514 Background: The 21- gene Breast Recurrence Score predicts benefit from adjuvant chemotherapy in estrogen receptor positive (ER+), HER-2 negative (-) breast cancer (BC). We aimed to examine whether the 21-gene assay predicts response to neoadjuvant chemotherapy (NAC). Methods: We identified patients with stage I-III ER+/HER2− BC treated with NAC from the Young Women's Breast Cancer Study, a prospective cohort of women diagnosed with BC at age ≤ 40 years. The 21-gene assay was performed on tumor specimens removed prior to NAC either as part of clinical care or retrospectively for research. Pathologic complete response (pCR) was defined as no residual invasive tumor (ypT0/is ypN0). The relationship between Recurrence Score result (RS) and pCR was evaluated using logistic regression modeling. Results: 76 women in the cohort had undergone NAC for ER+, HER2- BC and were eligible for this analysis: 5 had undergone clinical 21-gene assay testing, 71 had banked specimens retrospectively tested. Median age at diagnosis was 36.7 (24.3-40). Most tumors were of ductal histology (78%), high grade (51%), progesterone receptor (PgR) positive (86%), ≥T2 (88%), clinically node positive (74%), and anthracycline and taxane containing protocols were administered in 86% of cases. RS ranged between 5-75 with 50% > 25 and only 4 < 11. Mean RS was significantly higher among tumors achieving pCR vs. non-pCR response (51.9 vs. 26.6, pwilcoxon= 0.0005). pCR rate in patients with RS > 25 was 21% (8/38) vs. 5% in patients with RS < 25 (2/38), with both pCRs in the <25 group in patients with RS 21-25. In univariable analysis, PgR negativity (odds ratio (OR) 5.62, 95% confidence interval (CI) 1.27-24.89, p = 0.02), high grade (OR 9.03, 95%CI 1.07-76.32, p = 0.04) and higher RS as a continuous variable (OR 1.08, 95%CI 1.04-1.13, p = 0.0003) were associated with a greater likelihood of pCR. In multivariable analysis only RS remained significantly associated with pCR (OR: 1.07, 95%CI 1.01-1.12, p = 0.01): a 7% increase in the odds of pCR for every 1-point increase in RS. Conclusions: In young women with ER+, HER2- BC who received NAC, higher pretreatment RS was associated with an increased likelihood of pCR. Genomic expression profiling assays may have a role in decision-making in young women in need of neoadjuvant therapy. For women with low likelihood of benefiting from NAC, alternative approaches are clearly warranted. Given the demonstrated efficacy of neoadjuvant endocrine therapy in post-menopausal women, further evaluation in young women should be pursued.
Neoadjuvant Hormonal Therapy is Associated with Comparable Outcomes to Neoadjuvant Chemotherapy in Post-Menopausal Women with Estrogen Receptor-Positive Breast Cancer
