Postmastectomy radiation in breast cancer with one to three involved lymph nodes: ending the debate

Many trials in breast cancer have investigated various aspects of locoregional and systemic treatments. Combination of the results of these trials in a meticulous meta-analysis, as has been done several times by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG), fi lls the gaps in evidence and knowledge by conclusively showing signifi cant trends and diff erences. Following publication of the eff ect of radiotherapy after breast-conserving therapy, the EBCTCG now presents results for postmastectomy radiotherapy in The Lancet. The central issue is the role of postmastectomy radiotherapy in patients with one to three involved axillary lymph nodes, which is currently a matter of debate in many countries. Whereas the earlier results were essentially confi rmed in this report, we get more insight into the eff ect of the extent of lymph-node involvement, the number of examined axillary lymph nodes, and the use of adjuvant systemic therapy. Overall, postmastectomy radiotherapy improves locoregional disease-free survival, overall disease-free survival, and breast-cancer-specifi c survival for all patients with involvement of axillary lymph nodes, irrespective of the number of involved lymph nodes and of administration of adjuvant systemic therapy. This improvement is not only statistically signifi cant, but also clinically relevant. The proportional reductions in rates of recurrence and mortality were independent of the administration of systemic therapy. Whether this fi nding also applies to patients treated with more contemporary regimens remains to be seen. We need to continue evaluating results of the contemporary multidisciplinary approach in breast cancer to better understand the complex interaction between respective contributions of systemic and locoregional treatments to the fi nal outcome, including survival and toxic eff ects. As Punglia and colleagues pointed out, the contribution of improved locoregional control to survival depends on the eff ectiveness of systemic treatment. Punglia and colleagues’ bell-shaped curve, however, misses the component of metastatic risk of the primary tumour. Combining both, the infl uence of both the eff ectiveness of systemic therapy and metastatic risk of the primary tumour can be used to estimate the GS is President of the Association des Correspondants Auprès des Nations Unies.