Oral Presentation Joint 2016 COSA and ANZBCTG Annual Scientific Meeting

Regional nodal radiation therapy (rt) in early stage breast cancer (#116)

Sue Pendlebury 1
  1. St Vincent’s Hospital, Sydney, Sydney, NSW, Australia

The Early Breast Cancer Trialists Collaborative Group (EBCTCG) publication, 2005 confirmed that RT not only reduces local recurrence, but also confers a survival advantage.  That publication shows one additional survivor at 20 years for every 1.5 first recurrences prevented at 10 years.  RT roughly halves first recurrence proportionately with a resulting reduction in mortality of 15%.  The absolute reduction in breast cancer mortality at 20 years was 7.9% in women with 1-3 positive nodes and the relative risk of dying from breast cancer was 0.80 (95% CI 0.67 to 0.95; P=0.01) with similar results for patients with 4 or more nodes positive.  Two randomized trials published in 2015, one from EORTC and the other MA.20 study demonstrated advantages for patients who underwent regional nodal irradiation.  In general the patients in these trials had fewer than 4 nodes involved.  In MA.20 LLR improved from 92.2%-95.2% at 10 years (P=0.009); and DFS improved from 77%-82% at 5 years.  Both studies addressed the value of the addition of supraclavicular and Internal Mammary Chain RT although neither could assess the independent value of the IMC RT.  Huang (2008) published that the risk of internal mammary chain disease increased with increasing axillary nodal disease and with central and medial tumour location.  A population-based Cohort study from Denmark has shown an OS benefit of 3.7% when IMC RT is added.  This benefit was greatest when the risk of IMC involvement was highest. It is difficult reconciling these benefits, with the results of Z0011 in which patients with Sentinel Lymph Node positivity were randomized to completion Axillary dissection or not with no difference in either OS or local control at 6.3 years follow up. With such divergent data sets, indications for regional lymph node RT have become controversial.  The additional of regional nodal fields increases treatment complexity.  The data for hypofraction in this setting is less certain and so usually commits patients to longer courses of treatment and increased toxicity that includes pneumonitis, lymphoedema, heart disease and second malignancy.