The affected breast (with the index lesion) and associated lymphatic drainage will be treated according to the treating physician decision. The contralateral breast will be treated with 2 tangent fields, using 1.8-2 Gy/fx to a total dose of 50-50.4 Gy. The whole breast will be treated according to traditional guidelines and as described in the RTOG/NSABP B39 study. The heart should be completely blocked for left sided breasts, included lung tissue should be reduced to minimum. No overlapping field is allowed on the skin between the two breast fields in the midline. Maximal dose should not exceed 110%.