Radiotherapy of the lymphatic drainage pathways in breast carcinoma: time for a reassessment

Abstract

Background The treatment administered for regional lymph nodes has altered dramatically in recent years. The state of the evidence on radiotherapy has also substantially improved and a reassessment is required. Materials and results Randomized studies are available on axillary surgery versus radiotherapy (AMAROS); on refraining from axillary dissection after a positive sentinel node (SN) when radiotherapy is planned (ACOSOG Z0011); and on adjuvant radiotherapy of the regional lymph nodes (LNs). ACOSOG Z0011 shows that refraining from axillary dissection is possible even when there are one or two positive SNs. The meta-analysis of the studies on adjuvant radiotherapy for the regional LNs (EORTC, Canadian, and French studies) shows a significant survival benefit with radiotherapy, and a Danish cohort study has confirmed this result. The reduction in breast cancer–specific mortality in these studies was partly based on a “systemic” effect of regional radiotherapy, with a reduction in the rate of distant metastases. Conclusions The principle applying in surgical treatment of the axilla is “less is not worse.” By contrast, the principle applying in radiotherapy of the regional lymph nodes is “more may be better in some circumstances.” There is as yet no clear explanation for the discrepancy between these two findings. An immunological effect (through immunogenic cell death due to irradiation) has been discussed. Further research is needed on which patients are today capable of benefiting from regional radiotherapy.