Trends in the Application of Postmastectomy Radiotherapy for Breast Cancer With 1 to 3 Positive Axillary Nodes and Tumors ≤5 cm in the Modern Treatment Era: A Retrospective Korean Breast Cancer Society Report

Variation in Rates of Post-Mastectomy Radiotherapy Among Women with Early Invasive Breast Cancer in England and Wales: A Population-Based Cohort Study

AIMS

This study examined whether patterns of post-mastectomy radiotherapy (PMRT) among women with early invasive breast cancer (EIBC) varied within England and Wales and explored the role of different patient factors in explaining any variation.

MATERIALS AND METHODS

The study used national cancer data on women aged ≥50 years diagnosed with EIBC (stage I-IIIa) in England and Wales between January 2014 and December 2018 who had a mastectomy within 12 months of diagnosis. A multilevel mixed-effects logistic regression model was used to calculate risk-adjusted rates of PMRT for geographical regions and National Health Service acute care organisations. The study examined the variation in these rates within subgroups of women with different risks of recurrence (low: T1-2N0; intermediate: T3N0/T1-2N1; high: T1-2N2/T3N1-2) and investigated whether the variation was linked to patient case-mix within regions and organisations.

RESULTS

Among 26 228 women, use of PMRT increased with greater recurrence risk (low: 15.0%; intermediate: 59.4%; high: 85.1%). In all risk groups, use of PMRT was more common among women who had received chemotherapy and decreased among women aged ≥80 years. There was weak or no evidence of an association between use of PMRT and comorbidity or frailty, for each risk group. In women with an intermediate risk, unadjusted rates of PMRT varied substantially between geographical regions (range 40.3-77.3%), but varied less for the high-risk (range 77.1-91.6%) and low-risk groups (range 4.1-32.9%). Adjusting for patient case-mix reduced the variation in regional and organisational PMRT rates to a small degree.

CONCLUSIONS

Rates of PMRT are consistently high across England and Wales among women with high-risk EIBC, but variation exists across regions and organisations for women with intermediate-risk EIBC. Effort is required to reduce unwarranted variation in practice for intermediate-risk EIBC.

Risk of Lymphedema Following Contemporary Treatment for Breast Cancer: An Analysis of 7617 Consecutive Patients From a Multidisciplinary Perspective

OBJECTIVE

The aim of this study was to identify the comprehensive risk factors for lymphedema, thereby enabling a more informed multidisciplinary treatment decision-making.

SUMMARY BACKGROUND DATA

Lymphedema is a serious long-term complication in breast cancer patients post-surgery; however, the influence of multimodal therapy on its occurrence remains unclear.

METHODS

We retrospectively collected treatment-related data from 5549 breast cancer patients who underwent surgery between 2007 and 2015 at our institution. Individual radiotherapy plans were reviewed for regional nodal irradiation (RNI) field design and fractionation type. We identified lymphedema risk factors and used them to construct nomograms to predict individual risk of lymphedema. Nomograms were validated internally using 100 bootstrap samples and externally using 2 separate datasets of 1877 Asian and 191 Western patients.

RESULTS

Six hundred thirty-nine patients developed lymphedema during a median follow-up of 60 months. The 3-year lymphedema incidence was 10.5%; this rate increased with larger irradiation volumes (no RNI vs RNI excluding axilla I-II vs RNI including axilla I-II: 5.7% vs 16.8% vs 24.1%) and when using conventional fractionation instead of hypofractionation (13.5% vs 6.8%). On multivariate analysis, higher body mass index, larger number of dissected nodes, taxane-based regimen, total mastectomy, larger irradiation field, and conventional fractionation were strongly associated with lymphedema (all P < 0.001). Nomograms constructed based on these variables showed good calibration and discrimination internally (concordance index: 0.774) and externally (0.832 for Asian and 0.820 for Western patients).

CONCLUSIONS

Trimodality breast cancer treatment factors interact to promote lymphedema. Lymphedema risk can be decreased by deintensifying node dissection, chemotherapy regimen, and field and dose of radiotherapy. Deescalation strategies on a multidisciplinary basis might minimize lymphedema risk.

Real-world impact of postmastectomy radiotherapy in T1-2 breast cancer with one to three positive lymph nodes

Background

The utility of postmastectomy radiotherapy (PMRT) in breast cancer patients with T1-2 (tumor size ≤5 cm) and N1 (one to three lymph nodes involved) disease remains controversial. The aim of this population-based study was to investigate the effectiveness of PMRT in this patient subset in the current clinical practice.

Methods

We included T1-2N1 breast cancer patients treated with mastectomy from 2004 to 2012 using the data form the Surveillance, Epidemiology, and End Results program. The association of PMRT administration with breast cancer-specific survival was determined using multivariable Cox analysis.

Results

We identified 10,248 patients of this study, including 3,725 (36.3%) received PMRT and 6,523 (63.7%) patients did not receive PMRT. Use of PMRT showed increase from 2008 onward; the percentage of patients receiving PMRT was 30.6% in 2004 and was 47.1% in 2012 (P<0.001). Patients diagnosis after 2008, aged <50 years, high tumor grade, T2 stage, and ≥2 positive lymph nodes were independently related to PMRT receipt. Multivariate analysis indicated that PMRT was not related to better breast cancer-specific survival compared to those without PMRT both before (P=0.186) and after propensity score matching (P=0.137).

Conclusions

In breast cancer with T1-2N1 disease, PMRT does not appear to improve survival in the era of modern systemic therapy.

Meeting Highlights: The Second Consensus Conference for Breast Cancer Treatment in Korea

The Korean clinical practice guideline recently developed by the Korean Breast Cancer Society to address the national clinical situation is currently under revision ahead of a seventh recommendation. A second consensus conference was held to further develop this guideline by soliciting opinions regarding important issues related to surgery, radiotherapy, and medical oncology. Several issues were discussed, and the discussion progressed to pros and cons in the context of cases in various clinical situations. The panels discussed and voted on issues regarding surgical treatment for non-axillary regional lymph nodes, regional nodal irradiation of pN1 disease, and ovarian functional suppression (OFS) as an adjuvant treatment in premenopausal patients with hormone receptor-positive breast cancer. Regarding the surgical treatment of non-axillary regional lymph node, most panelists agreed with the recommendation of preoperative chemotherapy and postoperative radiotherapy for patients with biopsy-diagnosed metastases, whereas surgery or radiotherapy of non-axillary regional lymph nodes was suggested for clinical partial responders. Discussions on radiotherapy addressed the need for adjuvant radiotherapy and radiation field of regional lymph node in the context of various N1 breast cancer cases. The participants reached a consensus to recommend that N1 patients should receive regional nodal irradiation for a large tumor burden (e.g., three positive nodes, perinodal extension, or large primary tumor). Finally, the panels favored OFS in addition to endocrine therapy for premenopausal women with high risk factors such as a large tumor size, involvement of more than three nodes, and a high histologic grade.