Fifteen-year results of the randomised EORTC trial 22922/10925 investigating internal mammary and medial supraclavicular (IM-MS) lymph node irradiation in stage I-III breast cancer.

504Background: EORTC trial 22922-10925 investigates whether internal mammary and medial supraclavicular (IM-MS) lymph nodes (LN) irradiation improves outcome for stage I-III breast cancer patients (Clinicaltrials.gov NCT00002851). The 10 years analysis showed an improvement of 3.0% in metastases free survival (p = 0.02) and of 1.6% in overall survival (p = 0.056). Toxicity was limited and no increased lethal side effects were seen. This is the second of 3 scheduled analyses, at 15-year follow-up. Methods: Eligible patients had involved axillary nodes and/or a medially located primary tumour. Randomisation was to irradiate or not the IM-MS. 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 Log-rank test at the 5% significance level. Secondary endpoints are disease-free survival (DFS), metastases-free survival (MFS) and cause of death. Two long-term analyses were planned, at respectively 15 and 20 years of follow-up. ...