The effect of postmastectomy radiation therapy on high-risk patients with T1-2N0 breast cancer

Breast Cancer Tumor Board: A Radiologist's Guide to Postmastectomy Radiation Therapy

Radiation therapy represents a pillar in the current management of breast cancer. Historically, postmastectomy radiation therapy (PMRT) has been administered only in patients with locally advanced disease and a poor prognosis. These included patients with large primary tumors at diagnosis and/or more than three metastatic axillary lymph nodes. However, during the past few decades, several factors have prompted a shift in perspective, and recommendations for PMRT have become more fluid. Guidelines for PMRT in the United States are outlined by the National Comprehensive Cancer Network and the American Society for Radiation Oncology. Because evidence to support performing PMRT is frequently discordant, the decision to offer radiation therapy often requires team discussion. These discussions are usually held in multidisciplinary tumor board meetings in which radiologists play a pivotal role by providing critical information such as the location and extent of disease. Breast reconstruction after mastectomy is optional and is safe in cases in which the patient's clinical status allows it. The preferred method in the setting of PMRT is autologous reconstruction. If this is not possible, then a two-step implant-based reconstruction is recommended. Radiation therapy does involve a risk of toxicity. Complications can be seen in acute and chronic settings and range from fluid collections and fractures to radiation-induced sarcomas. Radiologists have a key role in detecting these and other clinically relevant findings and should be prepared to recognize, interpret, and address them. ^© RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Validation of a prognostic scoring system for postmastectomy locoregional recurrence in breast cancer

Background

To date, it remains unclear which patients with breast cancer (BC) benefit from post-mastectomy radiotherapy (PMRT). Cheng et al. developed and validated a scoring system based on 4 prognostic factors for locoregional recurrence (LRR) to identify patients in need for PMRT. These factors include age, estrogen receptor status, lymphovascular status and number of affected axillary lymph nodes.

Purpose

To validate the scoring system for LRR in BC developed by Cheng et al. by using an independent BC database.

Methods and materials

We retrospectively identified 1989 BC cases, treated with mastectomy (ME) with or without PMRT at the University Hospitals Leuven between 2000 and 2007. The primary endpoint was 5-year locoregional control rate with and without PMRT, according to the LRR score.

Results

Median follow-up time was 11.4 years. After excluding patients with missing variables 1103 patients were classified using the LRR scoring system: 688 (62.38%) patients were at low risk of recurrence (LRR score 0–1), 335 (30.37%) patients were at intermediate risk of recurrence (LRR score 2–3) and 80 (7.25%) patients were at high risk of recurrence (LRR score ≥4). 5-year locoregional control rates with and without PMRT were 99.20% versus 99.21% (p = 0.43) in the low-risk group; 98.24% versus 85.74% (p < 0.0001) in the intermediate-risk group and 96.87% versus 85.71% (p = 0.10) in the high-risk group respectively.

Conclusion

Our validation of the LRR scoring system suggests it can be used to point out patients that would benefit from PMRT. We recommend further validation of this scoring system by other independent institutions before application in clinical practice.

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Post-mastectomy radiotherapy.

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Scoring system by Cheng et al.

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Based on 4 factors.

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Age, estrogen receptor, lymphovascular status, affected axillary lymph nodes.

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Intermediate and high-risk patients could benefit from post-mastectomy radiotherapy.