Abstract 165P
Background
Residual disease (RD) after neoadjuvant chemotherapy (NAC) correlates highly with triple-negative breast cancer (TNBC) relapse. However, there are event-free, long-survival patients. Combined pathological and immunohistochemical parameters for prognostic stratification can help to select appropriate post-NAC treatment and follow-up.
Methods
We studied RD pathological characteristics of all TNBC patients treated with NAC and surgery from 1994 to 2018 at the Georges-François Leclerc Cancer Centre, France. Expressions of cytokeratin 5/6 (CK5/6), androgen receptor (AR), KI67, human epidermal growth factor receptor 2, p53, forkhead box P3, and CD8 were immunohistochemically assessed on paraffin-embedded surgical sections of post-NAC tumours. Pathologic parameters were analysed retrospectively. Multivariate Cox analyses were used to find variables associated with relapse-free survival (RFS). Cases were stratified into 3 risk groups based on expression status of identified prognostic variables.
Results
Of 111 cases, median age was 50.4 (range 25.6–88.3). NAC was mostly an anthracycline-taxanes sequential regimen (72.1%), and surgical intervention was primarily tumour bed conservatory (51.3%). We found 65.7% with ypT1a and 47.2% with lymph node involvement; 29.4% harboured LVI (lymphovascular invasion). Most residual tumours were positive for CK5/6 (95.5%) and EGFR (87.4%); 50% were positive for AR and 16.4% were negative for p53. After 80 month-median follow-up, 48.6% had relapsed. Median RFS was 62.3 months (95% CI, 37.2 NR). Factors independently associated with poor RFS were ypN+(p<0.001), LVI (p=0.002), and AR negativity (p<0.001). By weighted sum scoring, prognostic variables enabled stratification into 3 subgroups showing significant differences in RFS: HR 2.16, 95% CI [0.91–5.12] for intermediate risk and HR 8.74, 95% CI [3.79–20.16] for high risk reported to low-risk cases (p<0.001).
Conclusions
Post-NAC RD in TNBC showed biomarkers specific to basal-like subtype. We propose a prognostic score of ypN, LVI, and AR as generated subgroups displaying significant different risks of relapse.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
UNICANCER - Georges-Francois Leclerc Cancer Center, Dijon, France.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.