Regional Nodal Irradiation After Breast Conserving Surgery for Early HER2-Positive Breast Cancer: Results of a Subanalysis From the ALTTO Trial

Executive Summary of the American Radium Society Appropriate Use Criteria: Regional Nodal Irradiation for Breast Cancer

OBJECTIVES

Recent literature has provided additional data to further individualize treatment recommendations on regional nodal irradiation (RNI) patient selection and delivery techniques, but controversies surrounding optimal RNI utilization remain, including radiation technique, modality selection, and internal mammary lymph node (IMN) inclusion. The American Radium Society (ARS) Breast Appropriate Use Criteria (AUC) Committee performed a systematic review and developed a consensus guideline to summarize recent data and provide evidence-based recommendations.

METHODS

A multidisciplinary panel comprised of 15 members representing radiation oncologists, medical oncologists, and surgical oncologists specializing in the treatment of breast cancer conducted an analysis of the medical literature from January 1, 2011 to April 1, 2024. Modified Delphi methodology was used to rate the appropriateness of treatments for variants across 3 key questions.

RESULTS

Patients with intermediate-risk breast cancer, such as limited nodal involvement or large primary tumor size, are reasonable candidates for RNI, although a subset of patients with overall favorable clinicopathologic features may be considered for treatment de-escalation. Data on the use of advanced radiation techniques for RNI were limited in scope and strength, and the panel agreed that careful patient selection is needed when using these tools. Evidence suggests that the IMN should be included when delivering RNI given the absolute benefit demonstrated in multiple randomized trials.

CONCLUSION

A systematic review and evidence-based summary of recommendations are provided in these consensus guidelines from the ARS Breast AUC Committee to provide current comprehensive guidance on the optimal management of non-metastatic breast cancer patients being considered for RNI.

Benefit of postoperative regional nodal irradiation in patients receiving preoperative systemic therapy with docetaxel/carboplatin/trastuzumab/pertuzumab for HER2-positive breast cancer

AIM

The role of regional nodal irradiation (RNI) after preoperative systemic treatment (PST) with targeted therapy for HER2-positive breast cancer remains uncertain. This study aimed to investigate the impact of RNI on locoregional recurrence (LRR) and disease-free survival (DFS) outcomes after docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP) for PST.

METHODS

We retrospectively analyzed 255 patients who were treated with six cycles of TCHP between 2016 and 2019. The patients were divided into four groups based on clinical nodal involvement: group A, with no nodal disease; group B, with axillary lymph node (AXL) level I; group C, with AXL level I with II/III; and group D, with supraclavicular or internal mammary nodes.

RESULTS

The RNI group had more advanced nodal disease (C/D) than the no RNI group (56.9 % vs. 6.8 %). With a median follow-up of 51.3 months, there were two (0.8 %), three (1.2 %), and 15 (5.9 %) local, regional, and distant metastases, respectively. LRR did not differ significantly according to the RNI (2.6 % vs. 1.0 %, p = 0.651). Group D had the most frequent distant metastases (17.5 %; p = 0.005). The 4-year DFS rate was 92.7 %, and DFS did not improve significantly after RNI (p = 0.074). When stratified by clinical nodal groups and pathological axillary response, RNI had no effect on LRR/DFS outcomes.

CONCLUSION

With a rare incidence of LRR, RNI did not significantly affect LRR or DFS in patients with HER2-positive breast cancer after with PST-TCHP. However, intensive systemic treatment is required for advanced diseases (C/D). Selective de-intensified RNI and intensified systemic treatment should be investigated in future studies.

The optimal regional irradiation volume for breast cancer patients: A comprehensive systematic review and network meta-analysis of published studies

Background

Currently, the optimal adjuvant regional nodal irradiation (RNI) volume for breast cancer (BC) remained controversial. We aimed to define the optimal RNI treatment volume for BC by using a comprehensive network meta-analysis (NMA) of published studies.

Materials and methods

PubMed, Embase, Medline, and Cochrane Central Register of Controlled Trials were searched from database inception to 30 May 2022. Studies assessing different adjuvant RNI volumes for BC were eligible for inclusion. The primary outcome was overall survival (OS), and secondary outcome was disease-free survival (DFS) and distant-metastasis-free survival (DMFS).

Results

A total of 29,640 BC patients from twenty studies were included. The pooled hazard ratio demonstrated that internal mammary node irradiation (IMNI) in BC patients significantly improved OS giving HR (hazard ratio) of 0.87 (95%CI: 0.83-0.91, p<0.001), DFS with HR of 0.78 (95%CI: 0.68-0.90, p<0.01), and DMFS with HR of 0.87 (95%CI: 0.79-0.97, p<0.01) when compared to controls. Sub-group analysis indicated that RNI with IMNI significantly improved OS (HR 0.87, 95%CI: 0.81-0.93, p<0.01), DFS (HR 0.65, 95%CI: 0.56-0.77, p<0.01), and DMFS (HR 0.90, 95%CI: 0.82-0.98, p=0.02) when compared to RNI without IMNI. NMA showed that CW/WB (chest wall/whole breast) + RNI with IMNI significantly improved DFS (HR 0.93, 95%CI: 0.86-1.00) and DMFS (HR 0.90, 95%CI: 0.81-0.99), but not for OS (HR 0.93, 95%CI: 0.84-1.03) when compared to CW/WB alone. Based on the analysis of the treatment ranking, CW/WB+RNI with IMNI appeared as the best treatment approach for BC patients.

Conclusions

Our pooled results demonstrated that RNI with IMNI yielded a significant survival advantage for BC patients. NMA showed that CW/WB+RNI with IMNI was the optimal radiation volume for BC patients.

Effect of the Nipple-Excising Breast-Conserving Therapy in Female Breast Cancer: A Competing Risk Analysis and Propensity Score Matching Analysis of Results Based on the SEER Database

Introduction

Due to the lack of randomized controlled trial, the effectiveness and oncological safety of nipple-excising breast-conserving therapy (NE-BCT) for female breast cancer (FBC) remains unclear. We aimed to explore and investigate the prognostic value of NE-BCT versus nipple-sparing breast-conserving therapy (NS-BCT) for patients with early FBC.

Methods

In this cohort study, data between NE-BCT and NS-BCT groups of 276,661 patients diagnosed with tumor–node–metastasis (TNM) stage 0–III FBC from 1998 to 2015 were retrieved from the Surveillance, Epidemiology, and End Results database. Propensity score matching analysis, Kaplan–Meier, X-tile, Cox proportional hazards model, and competing risk model were performed to evaluate the effectiveness and oncological safety for patients in NE-BCT and NS-BCT groups.

Results

A total of 1,731 (0.63%) patients received NE-BCT (NE-BCT group) and 274,930 (99.37%) patients received NS-BCT (NS-BCT group); 44,070 subjects died after a median follow-up time of 77 months (ranging from 1 to 227 months). In the propensity score matching (PSM) cohort, NE-BCT was found to be an adversely independent prognostic factor affecting overall survival (OS) [hazard ratio (HR), 1.24; 95% CI, 1.06–1.45, p=0.0078]. Subjects in NE-BCT group had similar breast-cancer-specific survival (BCSS) (HR, 1.15; 95%CI, 0.88–1.52, p=0.30) and worse other-causes-specific death (OCSD) (HR, 1.217; 95%CI, 1.002–1.478, p=0.048<0.05) in comparison with those in the NS-BCT group.

Conclusions

Our study demonstrated that the administration of NE-BCT is oncologically safe and reliable and can be widely recommended in clinics for women with non-metastatic breast cancer.

Comparison of Dose Distribution in Regional Lymph Nodes in Whole-Breast Radiotherapy vs. Whole-Breast Plus Regional Lymph Node Irradiation: An In Silico Planning Study in Participating Institutions of the Phase III Randomized Trial (KROG 1701)

Simple Summary

The purpose of the current in silico planning study is to compare radiation doses of whole-breast irradiation (WBI) and whole-breast plus regional lymph node irradiation (WBI+RNI) administered to the regional lymph nodes (RLN) in pN1 breast cancer. Twenty-four participating institutions were asked to create plans of WBI and WBI+RNI for two dummy cases. In all RLN regions including supraclavicular lymph node, axillary lymph node, and internal mammary lymph node, the radiation dose to the RLN was higher in WBI+RNI plan than WBI plan.

Abstract

The purpose of the current in silico planning study is to compare radiation doses of whole-breast irradiation (WBI) and whole-breast plus regional lymph node irradiation (WBI+RNI) administered to the regional lymph nodes (RLN) in pN1 breast cancer. Twenty-four participating institutions were asked to create plans of WBI and WBI+RNI for two dummy cases. To compare target coverage between the participants, an isodose line equal to 90% of the prescribed dose was converted to an isodose contour (contour_{90% iso})_. The relative nodal dose (RND) was obtained using the ratio of RLN dose to the target dose. The Fleiss’s kappa values which represent inter-observer agreement of contour_{90% iso} were over 0.68. For RNI, 6 institutions included axillary lymph node (ALN), supraclavicular lymph node (SCN), and internal mammary lymph node (IMN), while 18 hospitals included only ALN and SCN. The median RND between the WBI and WBI+RNI were as follows: 0.64 vs. 1.05 (ALN level I), 0.27 vs. 1.08 (ALN level II), 0.02 vs. 1.12 (ALN level III), 0.01 vs. 1.12 (SCN), and 0.54 vs. 0.82 (IMN). In all nodal regions, the RND was significantly lower in WBI than in WBI+RNI (p < 0.01). In this study, we could identify the nodal dose difference between WBI and WBI+RNI.

Impact of Regional Nodal Irradiation on the Outcomes of N1 Breast Cancer Patients Referred for Adjuvant Treatment: A Patient-Level Pooled Analysis of 2 Clinical Trials

PURPOSE

To evaluate the impact of regional nodal irradiation (RNI) among N1 operable breast cancer patients who underwent adequate axillary dissection and received adjuvant chemotherapy.

PATIENTS AND METHODS

This is a pooled analysis of 812 breast cancer patients referred for adjuvant systemic therapy in 2 prospective randomized studies: NCT00174655 (BIG 02/98) and NCT00312208 (BCIRG005). Overall survival was assessed according to whether patients received supraclavicular and/or internal mammary radiotherapy through Kaplan-Meier estimates. Univariate and multivariate analyses of variables affecting overall and relapse-free survival were performed through Cox regression analysis. Additionally, recurrence rates were analyzed according to regional irradiation patterns.

RESULTS

Regional relapse rates (after a median follow-up of 76 months) were 1.5% in both groups of patients who received or did not receive supraclavicular radiotherapy. The risk of regional recurrence was 0.7% in patients who received internal mammary node radiotherapy versus 1.6% in patients who did not receive internal mammary node radiotherapy. The following factors were associated with worse overall survival in multivariate Cox regression analysis: age < 40 years (P < .0001), > T1 stage (P = .003), and negative hormone receptor status (P = .002). Neither supraclavicular nor internal mammary radiotherapy was associated with improvement in overall or relapse-free survival in Cox regression analysis.

CONCLUSION

The current analysis does not endorse the routine use of supraclavicular or internal mammary radiotherapy among N1 operable breast cancer patients who have undergone adequate dissection of axillary lymph nodes and who have received standard adjuvant systemic therapy. Given the limited power and potential selection bias of the current analysis, further prospective studies are needed to tackle this research question.

Predictors of internal mammary lymph nodes (IMLN) metastasis and disease-free survival comparison between IMLN-positive and IMLN-negative breast cancer patients: Results from Western China Clinical Cooperation Group (WCCCG) database (CONSORT)

Limited studies performed a comprehensive assessment of risk factors for internal mammary lymph nodes (IMLN) metastasis, and disease-free survival (DFS) difference between IMLN-positive and IMLN-negative breast cancer (BC) patients undergoing IMLN dissection and systemic therapies was not clear.A retrospective study included 1977 BC patients from Western China Clinical Cooperation Group between January 2005 and December 2012. The impact of clinicopathological factors on the occurrence of IMLN metastasis was assessed in univariate and multivariate logistic regression analyses, and a nomogram (model) was constructed to predict the IMLN status. DFS difference was evaluated in univariate and multivariate Cox regression analyses between IMLN-negative and IMLN-positive patients, and univariate analysis was performed to compare DFS between individuals with high and low IMLN metastasis risk defined by proposed nomogram.Of 1977 enrolled patients, 514 cases underwent IMLN dissection and 1463 cases did not undergo IMLN irradiation or dissection. We found that initial disease symptoms and signs, mammographic calcification, tumor site, number of positive axillary lymph nodes (ALNs), American Joint Committee on Cancer pT stage, and human epidermal growth factor receptor 2 status were associated with IMLN metastasis (all P < .05). Those variables were included in nomogram, whose predictive ability was better than that of ALN classification (area under the curve: 0.82 vs 0.76, P < .001). Univariate cox proportional hazards model indicated that better DFS was observed in IMLN-negative patients than IMLN-positive group (hazard ratio [HR] = 1.87, 95% confidence interval [CI] = 1.05-3.34; P = .04), whereas no significant differences in DFS (HR = 0.99, 95% CI = 0.49-2.00; P = .97) were found after adjusting patient-, disease-, and treatment-related factors.Nipple inversion, mammographic calcification, larger tumor size, medial tumor site, negative HER-2 status, and more positive ALNs are independent risk factors for IMLN metastasis, and the individualized nomogram is a feasible tool to predict the status of IMLN. Equivalent DFS was found between positive and negative IMLN patients who all accepted IMLN dissection and systemic therapies.

Long-Term Impact of Regional Nodal Irradiation in Patients With Node-Positive Breast Cancer Treated With Neoadjuvant Systemic Therapy

PURPOSE

The impact of regional nodal irradiation (RNI) on locoregional recurrence (LRR) and any disease recurrence (DR) in women with node-positive breast cancer who receive neoadjuvant systemic therapy (NAT) is unknown.

METHODS AND MATERIALS

The impact of RNI on LRR and DR was estimated with the cumulative incidence method in 1289 women with stage II to III breast cancer with cytologically confirmed axillary metastases who received NAT between 1989 and 2007. Multicovariate Cox regression analysis was performed to examine the effect of RNI after accounting for other predictive and prognostic variables.

RESULTS

The median follow-up after definitive surgery was 10.2 years. Axillary pathologic complete response (pCR) was observed in 368 of 1289 patients (28.5%). On univariate analysis, axillary pCR reduced 10-year LRR risk from 9.7% to 4.8% (P = .006) and DR risk from 43.0% to 17.0% (P < .001). RNI was administered to 1080 of 1289 patients (83.8%). On univariate analysis, RNI did not affect 10-year LRR risk (no RNI, 9.4%; RNI, 8.1%; P = .62) or DR risk (no RNI, 31.3%; RNI, 36.5%; P = .16). On multicovariate analysis, RNI significantly reduced the risk of LRR (hazard ratio, 0.497; 95% confidence interval [CI], 0.279-0.884; P = .02) and DR (hazard ratio, 0.731; 95% CI, 0.541-0.988; P = .04) and showed a particularly strong reduction in risk of DR in patients with HER2+ disease who received trastuzumab (hazard ratio, 0.237; 95% CI, 0.109-0.517; P = .0003). A nomogram to predict 10-year LRR risk with and without RNI has been generated to assist clinicians in individualizing treatment decisions based on patient and disease characteristics and response to NAT.

CONCLUSIONS

Adjuvant RNI reduces risk of LRR and DR in patients with breast cancer with axillary metastases who receive NAT across subtypes and particularly decreases the risk of DR in HER2+ breast cancer treated with trastuzumab. Enrollment on the National Surgical Adjuvant Breast and Bowel Project B-51/Radiation Therapy Oncology Group 1304 protocol is encouraged to help determine whether RNI can be omitted in patients with axillary pCR to NAT.