Impact of Post-Mastectomy Radiation Therapy for Sentinel Lymph Node Micrometastases in Early-Stage Breast Cancer Patients

Abstract

Background The association of radiotherapy with breast cancer survival in patients who underwent a mastectomy and had micrometastases in the sentinel lymph node is unclear. Material/Methods The survival benefit of radiotherapy was examined in patients with T0/1-T2N1mi breast cancer undergoing mastectomy plus sentinel lymph node biopsy (SLNB). Kaplan-Meier curves were employed for survival analysis and competing risk analysis, and a propensity score matching (PSM) cohort was enrolled to investigate whether such patients benefit from radiotherapy. Results We identified 2864 patients in the SEER database from 2004 to 2015. All eligible patients were divided into the radiotherapy and the no-radiotherapy cohorts. With the median follow-up of 53 months, 5-year breast cancer-specific survival (BCSS) was 94.4% vs 95.2% ( P =0.135), and 5-year overall survival (OS) was 91.2% vs 90.1% ( P =0.466) in the radiotherapy cohorts and no-radiotherapy cohorts, respectively. The results of the competing risk analysis showed a comparable 5-year cumulative incidence of breast cancer-specific death (BCSD) in the radiotherapy and no-radiotherapy groups (5.5% vs 4.7%, P =0.107) but a higher 5-year cumulative incidence of other causes of death (OCD) in the no-radiotherapy cohort (3.3% vs 5.3%, P =0.011). No significant difference was observed for BCSS or OS in the PSM cohort. Conclusions Radiotherapy has no benefit for patients with T0/1-T2 breast cancer undergoing mastectomy with N1mi disease on SLNB. This analysis provides evidence that radiotherapy may safely be omitted in this group of patients.

Development and Validation of Prediction Models for Sentinel Lymph Node Status Indicating Postmastectomy Radiotherapy in Breast Cancer: a Population-Based Study of 18 185 Women

“…Similar to most other nomograms for the prediction of axillary nodal status, it does not consider the size of the metastatic deposit. Previous trials have failed to prove any benefit of PMRT for patients with only micrometastatic deposit (≤2.0 mm) 42, 43 and micrometastatic disease is not included in the current guidelines concerning recommendations for PMRT 12–14 . Therefore, the presented Nomogram I was developed to predict ≥1 macro-SLNMs specifically.…”

Can Axillary Lymph Node Dissection be Omitted in Breast Cancer Patients with Metastatic Sentinel Lymph Nodes Undergoing Mastectomy? A Systematic Review and Meta‐Analysis of Real‐World Evidence

“…Complementary to the IBCSG 23–01 trial, our meta‐analysis demonstrated no OS difference when performing ALND in mastectomy patients with micrometastatic SLNs. Due to the minimal nodal burden and a low risk of NSLNM, patients with nodal micrometastases undergoing mastectomy are likely to be treated adequately with SLND only without ALND [22, 42].…”

The prognostic significance of further axillary dissection for sentinel lymph node micrometastases in female breast cancer: A competing risk analysis using the SEER database

“…In fact, the question of whether complete ALND is actually required for patients with micrometastasis is an important one because of the long-term prognostic risk of systemic recurrence and local failure associated with residual axillary disease in sentinel lymph node positive patients who elect not to have further axillary surgery, and Controversy still exists surrounding the best management of patients with SLN micrometastases, in terms of further axillary surgery or radiotherapy and/or systemic adjuvant treatment ( 3 , 8 , 36 ). Nevertheless, we were surprised to find that axillary treatment was not an independent factor affecting OS and BCSS, nor was radiotherapy, although many people supposed that ALND and axillary radiotherapy could be alternatives for patients with SLN micrometastases since they may reduce loco-regional recurrence ( 37 ).…”

“…Importantly, the relative reduction in the number of ALNDs performed over the last decade is supported by a large and growing evidence base ( 3 , 17 , 19 ). In addition, in view of the fact that micrometastases are likely to represent a lower risk of local and distant failure than macrometastases and that women could be spared the morbidity of ALND, at present further intervention for women with SLN micrometastases is primarily surgical treatment, rather than axillary radiotherapy ( 3 , 36 ). Additionally, since SLN micrometastases are most commonly confirmed following complete pathological assessment, any further axillary surgery needs to take place on a second occasion.…”

“…Additionally, since SLN micrometastases are most commonly confirmed following complete pathological assessment, any further axillary surgery needs to take place on a second occasion. Hence, whether radiotherapy can be safely avoided in patients with micrometastases remains unclear, and further studies are still needed to answer this question ( 36 , 38 ).…”