cancer managed in a single institution between 2005-2015 were included. Rates of receptor change were determined using descriptive statistics. The impact of receptor change on locoregional recurrence (LRR), distant disease recurrence (DDR), and overall survival (OS) were determined using Kaplan-Meier (log-rank) analyses.

Results

359 patients were included (mean age: 49.9 years +/- 10.6, range: 23-78) with mean follow up of 100.6 months. Of these, 29.0% achieve a pathological complete response (104/359) and 71.0% had residual disease (RD) following NAC (255/359). Of those with RD, 7.5% had a receptor change (19/255) which failed to impact LRR (P=0.748), DRR (P=0.581) and OS (P=0.325). In total, 3.1% had a change in estrogen receptor status (8/255). which failed to impact LRR (P=0.883) or OS (P=0.483), although trended towards significance with respect to DRR (P=0.096). Similarly, 3.5% had a change in progesterone receptor status (9/255), which failed to impact LRR (P=0.705), DRR (P=0.419) and OS (P=0.114). Additionally, 2.4% experienced a change in human epidermal growth factor receptor-2 (6/255), which failed to impact LRR (P=0.177), DRR (P=0.475) and OS (P=0.223).

Conclusions

Changes to receptor status on RD following NAT fails to impact oncological and survival outcomes for patients being treated for locally advanced breast cancer. However, the frequency of receptor status change supports the need for re-testing. Further immunohistochemistry in residual disease is necessary and further studies are needed to determine influence of receptor status change on treatment algorithms.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

Lambe Institute.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.