[Controversy about internal mammary chain irradiation in breast cancer]

Irradiation of lymph nodes areas after surgery of breast cancer, and specifically of the internal mammary chain, is an open question, frequently discussed. Three randomised trials (French, European-EORTC, Canadian) have been recently published or presented. The French trial did not show any benefit for internal mammary chain irradiation, but it was probably underpowered. The EORTC and Canadian trials demonstrated an improvement in overall survival after lymph nodes irradiation, including the internal mammary chain. The absolute benefit is 1.6% (hazard ratio-0.88 in a recent meta-analysis). Because this benefit is limited, it is important to define the characteristics of the patients who may benefit from this irradiation. Analyses of the randomized trials are not complete, and it is difficult at this moment to accurately define this population. However, cardiac and pulmonary toxicity of lymph nodes irradiation is well known. For each patient, evaluation of the potential late toxicity must be evaluated and so an accurate dosimetry for critical organs must be performed: the indication of internal mammary chain irradiation depends of the benefit/risk ratio.