Miller–Payne Grading and 70-Gene Signature Are Associated With Prognosis of Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Early-Stage Breast Cancer After Neoadjuvant Chemotherapy

INTRODUCTION: HR+/HER2− breast cancer (BC) has a much lower pathological complete response (pCR) rate to neoadjuvant chemotherapy (NAC). Therefore, to better stratify the relapse risk for HR+/HER2− non-pCR populations, it is essential to accurate identification new prognostic markers. MATERIALS AND METHODS: The study retrospectively analyzed 105 stage II–III patients who were diagnosed with HR+/HER2− BC and received NAC followed by breast and axilla surgery between 2013 and 2019 in Sun Yat-Sen University Cancer Center. The Miller–Payne (MP) grading system was used to evaluate pathological responses to NAC. The 70-gene signature was used to classify the prognosis signatures. RESULTS: Among the 105 patients, the study demonstrated that larger tumor size and lower progesterone receptor level at baseline and larger tumor size postoperative were statistically significantly associated with worse disease-free survival (DFS) (p = 0.004, p = 0.021, and p = 0.001, respectively). Among 54 patients who underwent the 70-gene assays, 26 (48.1%) had a low-risk signature; 28 (51.9%) patients had a high-risk signature. Patients with poor response (MP grades 1–2) were more likely to with a high-risk 70-gene signature than those with good response (MP grades 4–5). The final analysis showed that DFS was longer in the low-risk group than in the high-risk group [52.4 vs. 36.1 months of the median DFS, hazard ratio (HR) for recurrence, 0.29; 95% confidence interval (CI), 0.10–0.80; p = 0.018]. DFS was longer in the good response (MP grades 3–4) group than in the poor response (MP grades 1–2) group (94.7% vs. 60% of the patients free from recurrence; HR, 0.16; 95% CI, 0.05–0.47; p = 0.037). When stratified by MP grades combined with the 70-gene signature, subgroup analyses showed the good-response low-risk group with the best DFS, whereas the poor-response high-risk group showed the worst DFS (p = 0.048). Due to the short median follow-up time of 34.5 months (5.9–75.1 months), MP grades and the 70-gene signature did not show significant prognostic value for overall survival. CONCLUSION: The study showed that analysis of MP grades combined with the 70-gene signature with residual NAC-resistant breast samples has a significant correlation with DFS.