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Personalised Neoadjuvant Strategy Using 70-Gene Assay in Oestrogen Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer to Increase Breast-Conserving Surgery Rate: A Prospective Cohort Trial Cohort Trial (KBCSG016: PLATO)
Background: We explored the potential of tailored treatments (neoadjuvant chemotherapy [NCT] or endocrine therapy [NET]) guided by a 70-gene assay to improve breast-conserving surgery (BCR) rates in patients with ER-positive/HER2-negative breast cancer.
Patients and Methods: Of the 130 initially screened patients with stage II-IIIA breast cancer deemed unsuitable for BCS enrolled prospectively in four centres in Korea, 92 were finally analysed. Before therapy, surgeons recorded target tumour sizes for BCS based on tumor location and breast size. High-risk patients with 70-gene assay from core needle biopsies received NCT, while low-risk patients received 16–24 weeks of NET with letrozole (±leuprolide for premenopausal women). Post-treatment imaging tumor size was compared to the target size to determine BCS eligibility.\\
Findings: Overall, 68 (73·9%) patients received NCT, while 24 (26·1%) received NET. Clinical T2 tumors were present in 87.0% and T3 in 13.0%. The primary endpoint—achieving the target size for BCS—was reached in 69.6% (95% CI: 59.1-78.7%), significantly surpassing the set goal of 50·8% (p<0·05). The actual overall BCS rate was 59·8% (64·7% for NCT and 45·8% for NET). Pathologic complete response was achieved in 2·2% of the patients, all in the NCT group.
Interpretation: For patients with ER+/HER2– breast cancer who were initially ineligible for BCS, the use of pre-treatment multi-gene assay guided selection for NCT or NET substantially increased BCS rates, avoiding chemotherapy toxicity in low-risk patients.
Keywords: 70-gene assay, breast cancer, breast conserving surgery, neoadjuvant chemotherapy, neoadjuvant endocrine therapy
Han, Wonshik and Kang, Eunhye and Jung, Ji Gwang and Kim, Hong-Kyu and Lee, Han-Byoel and Kim, Jisun and Lee, Saebyeol and Shin, Hee-Chul and Park, Chan Sub and Seong, Min-Ki and Kim, Hyun-Ah and Kim, Eun-Kyu and Son, Byung Ho, Personalised Neoadjuvant Strategy Using 70-Gene Assay in Oestrogen Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer to Increase Breast-Conserving Surgery Rate: A Prospective Cohort Trial Cohort Trial (KBCSG016: PLATO). Available at SSRN: https://ssrn.com/abstract=5095123 or http://dx.doi.org/10.2139/ssrn.5095123
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