[Breast cancer: value of postoperative locoregional irradiation following mastectomy].
A CRUCIAL STEP: Locoregional control is a crucial step in the achievement of cancer cure. After mastectomy, locoregional irradiation (RT) clearly reduces the incidence of chest wall and nodal relapse, especially with initial lesions measuring more than 5 cm or with nodal involvement and/or large lymphatic or vascular emboli.
Two recent randomized trials have confirmed the benefit of well-adapted locoregional irradiation. In the Danish trial, including premenopausal "high-risk" women treated by mastectomy and chemotherapy (CMF protocol), RT reduced locoregional relapses from 32% to 9% (p < 0.01) and increased the 10-year survival rate from 45% to 54% (p < 0.01). These results are now confirmed in postmenopausal women with an increase in the 10-year survival 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. However, when small trials and old trials started before 1970 were excluded because of imperfect methodologies and inadequate irradiation techniques, the benefit of "modern" radiotherapy appeared as significant in 7,840 patients selected in this way.


CONCLUSIONS
Thus, since locoregional irradiation can avoid some metastatic evolution developed only after "local" or "nodal" relapse, it must be integrated into a multidisciplinary strategy. Nevertheless, this treatment must be safe. This can be achieved with new irradiation techniques including the definition of anatomical volumes and previsional dosimetry. The most important point concerns the treatment of internal mammary nodes, especially when previous chemotherapy including anthracyclines has been performed. The use of a direct field, with at least 40% of the dose delivered by electrons in an alternating scheme is recommended to ensure very good protection of the heart and lungs.
Cutuli
B
B
Centre de Radiothérapie et Oncologie, Polyclinique de Courlancy, Reims.
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D017024:Chemotherapy, Adjuvant; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D015182:Lymphatic Irradiation; D008207:Lymphatic Metastasis; D015411:Mastectomy, Modified Radical; D015412:Mastectomy, Segmental; D008875:Middle Aged; D018714:Radiotherapy, Adjuvant; D016032:Randomized Controlled Trials as Topic; D015996:Survival Rate