A chronological homogeneous series of 467 breast cancers has been treated from 1969 to 1974 by tumorectomy followed by irradiation at curative doses: 75 Gy over a period of 7.5 weeks (60 Gy by telecesium and 25 Gy by accelerated electrons). The tumors were exclusively T1 T2/N0 and N1 according to the UICC classification. Symptom-free survival for more than 5 years was achieved in 80% of the cases. Survival was of 88% in the case of T1/N0 tumors and conservation of the breast with a good esthetic result was obtained in 90% (only 2 % invalidating sequelae from radiotherapy). These results could be maintained at 10 years with a survival rate of 77%. In order to achieve maximum security in the supervision of irradiated breast cancers, clinical tests, infrared thermography and radiology should be systematically used. Each method makes approximately 10% of errors, either by excess of by default; combination of these three methods reduces these errors by 4 in either way. One can thus intervene in time in the case of nonsterilized tumors (at about the 10th month) or in the case of a recurrence (at about the 30th month); 60% survival of more than 5 years will then be obtained by surgery.