Breast cancer: contribution of postoperative locoregional irradiation after mastectomy

A crucial step: Locoregional control is a crucial step in the achievement o f cancer cure. After mastectomy, locoregional irradiation (RT) dearly reduc es the incidence of chest wall and nodal relapse, especially with initial l esions measuring more than 5 an or with nodal involvement and/or large lymp hatic or vascular emboli. Clinical proof: Two recent randomized trials have confirmed the benefit of weil-adapted locoregional irradiation. in the Danish trial, including preme nopausal "high-risk" women treated by mastectomy and chemotherapy (CMF prot ocol), RT reduced locoregional relapses from 32% to 9% (p < 0.01) and incre ased the 10-year survival rate from 45% to 54% (p < 0.01). These results ar e now confirmed in postmenopausal women with an increase in the 10-year sur vival rate from 36% to 45% (p < 0.001). In the Canadian trial, locoregional relapses decreased from 25% to 13% and the 10-year survival rate increased from 56% to 65%. The meta-analysis published in 1995 by the EBCTCG showed only a modest benefit due to locoregional irradiation in breast cancer. How ever, when small trials and old trials started before 1970 were excluded be cause of imperfect methodologies and inadequate irradiation techniques, the benefit of "modern" radiotherapy appeared as significant in 7,840 patients selected in this way. In clinical practice: Thus, since locoregional irradiation can avoid some m etastatic evolution developed only after "local" or "nodal" relapse, it mud be integrated into a multidisciplinary strategy. Nevertheless, this treatm ent must be safe. This can be achieved with new irradiation techniques incl uding the definition of anatomical volumes and previsional dosimetry. The m ost important point concerns the treatment of internal mammary nodes, espec ially when previous chemotherapy including anthracyclines has been performe d. The use of a direct field, with at least 40% of the dose delivered by el ectrons in an alternating scheme is recommended to ensure veri, good protec tion of the heart and lungs.