Current Status of Neoadjuvant Endocrine Therapy in Early Stage Breast Cancer

Neoadjuvant therapy in hormone Receptor-Positive/HER2-Negative breast cancer

Neoadjuvant therapy is commonly used in patients with locally advanced or inoperable breast cancer (BC). Neoadjuvant chemotherapy (NACT) represents an established treatment modality able to downstage tumours, facilitate breast-conserving surgery, yet also achieve considerable pathologic complete response (pCR) rates in HER2-positive and triple-negative BC. For patients with HR+/HER2- BC, the choice between NACT and neoadjuvant endocrine therapy (NET) is still based on clinical and pathological features and not guided by biomarkers of defined clinical utility, differently from the adjuvant setting where gene-expression signatures have been widely adopted to drive decision-making. In this review, we summarize the evidence supporting the choice of NACT vs NET in HR+/HER2- BC, discussing the issues surrounding clinical trial design and proper selection of patients for every treatment. It is time to question the binary paradigm of responder vs non-responders as well as the "one size fits all" approach in luminal BC, supporting the utilization of continuous endpoints and the adoption of tissue and plasma-based biomarkers at multiple timepoints. This will eventually unleash the full potential of neoadjuvant therapy which is to modulate patient treatment based on treatment sensitivity and surgical outcomes. We also reviewed the current landscape of neoadjuvant studies for HR+/HER2- BC, focusing on antibody-drug conjugates (ADCs) and immunotherapy combinations. Finally, we proposed a roadmap for future neoadjuvant approaches in HR+/HER2- BC, which should be based on a staggered biomarker-driven treatment selection aiming at impacting long-term relevant endpoints.

Changing the Surgical Approach to Breast Diseases During the COVID-19 Pandemic Period

Background Postponing elective surgeries during the COVID-19 pandemic has also affected the approach to both malignant and benign breast diseases. This paper aims to share how the COVID-19 pandemic affects our approach to breast cancer, benign breast cases, and the procedures' results. Methodology A cross-sectional study was conducted in a tertiary-level public hospital in Istanbul, Turkey. We retrospectively analyzed our treatment options for patients diagnosed with breast cancer and benign breast disease in the general surgery clinic of a tertiary hospital that declared a pandemic status between March 11, 2020, and June 1, 2020. Results The number of patients who visited the breast outpatient clinic and received a diagnosis of breast cancer was 23. Among the benign diseases, no intervention was made except for abscess (eight patients, 40%) and mastitis (12 patients, 60%). Conclusions Patients with acute abscesses and mastitis were treated for both diagnostic and therapeutic purposes. Chemotherapy and hormone therapy were chosen for those diagnosed with cancer. Priority was given to oncology protocols rather than surgical approaches during the pandemic. We think that different approaches will be defined as the pandemic continues.

Toward a Value-Based Therapy Recommendation Model

Patient value is an important factor in clinical decision making, but conventionally, it is not incorporated in the decision processes. Clinical decision making has some clinical guidelines as a reference. There are very few value-based clinical guidelines, but knowledge about how values affect decision making is mentioned in some scattered studies in the literature. We use a literature review method to extract evidence and integrate it as part of the decision-making model. In this paper, a value-based therapy recommendation comprehensive model is proposed. A literature analysis is conducted to collect value-based evidence. The patients' values are defined and classified with fine granularity. Categorized values and candidate therapies are used in combination as filtering keywords to build this literature database. The literature analysis method generates a literature database used as a source of arguments for influencing decision making based on values. Then, a formalism model is put forward to integrate the value-based evidence with clinical evidence, and the literature databases and clinical guidelines are collected and analyzed to populate the evidence repository. During the decision-making processes, the evidence repository is utilized to match patients' clinical information and values. Decision-makers can dynamically adjust the relative importance of the two pieces of evidence to obtain a treatment plan that is more suitable for the patient. A prototype system was implemented using a case study for breast cancer and validated for feasibility and effectiveness through controlled experiments.

Prediction of Ki-67 of Invasive Ductal Breast Cancer Based on Ultrasound Radiomics Nomogram

PURPOSE

The objective of this research was to develop and validate an ultrasound-based radiomics nomogram for the pre-operative assessment of Ki-67 in breast cancer (BC).

MATERIALS AND METHODS

From December 2016 to December 2018, 515 patients with invasive ductal breast cancer who received two-dimensional (2D) ultrasound and Ki-67 examination were studied and analyzed retrospectively. The dataset was distributed at random into a training cohort (n = 360) and a test cohort (n = 155) in the ratio of 7:3. Each tumor region of interest was defined based on 2D ultrasound images and radiomics features were extracted. ANOVA, maximum correlation minimum redundancy (mRMR) algorithm, and minimum absolute shrinkage and selection operator (LASSO) were performed to pick features, and independent clinical predictors were integrated with radscore to construct the nomogram for predicting Ki-67 index by univariate and multivariate logistic regression analysis. The performance and utility of the models were evaluated by plotting receiver operating characteristic (ROC) curves, decision curve analysis (DCA), and calibration curves.

RESULTS

In the testing cohort, the area under the receiver characteristic curve (AUC) of the nomogram was 0.770 (95% confidence interval, 0.690-0.860). In both cohorts, the nomogram outperformed both the clinical model and the radiomics model (P < .05 according to the DeLong test). The analysis of DCA proved that the model has clinical utility.

CONCLUSIONS

The nomogram based on 2D ultrasound images offered an approach for predicting Ki-67 in BC.

Clinical implication of low estrogen receptor (ER-low) expression in breast cancer

Breast cancer is a heterogeneous disease, and the estrogen receptor (ER) remains the most important biomarker in breast oncology. Most guidelines set a positive expression threshold of 1% staining in immunohistochemistry (IHC) to define ER positivity. However, different expression levels may be associated with diverse degrees of sensitivity to endocrine therapy as ER expression may impact breast cancer molecular biology as a continuous variable. ER-lo tumors, defined as those with 1-10% ER expression, represent a relatively small subgroup of breast cancer patients, with an estimated prevalence of 2-7%. These tumors are similar to ERneg disease in their molecular landscape, clinicopathological characteristics, prognosis, and response to therapy. Nevertheless, a proportion may retain some degree of ER signaling dependency, and the possibility of responding to some degree to endocrine therapy cannot be completely ruled out. This review article discusses the most important considerations regarding the definition of ER positivity, pathology assessment, prognosis, and therapeutic implication of ERlo breast cancer from the medical oncology perspective.

Effectiveness and safety of pegylated liposomal doxorubicin versus epirubicin as neoadjuvant or adjuvant chemotherapy for breast cancer: a real-world study

BACKGROUND

Pegylated liposomal doxorubicin (PLD) is an improved formulation of doxorubicin with comparable effectiveness but significantly lower cardiotoxicity than conventional anthracycline. This study aimed to evaluate the real-world effectiveness and safety of PLD versus epirubicin as neoadjuvant or adjuvant treatment for breast cancer.

METHODS

Clinical data of invasive breast cancer patients who received neoadjuvant or adjuvant chemotherapy with PLD or epirubicin were retrospectively collected. Propensity score matching (PSM) was performed to reduce the risk of selection bias. The molecular typing of these patients included Luminal A, Luminal B, HER2-positive, and basal-like/triple-negative. The primary outcome was pathological complete response (pCR) rate for neoadjuvant chemotherapy and 3-year disease-free survival (DFS) rate for adjuvant chemotherapy. Noninferiority was suggested if the lower limit of the 95% CI for the 3-year DFS rate difference was greater than - 10%. The secondary outcome was adverse reactions.

RESULTS

A total of 1213 patients were included (neoadjuvant, n = 274; adjuvant, n = 939). pCR (ypT0/Tis ypN0) rates of patients who received neoadjuvant chemotherapy were 11.6% for the PLD group and 7.0% for the epirubicin group, but the difference was not statistically significant (P = 0.4578). The 3-year DFS rate of patients who received adjuvant chemotherapy was 94.9% [95%CI, 91.1-98.6%] for the PLD group and 95.4% [95%CI, 93.0-97.9%] for the epirubicin group (P = 0.5684). Rate difference between the two groups and its 95% CI was - 0.55 [- 5.02, 3.92]. The lower limit of the 95% CI was - 5.0% > - 10.0%, suggesting that PLD is not be inferior to epirubicin in adjuvant chemotherapy for breast cancer. The incidences of myelosuppression, decreased appetite, alopecia, gastrointestinal reactions, and cardiotoxicity were lower in the PLD group than in the epirubicin group, while the incidence of nausea was higher in the PLD group.

CONCLUSIONS

In the neoadjuvant and adjuvant treatment of breast cancer, effectiveness is similar but toxicities are different between the PLD-containing regimen and epirubicin-containing regimen. Therefore, further study is warranted to explore PLD-based neoadjuvant and adjuvant chemotherapy for breast cancer.

Neoadjuvant Endocrine Therapy in Clinical Practice: A Review

Importance

In clinical practice, neoadjuvant endocrine therapy (NET) is rarely used despite being an effective treatment modality able to downstage tumors and facilitate breast-conserving surgery.

Observations

Using data from studies conducted since 2000, we provide readers with a critical in-depth review on clinical aspects related to the application of NET in the treatment of hormone receptor (HR)-positive/ERBB2 (formerly HER2)-negative breast cancer. This includes an overview of patient-selection criteria, regimen choice, treatment duration, evaluation of response by imaging, interpretation of pathology after treatment, and surgical considerations. Areas of controversy include the use of gene-expression tests for patient selection, treatment of premenopausal women, surgical management of the axilla after NET, and adjuvant systemic therapy decision-making, including the use of chemotherapy.

Conclusions and Relevance

NET is an optimal treatment modality for a considerable proportion of postmenopausal women diagnosed with HR-positive tumors. The treatment landscape for HR-positive breast cancer is evolving, with novel agents and the growing use of gene expression profiling to define treatment selection. As such, it is likely that NET use will increase and the practical considerations outlined here will become more important.

Surgical Management of Axilla Following Neoadjuvant Endocrine Therapy

BACKGROUND

Randomized clinical trials support deescalation of axillary surgery in breast cancer patients with low-volume axillary disease treated with a surgery-first approach. However, few data exist to guide axillary surgery following neoadjuvant endocrine therapy (NET). Therefore, we evaluated the extent and outcomes of axillary surgery in a contemporary cohort of NET patients, a treatment approach that has become particularly relevant during the coronavirus disease-19 (COVID-19) pandemic.

PATIENTS AND METHODS

We identified invasive breast cancer patients treated with NET between October 2008 and November 2019. Patients presenting with stage IV disease or recurrent disease were excluded. Statistical analyses were performed using chi-square, Fisher's exact, and Wilcoxon rank-sum tests.

RESULTS

194 invasive breast cancers in 186 patients (median age 66 years) were evaluated; 81 patients had breast-conserving surgery (BCS), while 113 underwent mastectomy. Eighty-four patients (43.3%) were biopsy-proven cN+ with 4/84 (4.8%) ypN0 following NET. Among cN+ patients, 14 (16.7%) had sentinel lymph node biopsy (SLNB) only, 27 (32.1%) had SLNB + axillary lymph node dissection (ALND), and 43 (51.2%) had ALND. Among 110 cN0 patients, 99 had axillary surgery with 28/99 (28.3%) ypN+: SLNB in 83 (75.5%), SLNB+ALND in 14 (12.7%), and ALND in 2 (1.8%). Among all ypN+ patients, 23/108 (21.3%) had SLNB alone: 18/43 (41.9%) of BCS and 5/65 (7.7%) mastectomy patients (p < 0.001). After median follow-up of 35 months, no regional recurrences were observed.

CONCLUSIONS

Among biopsy-proven cN+ NET patients, we observed deescalation of axillary surgery in selected patients, despite a low nodal pathologic complete response (pCR) rate, without nodal recurrences. These data suggest that patients with low-volume axillary disease treated with NET may be managed similarly to patients treated with a surgery-first approach.

Preoperative Serum Hypersensitive-c-Reactive-Protein (Hs-CRP) to Albumin Ratio Predicts Survival in Patients with Luminal B Subtype Breast Cancer

Objective

To evaluate the clinical prognostic significance of preoperative serum hypersensitive-c-reactive-protein (Hs-CRP) to albumin ratio (CAR) in patients with luminal B subtype breast cancer.

Methods

A total of 199 patients with luminal B subtype breast cancer enrolled in this study were analyzed retrospectively. The optimal cutoff value of CAR was performed by the receiver operating characteristic curve (ROC). The associations between luminal B subtype breast cancer and clinicopathological variables by CAR were performed by chi-square test. Kaplan–Meier and log rank method were used for survival analysis. The independent prognostic factors were determined by univariate and multivariate Cox’s proportional hazards regression model.

Results

The patients were divided into low CAR group (CAR<0.044) and high CAR group (CAR≥0.044) by ROC. CAR was the independent factor by univariate and multivariate analysis, and the mean DFS and OS in the low CAR group survived longer than those in the high CAR group (p<0.05). According to the endocrine therapy with aromatase inhibitors, the mean survival time of DFS and OS in the low CAR group was significantly higher than that in the high CAR group (p<0.05). Moreover, patients with pathological I+II stage survived longer than those with pathological III stage, and the mean survival time of DFS and OS in the low CAR group was significantly higher than that in the high CAR group (p<0.05). Patients without lymph vessel invasion survived longer than those with lymph vessel invasion (p<0.05), and the mean survival time of DFS and OS in low the CAR group was significantly higher than that in the high CAR group (p<0.05).

Conclusion

Preoperative CAR was significantly associated with survival and prognosis of breast cancer, and it can be used as a routine prognostic indicator to predict the prognosis of luminal B subtype breast cancer.

Highlights of the 17th St Gallen International Breast Cancer Conference 2021: customising local and systemic therapies

The 17th edition of the St Gallen International Breast Cancer Conference was held in March 2021 in an entirely virtual mode. More than 3,300 participants took part in this important bi-annual critical review of the ‘state of the art’ in the multidisciplinary care of early-stage breast cancer (BC). Seventy-four experts from all continents discussed and commented on the previously elaborated consensus questions as well as numerous interrogations on early-BC diagnosis and treatment asked by the audience. The theme of this year’s Conference was ‘Customising local and systemic therapies’. This paper summarises the results of the 2021 international panel votes as a quick news update. We discuss the most important issues on genetics, pathology, surgery, radiotherapy and systemic therapies presented and debated throughout the conference. We selected the topics based on applicability into the personalised care of BC patients and focused on questions that have a clear impact on our current clinical practice.

Learning from organisational changes in the management of breast cancer patients during the COVID-19 pandemic: Preparing for a second wave at a breast unit in northern Italy

Italy was the first western country to be hit by the initial wave of severe adult respiratory syndrome coronavirus 2 pandemic, which has been more widespread in the country's northern regions. Early reports showing that cancer patients are more susceptible to the infection posed a particular challenge that has guided our Breast Unit at Hub Hospital in Trento to making a number of stepwise operational changes. New internal guidelines and treatment selection criteria were drawn up by a virtual multidisciplinary tumour board that took into account the risks and benefits of treatment, and distinguished the patients requiring immediate treatment from those whose treatment could be delayed. A second wave of the pandemic is expected in the autumn as gatherings in closed places increase. We will take advantage of the gained experience and organisational changes implemented during the first wave in order to improve further, and continue to offer breast cancer management and treatment to our vulnerable patient population.

Neoadjuvant endocrine therapy in women with operable breast cancer: A retrospective analysis of real-world use

BACKGROUND

A retrospective study of the real-world use of neoadjuvant endocrine therapy (NET) is important for standardizing its role in breast cancer care.

MATERIALS AND METHODS

In a consecutive series of women with operable breast cancer who received NET for ≥28 days, NET objectives, NET outcomes, adjuvant chemotherapy use after NET, and survivals, were examined for the correlation with clinicopathological factors.

RESULTS

NET objectives were for surgery extent reduction in 49 patients, surgery avoidance in 31, and treatment until scheduled surgery in 8. The mean duration of NET was 349.5 (range, 34-1923), 869.8 (range, 36-4859), and 55.8 (range, 39-113) days in the above cohorts (success: 79.6%, 64.5%, and 100%), respectively, with significant difference. In patients of the former two cohorts, better progression-free survival was significantly correlated with stage 0 or I, ductal carcinoma in situ or invasive ductal carcinoma, ≥71% estrogen receptor (ER) positivity, and the surgery extent reduction cohort than the other counterparts. Postoperative chemotherapy use was significantly correlated with lymph node metastasis, a high Ki67 labeling index, lymphovascular invasion, and a high Preoperative Endocrine Prognostic Index, at surgery after NET. Better recurrence-free survival after surgery was significantly correlated with high ER expression after NET and high PgR expression before and after NET.

CONCLUSIONS

NET can help to reduce the surgery extent or to avoid surgery in women with breast cancer of early-stage, ductal carcinoma, or high ER expression. NET may also contribute to appropriate decision of postoperative systemic therapy to improve survivals.

Neoadjuvant Endocrine Therapy in Breast Cancer: Current Knowledge and Future Perspectives

In locally advanced (LA) breast cancer (BC), neoadjuvant treatments have led to major achievements, which hold particular relevance in HER2-positive and triple-negative BC. Conversely, their role in hormone receptor positive (HR+), hormone epidermal growth factor 2 negative (HER2-) BC is still under debate, mainly due to the generally low rates of pathological complete response (pCR) and lower accuracy of pCR as predictors of long-term outcomes in this patient subset. While administration of neoadjuvant chemotherapy (NCT) in LA, HR+, HER2- BC patients is widely used in clinical practice, neoadjuvant endocrine therapy (NET) still retains an unfulfilled potential in the management of these subgroups, particularly in elderly and unfit patients. In addition, NET has gained a central role as a platform to test new drugs and predictive biomarkers in previously untreated patients. We herein present historical data regarding Tamoxifen and/or Aromatase Inhibitors and a debate on recent evidence regarding agents such as CDK4/6 and PI3K/mTOR inhibitors in the neoadjuvant setting. We also discuss key issues concerning the optimal treatment length, appropriate comparisons with NCT efficacy and use of NET in premenopausal patients.

ESR1 Mutations Are Not a Common Mechanism of Endocrine Resistance in Patients With Estrogen Receptor-Positive Breast Cancer Treated With Neoadjuvant Aromatase Inhibitor Therapy

Introduction: Mutations in the ESR1 gene (ESR1m) are important mechanisms of resistance to endocrine therapy in estrogen receptor–positive (ER+) metastatic breast cancer and have been studied as a potential therapeutic target, as well as a predictive and prognostic biomarker. Nonetheless, the role of ESR1m as a possible mechanism of primary endocrine resistance, as well as whether it also occurs in tumors that are resistant to ET administered in early-stage disease as (neo)adjuvant, has not been adequately studied. In this study, we evaluated the prevalence of ESR1m in tumor samples from patients with ER+ breast cancer resistant to neoadjuvant aromatase inhibitor therapy.

Methods: We followed a prospective cohort of patients with ER+ HER2– stages II and III breast cancer treated with neoadjuvant endocrine therapy (NET). Tumor samples from patients with a pattern of primary endocrine resistance [defined as a Preoperative Endocrine Prognostic Index (PEPI) score of ≥4] were identified and analyzed for the presence of ESR1m.

Results: One hundred twenty-seven patients were included in the cohort, of which 100 (79%) had completed NET and underwent surgery. Among these patients, the PEPI score ranged from 0 to 3 in 70% (70/100), whereas 30% (30/100) had a PEPI score of 4 or more. Twenty-three of these patients were included in the analysis. ESR1 mutations were not identified in any of the 23 patients with early-stage ER+ breast cancer resistant to NET.

Discussion: Growing evidence supports the notion that there are different mechanisms for primary and secondary endocrine resistance. Our study suggests that ESR1 mutations do not evolve rapidly and do not represent a common mechanism of primary endocrine resistance in the neoadjuvant setting. Therefore, ESR1m should be considered a mechanism of acquired endocrine resistance in the context of advanced disease. Further research should be conducted to identify factors associated with intrinsic resistance to ET.

Analytical validation of a standardised scoring protocol for Ki67 immunohistochemistry on breast cancer excision whole sections: an international multicentre collaboration

AIMS

The nuclear proliferation marker Ki67 assayed by immunohistochemistry has multiple potential uses in breast cancer, but an unacceptable level of interlaboratory variability has hampered its clinical utility. The International Ki67 in Breast Cancer Working Group has undertaken a systematic programme to determine whether Ki67 measurement can be analytically validated and standardised among laboratories. This study addresses whether acceptable scoring reproducibility can be achieved on excision whole sections.

METHODS AND RESULTS

Adjacent sections from 30 primary ER⁺ breast cancers were centrally stained for Ki67 and sections were circulated among 23 pathologists in 12 countries. All pathologists scored Ki67 by two methods: (i) global: four fields of 100 tumour cells each were selected to reflect observed heterogeneity in nuclear staining; (ii) hot-spot: the field with highest apparent Ki67 index was selected and up to 500 cells scored. The intraclass correlation coefficient (ICC) for the global method [confidence interval (CI) = 0.87; 95% CI = 0.799-0.93] marginally met the prespecified success criterion (lower 95% CI ≥ 0.8), while the ICC for the hot-spot method (0.83; 95% CI = 0.74-0.90) did not. Visually, interobserver concordance in location of selected hot-spots varies between cases. The median times for scoring were 9 and 6 min for global and hot-spot methods, respectively.

CONCLUSIONS

The global scoring method demonstrates adequate reproducibility to warrant next steps towards evaluation for technical and clinical validity in appropriate cohorts of cases. The time taken for scoring by either method is practical using counting software we are making publicly available. Establishment of external quality assessment schemes is likely to improve the reproducibility between laboratories further.

Transgelin-2 expression in breast cancer and its relationships with clinicopathological features and patient outcome

BACKGROUND

Transgelin-2 is an actin-binding protein that is widely expressed in various tissues and organs of the body, and reportedly may participate in the development and progression of multiple cancers. However, the clinical significance of transgelin-2 still remains controversial. We, therefore, aimed to determine the expression of transgelin-2 in breast cancer as well as its correlation with the tumorigenesis, progression and prognosis of human breast cancer.

METHODS

We collected tissues of 58 breast cancer patients from our hospital and 1090 samples from The Cancer Genome Atlas (TCGA) database. X-tile software was used to divide the transgelin-2 mRNA expression level in the database, logistic regression model was used to identify independent factors influencing transgelin-2 mRNA expression, and then Cox regression and Kaplan-Meier analysis were used to find factors that influence survival of breast cancer.

RESULTS

Transgelin-2 was significantly overexpressed in breast cancer tissues from our hospital and receiver operating characteristic (ROC) curve indicated that transgelin-2 may have diagnostic value. Meanwhile, estrogen receptor (ER) was in inverse correlation with transgelin-2 protein and mRNA expression, and transgelin-2 expression was positively correlated with Ki67 in breast cancer tissues. Logistic regression model revealed that TNM stage, ER and progesterone receptor (PR) status were independent factors for transgelin-2 mRNA expression. Patients with high transgelin-2 mRNA expression showed a poor survival and the trend was statistically significant only in ER-negative patients.

CONCLUSIONS

Transgelin-2 was expressed significantly higher in breast cancer cells and correlated with some clinicopathological factors. High transgelin-2 expression might predict poor prognosis for ER-negative patients.

Efficacy and acceptability of neoadjuvant endocrine therapy in patients with hormone receptor-positive breast cancer: A network meta-analysis

BACKGROUND

The optimal sequence of endocrine therapy in a neoadjuvant setting for hormone receptor-positive (HR+) breast cancer is unclear. Our study evaluated the efficacy and acceptability of neoadjuvant endocrine therapy for HR+ breast cancer.

METHODS

We identified studies based on titles and abstracts that were published before 22 June 2018 in the following databases: PubMed, EMBASE, and the Cochrane Library. Eligible studies were randomised controlled trials with at least one arm that evaluated the effectiveness of one or a combination of anastrozole, letrozole, palbociclib, tamoxifen, fulvestrant, abemaciclib, everolimus, gefitinib, ribociclib, taselisib, and exemestane. We pooled effect sizes using the odds ratio (OR) and corresponding 95% credibility interval (95% CrI). The primary outcomes were response rate and treatment completion.

RESULTS

Our network meta-analysis included 3,306 participants and 16 eligible studies, which assessed 15 treatments. In terms of response rates, compared with letrozole combined therapy, tamoxifen was associated with a significant reduction in response rate (OR, 0.34; 95% CrI, 0.13-0.85; OR, 0.32; 95% CrI, 0.13-0.80; OR, 0.26; 95% CrI, 0.09-0.83; and OR, 0.30; 95% CrI, 0.09-0.96; for letrozole plus everolimus, letrozole plus taselisib, letrozole plus zoledronic acid, and letrozole plus lapatinib, respectively). Based on the surface under the cumulative ranking curves ranking, letrozole plus zoledronic acid was associated with the highest rate of response (87.6%), followed by letrozole plus lapatinib (85.2%), and letrozole plus taselisib (79.3%).

CONCLUSIONS

Ultimately, our study established that letrozole plus zoledronic acid may be an optimal treatment based on its current rank in a neoadjuvant setting for HR+ breast cancer.

Neoadjuvant endocrine therapy with exemestane followed by response-guided combination therapy with low-dose cyclophosphamide in postmenopausal patients with estrogen receptor-positive breast cancer: A multicenter, open-label, phase II study

Patients with estrogen receptor (ER)‐positive breast cancer are less likely to achieve a pathological complete response (pCR) with neoadjuvant chemotherapy. Neoadjuvant endocrine therapy may be more appropriate than neoadjuvant chemotherapy in these hormone‐sensitive patients. Most patients with ER‐positive breast cancer are postmenopausal, and therefore, generally older and less able to tolerate chemotherapy. We aimed to investigate the efficacy and safety of tailored neoadjuvant endocrine and chemoendocrine therapy for postmenopausal breast cancer patients. Untreated patients with primary invasive ER‐positive, HER2‐negative, stage I‐IIIA breast cancer, and Ki67 index ≤30% were enrolled. Patients received exemestane 25 mg/d for 12 weeks. Based on clinical response and change in Ki67 index, assessed at 8‐12 weeks, patients with complete response (CR), partial response (PR) with Ki67 index ≤5% after treatment, or stable disease (SD) with Ki67 index ≤5% before and after treatment were defined as responders. For the subsequent 24 weeks, responders continued exemestane monotherapy (group A), and nonresponders received exemestane 25 mg/d plus cyclophosphamide 50 mg/d (group B). The primary endpoint was clinical response at weeks 24 and 36. A total of 59 patients (median age, 69 years) started initial exemestane monotherapy. After exclusion of three patients who discontinued during this period, 56 remained enrolled to receive subsequent treatment. Clinical response rates (CR and PR) and 95% CI at weeks 24 and 36 were 85% (12/14; 57.2%‐98.2%) and 71% (10/14; 41.9%‐91.6%), respectively, in group A; and 54% (23/42; 38.7%‐70.2%) and 71% (30/42; 55.4%‐84.3%), respectively, in group B. At week 36, no significant difference was found in median Ki67 index between the groups (3.5% and 4.0%). There were no treatment‐related deaths. We found that clinical response comparable to that of responders was achieved in nonresponders after addition of cyclophosphamide to the initial endocrine therapy.