Can internal mammary lymph nodes irradiation bring survival benefits for breast cancer patients? A systematic review and meta-analysis of 12,705 patients in 12 studies

Sicong Jia,Xuejuan Duan,Jie Kong,Dongxing Shen,Yuguang Shang,Zhikun Liu,Huina Han,Chenguang Zhao,Jun Zhang,Longyu Zhu

doi:10.1186/s13014-021-01772-y

Abstract

ObjectiveTo evaluate the effect of prophylactic irradiation of internal mammary lymph nodes in breast cancer patients.MethodsThe computer searched PubMed, EMBASE, Web of science, CNKI, Wanfang Medical Network, the Chinese Biomedical Literature Database to find clinical studies on internal mammary lymph node irradiation (IMNI) in breast cancer. The quality of the included literature was evaluated according to the Newcastle–Ottawa scale. Stata14 software was used for meta-analysis.ResultsA total of 12,705 patients in 12 articles were included for meta-analyzed. Compared with patients who unirradiated internal mammary lymph nodes (non-IMNI), the risk of death for patients after IMNI was reduced by 11% (HR 0.89, 95% CI 0.79–1.00, P = 0.0470); DFS of group mixed N+ patients (high risk group) was significantly improved after IMNI (HR 0.58, 95% CI 0.49–0.69, P < 0.001). Further subgroup analysis shows that compared with non-IMNI, DFS was significantly increased in N1or ypN1 subgroup (HR 0.65, 95% CI 0.49–0.87, P = 0.003) and N2or ypN2 subgroup (HR 0.51, 95% CI 0.37–0.70, P < 0.001) after IMNI, but there was no statistical difference in DFS between the IMNI and non-IMNI groups in N0 subgroup (HR 1.02 95% CI 0.87–1.20, P = 0.794) and N3 or ypN3 subgroup (HR 0.85, 95% CI 0.49–1.45, P = 0.547). No serious incidents were reported in all the included studies, and most of the acute and late side effects were mild and tolerable.ConclusionUnder modern radiotherapy techniques, IMNI can safely and effectively bring clinical benefits to N1–2 breast cancer patients, but its role in N0, N3 breast cancer patients remains to be further studied.

Highlights

Breast cancer is the most common malignant tumor among women in the world
Two classic randomized clinical studies, MA.20 [11] and EORTC22922-10925 [12], were excluded because they discussed Regional lymph node irradiation (RNI) or not, which was not completely consistent with our studied on internal mammary lymph nodes irradiation (IMNI) or not
Compared with patients who unirradiated internal mammary lymph nodes, the risk of death for patients after IMNI was reduced by 11% (HR 0.89, 95% confidence limits (CI) 0.79– 1.00, P = 0.047) (Fig. 2a)

Summary

Introduction

Breast cancer is the most common malignant tumor among women in the world. The number of its new cases is up to 2.08 million every year, and the incidence rate is still on the rise, which is a serious threat to women’s health [1]. The improvement of imaging technology making the detection rate of IMLNs metastasis has been significantly raised [8]; the rapid development of systemic treatment has greatly reduced the risk of distant metastasis [9]; technological and technical improvements in modern radiotherapy, such as IMRT or VMAT, have become widespread available in clinical practice, allowing respect 3D-CRT: a better dose distribution within the target volume (in terms of homogeneity) and a reduction in high doses to healthy tissues and organs at risk [10] These changes may allow patients to benefit more from IMNI. This study included the literature on whether or not IMLNs were irradiated as an intervention measure to conduct meta-analysis, in an attempt to provide a reliable basis for the treatment of breast cancer patients

Methods

Results

Discussion

Conclusion