[Irradiation of lymph nodes areas in breast cancer]

Postoperative radiotherapy after breast surgery increases overall survival by decreasing the local relapse rate. The main site of relapse is the breast or the chest wall. The value of irradiation of the nodal basins is still discussed. It must be emphasized that nodal areas were systematically irradiated in the postmastectomy randomized trials demonstrating a benefit in survival for adjuvant radiotherapy. Axillary relapses are infrequent in case of complete axillary dissection; complementary irradiation could be proposed if the axillary dissection is incomplete or if there is a massive pathologic involvement of the axilla. Its main complication is lymphoedema, which remains the most frequent sequellae of the treatment of breast cancer. Supraclavicular irradiation is logical in case of axillary involvement. Internal mammary nodes are involved in 20 to 40% of the patients, depending of the axillary involvement and location of the tumor inside the breast. Irradiation of the internal mammary basin is difficult: optimal dosimetry required a CT-based simulation. Its benefit remains to be proved. Internal mammary nodes irradiation probably increased cardiovascular mortality. Sophisticated techniques are needed to spare the heart from irradiation. Two large randomized trials (French group, European Organization for Research and Treatment of Cancer [EORTC]) are currently evaluating the possible benefit of internal mammary irradiation.