Endocrine therapy (ET) has established itself as an efficacious treatment for estrogen receptor-positive (ER+) breast cancers, with a reduction in recurrence rates and increased survival rates. The pre-surgical approach with chemotherapy (NCT) has become a common form of management for large, locally advanced, or high-risk tumors. However, a good response to NCT is not usually expected in ER+ tumors. Good results with primary ET, mainly in elderly women, have encouraged studies in other stages of life, and nowadays neoadjuvant endocrine treatment (NET) has become a useful approach to many ER+ breast cancers. The aim of this review is to provide an update on the current state of art regarding the present and the future role of NET.

Neoadjuvant endocrine therapy for luminal breast cancer treatment: a first-choice alternative in times of crisis such as the COVID-19 pandemic Cova

Purpose: The aim of this study is to describe our initial experience using magnetic seeds (Magseed^®) to guide breast-conserving surgery in non-palpable breast lesions and compare the use of magnetic seed with wires to guide breast-conserving surgery in terms of clinical and pathological characteristics. Methods: We performed a retrospective study including all breast-conserving surgeries for non-palpable breast lesions under 16 mm from June 2018 to May 2021. We compared breast-conserving surgeries guided with magnetic seeds (Magseed^®) to those guided with wires, analyzing tumor and patient characteristics, surgical time, and pathological results of the surgical specimens. Results: Data from 225 cases were collected, including 149 cases guided by magnetic seeds and 76 cases guided by wires. The breast lesion was localized in every case. Both cohorts were similar regarding clinical and pathological characteristics. We found significant statistical differences (p < 0.02) in terms of the median volume (cm³) of the excised specimen, which was lower (29.3%) in the magnetic seed group compared with the wire group (32.5 [20.5–60.0]/46.0 [20.3–118.7]). We did not find significant differences regarding surgical time (min) or the affected or close margins. Conclusion: In our experience, the use of magnetic seed (Magseed^®) is a feasible option to guide breast-conserving surgery of non-palpable lesions and enabled us to resect less breast tissue.

Purpose: Neoadjuvant endocrine treatment (NET) has become a useful tool for the downstaging of luminal-like breast cancers in postmenopausal patients. It enables us to increase breast conserving surgery (BCS) rates, and provides an opportunity for assessing in vivo NET effectiveness and studying any biological changes that may act as valid biomarkers. The purpose of this study was to evaluate the safety and effectiveness of NET, and to assess the role of Ki67 proliferation rate changes as an indicator of endocrine responsiveness.Methods: From 2016 to 2020, a single-institution cohort of patients treated with NET and further surgery was evaluated. In patients with Ki67≥10%, a second core biopsy was performed after four weeks. Information regarding histopathological and clinical changes was gathered.Results: A total of 115 estrogen receptor positive (ER+)/HER2 negative patients were included. The median treatment duration was 5.0 months (IQR: 2.0-6.0). Median maximum size in the surgical sample was 40% smaller than pretreatment size measured by ultrasound (p<.0001). Median pretreatment Ki67 expression was 20.0% (IQR: 12.0-30.0), and was reduced to 5.0% (IQR: 1.8-10.0) after four weeks, and to 2.0% (IQR: 1.0-8.0) in the surgical sample (p<.0001). BCS was performed on 98 patients (85.2%). No pathological complete responses were recorded. A larger Ki67 fold-change after four weeks was significantly related to a PEPI score of 0 (p<.002). No differences were observed between luminal A- and B-like tumors with regard to fold-change and PEPI score.Conclusions: In our cohort, NET has proven effective for tumor size and Ki67 downstaging. This results in a higher rate of conservative surgery, aids in therapeutic decision-making, provides prognostic information, and constitutes a safe and well-tolerated approach