Dr Philip Poortmans - Institute Verbeeten, Tilburg, The Netherlands, talks to ecancer at the 2013 European Cancer Congress.

Irradiation of the internal mammary and medial supraclavicular lymph nodes in stage I to III breast cancer: 10 years results of the EORTC Radiation Oncology and Breast Cancer Groups phase III trial 22922/10925.

Locoregional radiation therapy (RT) improves overall survival in patients with involved lymph nodes (LN). EORTC trial 22922-10925 investigates how much RT to the internal mammary and medial supraclavicular LN (IM-MS) contributes to this effect (Clinicaltrials.gov NCT00002851).

Eligible patients had involved axillary LN and/or a medially located primary tumour. Randomisation was to yes or no IM-MS RT to 50 Gy in 25 fractions. The final trial design aimed at detecting a 4% increase in 10-year overall survival (OS) (from 75 to 79%, HR=0.82) with 2-sided unadjusted Logrank test at the 5% significance level. Secondary endpoints are disease-free survival (DFS), metastases-free survival (MFS) and cause of death.

With a median follow-up of 10 years, postoperative RT to the IM-MS LN shows to improve overall, disease free and metastases free survival in patients with stage I-III breast cancer without an increase in non-breast cancer related mortality. Combined with the earlier report of good tolerance and limited toxicity up to 3 years, we advise radiation therapy to the internal mammary and medial supraclavicular lymph nodes for patients with involved axillary LN and/or a medially located primary tumour.

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