Is it beneficial for patients with pT1-2N1M0 breast cancer to receive postmastectomy radiotherapy? An analysis based on RecurIndex assay

Biomarker-Directed Radiotherapy in Breast Cancer: A Narrative Review

Importance

Integration of molecular biomarker information into systemic therapy has become standard practice in breast cancer care. However, its implementation in guiding radiotherapy (RT) is slower. Although postoperative RT is recommended for most patients after breast-conserving surgery and, depending on risk factors, following mastectomy, emerging evidence has indicated that patients with low scores on gene expression signatures or selected clinical-pathological features may have very low local recurrence rates. This narrative review explored the potential of biomarker-directed personalized RT approaches, which may optimize treatment strategies and be associated with improved patient outcomes and experiences.

Observations

Distinctions between prognostic and predictive biomarkers were highlighted, emphasizing the importance of analytical and clinical validity in biomarker-based studies. Findings from studies investigating the prognostic and predictive value of various genomic signatures and immunohistochemical markers for guiding breast RT were presented. These included the Adjuvant Radiotherapy Intensification Classifier and the Profile for the Omission of Local Adjuvant Radiation, which have shown potential in predicting RT benefits. The genomic-adjusted radiation dose and role of tumor-infiltrating lymphocytes were also discussed. Ongoing clinical trials exploring the use of biomarkers in ductal carcinoma in situ and invasive breast cancer to refine RT decision-making were illustrated.

Conclusions and Relevance

The results of this narrative review suggest that evidence-based shared decision-making is crucial to optimize treatment according to the individual's predicted benefits and risks along with their personal preferences. Incorporation of biomarker-directed approaches in RT for breast cancer may hold promise for personalized treatment, potentially facilitating omission of RT for patients at low risk of recurrence, while identifying those who may benefit from intensified therapy. This personalized RT approach may be associated with improved clinical outcomes and quality of life and facilitate decision-making for people with breast cancer. However, there remains a need for robust clinical and analytical validation of biomarkers to ensure reliability and clinical utility for RT optimization.

Prognostic significance of ER-to-PR difference in ER+/HER2- early breast cancer

ER+/HER2- breast cancer is a common subtype of breast cancer. This study aimed to evaluate the prognostic value of ER-to-PR difference (EPD) in ER+/HER2- early breast cancer (EBC). A retrospective cohort study was conducted, including 3,340 ER+/HER2- EBC patients, divided into a training cohort of 2,873 patients and a validation cohort of 467 patients. The optimal EPD cutoff value for stratifying patients was determined using X-tile. Additionally, the prognostic value of EPD, when combined with other clinicopathological factors, was assessed using the Cox proportional hazards model and five traditional machine learning methods. The optimal cutoff value for EPD was determined as 10%, categorizing patients into EPD-low (ER-PR ≤ 10%) and EPD-high (ER-PR > 10%) expression groups. Patients with EPD-high tumors exhibited a poorer prognosis compared to those with EPD-low tumors. In the multivariate Cox model, EPD was identified as an independent prognostic factor for disease-free survival (DFS) (HR: 1.496, P = 0.004). Integrating EPD with clinicopathological parameters into a predictive model effectively predicts DFS in ER+/HER2- EBC patients. In the most effective CoxPH model, the area under the curve (AUC) values for predicting 3-year, 5-year, and 7-year DFS were 0.718, 0.702, and 0.701, respectively, in the WCH cohort, and 0.770, 0.739, and 0.743, respectively, in the FUSCC cohort. EPD may serve as a novel prognostic marker, allowing for the identification of a population with a poor prognosis in ER+/HER2- EBC, thereby aiding clinical decision-making.

RecurIndex-Guided postoperative radiotherapy with or without Avoidance of Irradiation of regional Nodes in 1-3 node-positive breast cancer (RIGAIN): a study protocol for a multicentre, open-label, randomised controlled prospective, phase III trial

INTRODUCTION

Postoperative radiotherapy in patients with breast cancer with one to three lymph node metastases, particularly within the pT1-2N1M0 cohort with a low clinical risk of local-regional recurrence (LRR), has incited a discourse surrounding personalised treatment strategies. Multigene testing for Recurrence Index (RecurIndex) model capably differentiates patients based on their level of LRR risk. This research aims to validate whether a more aggressive treatment approach can enhance clinical outcomes in N1 patients who possess a clinically low risk of LRR, yet a high RecurIndex-determined risk of LRR. Specifically, this entails postoperative whole breast irradiation combined with regional lymph node irradiation (RNI) following breast-conserving surgery or chest wall irradiation with RNI after mastectomy.

METHODS AND ANALYSIS

The RIGAIN (RecurIndex-Guided postoperative radiotherapy with or without Avoidance of Irradiation of regional Nodes in 1-3 node-positive breast cancer) Study is a multicentre, prospective, randomised, open-label, phase III clinical trial that is being conducted in China. In this study, patients with low clinical LRR risk but high RecurIndex-LRR risk are randomly assigned in a 1:1 ratio to the experimental group or the control group. In the experimental group, RNI is performed and the control group omits RNI. Efficacy and safety analyses will be conducted, enrolling a total of 540 patients (270 per group). The primary endpoint is invasive disease-free survival, and secondary endpoints include any first recurrence, LRR-free survival, distant metastasis-free survival, recurrence-free survival, overall survival, disease-free survival, breast cancer-specific mortality and assessment of patient quality of life. The study began in April 2023 and with a follow-up period of 60 months after the last participant completes radiation therapy.

ETHICS AND DISSEMINATION

The study was approved by the Ethics Committee of Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University (SYSKY-2022-097-02, V.3.1). It adheres to the Helsinki Declaration and Good Clinical Practice. Research findings will be submitted for publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04069884.

An Analysis of Clinical and Pathologic Features, RecurIndex Genomic Profiles, and Survival Outcomes in HER2-Low Breast Cancer

BACKGROUND

In recent years, breast cancer has become the most common cancer in the world, increasing women's health risks. Approximately 60% of breast cancers are categorized as human epidermal growth factor receptor 2 (HER2)-low tumors. Recently, antibody-drug conjugates have been found to have positive anticancer efficacy in patients with HER2-low breast cancer, but more studies are required to comprehend their clinical and molecular characteristics.

METHODS

In this study, we retrospectively analyzed the data of 165 early breast cancer patients with pT1-2N1M0 who had undergone the RecurIndex testing. To better understand HER2-low tumors, we investigated the RecurIndex genomic profiles, clinicopathologic features, and survival outcomes of breast cancers according to HER2 status.

RESULTS

First, there were significantly more hormone receptor (HR)-positive tumors, luminal-type tumors, and low Ki67 levels in the HER2-low than in the HER2-zero. Second, RI-LR (P = .0294) and RI-DR (P = .001) scores for HER2-low and HER2-zero were statistically significant. Third, within HER2-negative disease, HR-positive/HER2-low tumors showed highest ESR1, NFATC2IP, PTI1, ERBB2, and OBSL1 expressions. Fourth, results of the survival analysis showed that lower expression of HER2 was associated with improved relapse-free survival for HR-positive tumors, but not for HR-negative tumors.

CONCLUSIONS

The present study highlights the unique features of HER2-low tumors in terms of their clinical characteristics as well as their gene expression profiles. HR status may influence the prognosis of patients with HER2-low expression, and patients with HR-positive/HER2-low expression may have a favorable outcome.

Genetic Testing Enhances the Precision Diagnosis and Treatment of Breast Cancer

The contemporary comprehension of breast cancer has progressed to the molecular level. As a heterogeneous malignancy, conventional pathological diagnosis and histological classification could no longer meet the needs of precisely managing breast cancer. Genetic testing based on gene expression profiles and gene mutations has emerged and substantially contributed to the precise diagnosis and treatment of breast cancer. Multigene assays (MGAs) are explored for early-stage breast cancer patients, aiding the selection of adjuvant therapy and predicting prognosis. For metastatic breast cancer patients, testing specific genes indicates potentially effective antitumor agents. In this review, genetic testing in early-stage and metastatic breast cancer is summarized, as well as the advantages and challenges of genetic testing in breast cancer.

IMNI PRECISION trial protocol: a phase II, open-label, non-inferior randomized controlled trial of tailoring omission of internal mammary node irradiation for early-stage breast cancer

BACKGROUND

Since the publication of MA-20 and EORTC-22922 trials, chest wall (CW)/ whole breast (WB) irradiation + comprehensive regional nodal irradiation (RNI) with internal mammary node irradiation (IMNI) has been the standard adjuvant treatment for early-stage breast cancer (BC). However, one size does not fit all BC, and the risk of recurrence significantly varies among this patient population. In addition, whether all BC patients presented with one to three positive lymph nodes (pN1) could benefit from IMNI remains controversial. Thus, the optimal adjuvant RNI volume for early-stage BC with T1-2N1 remains undetermined.

METHODS

The IMNI PRECISION trial is a single institute, open-labeled, non-inferior, randomized controlled trial. A total of 214 clinically "high risk" BC patients which is characterized as having at least two of the five clinically adverse factors (age ≤ 40, three positive LN, T2 stage, grade 3 and Ki-67 index ≥ 14%), but genomic score "low risk" (the genomic score ≤ 44) N1 breast cancers are randomly assigned to omitting IMNI group (experimental group) or with IMNI (control group) with a 1:1 ratio. The primary endpoint of this trial is event-free survival, and secondary endpoints include overall survival and locoregional recurrence-free survival.

DISCUSSION

The IMNI PRECISION design allows promising clinical-genomic model to stratify the individualized risk of developing recurrence and guides the optimal RNI treatment for early-stage (pT1-2N1) BC patients. We anticipate that our results would provide high-level evidence to tailor IMNI according to individualized recurrence risk of BC.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT04517266 . Date of registration: August 18, 2020. Status: Recruiting.

RecurIndex assay as an aid for adjuvant chemotherapy decisions in HR-positive HER2-negative breast cancer patients

Background

Adjuvant chemotherapy is a major adjuvant treatment modality for hormonal receptor (HR)-positive and HER2-negative early breast cancer, but only 2%-20% of patients derive practical benefits. How to balance its potential benefits and risks becomes a challenging clinical problem. The purpose of this study was to assess whether RecurIndex assay could serve as an aid for adjuvant chemotherapy decisions in Chinese patients with HR-positive HER2-negative early breast cancer.

Methods

The tissue samples of pT1-2N0 HR-positive HER2-negative breast cancer from multiple centers were detected using RecurIndex assay, based on which the patients were assigned into low- and high-risk groups. The survival outcomes of low- and high-risk patients including those with and without adjuvant chemotherapy were compared, and the risk factors for recurrence and metastasis were identified.

Results

Totally 445 patients were eligible for analysis. By contrast to high-risk patients, low-risk patients represented better 7-year recurrence-free survival (RFS), distant recurrence-free survival (DRFS) and local recurrence-free survival (LRFS) rates. For low-risk patients, no significant differences were shown between those with and without adjuvant chemotherapy in 7-year RFS, DRFS and LRFS rates. These differences were also inapparent between high-risk patients with and without adjuvant chemotherapy. The multivariate model revealed high-risk patients had a significantly elevated risk of recurrence and metastasis than those at low risk.

Conclusion

HR-positive HER2-negative early breast cancer patients at low risk stratified by RecurIndex assay might be exempt from adjuvant chemotherapy. Whether adjuvant chemotherapy may derive survival benefits for high-risk patients still needs larger cohorts to verify.