Radiotherapy to the conserved breast, chest wall, and regional nodes: is there a standard?

The role of radiotherapy in the treatment of breast cancer has changed considerable during the last two decades. It has now become the standard part of the breast-conserving procedure, as well as in patients who underwent mastectomy with T3+tumor and/or 4 or more positive lymphnodes in axilla.

Improvements are seen in the postmastectomy radiotherapy area by delivering better treatment techniques herewith avoiding treatment of the heart and lungs in order to optimize the improvement of local control and the significant improvement in survival. Indications exist that the largest impact of postmastectomy radiotherapy on survival is mostly seen in patients with minimal tumorload, i.e. small tumors and/or 1 or 2 positive lymphnodes.

In several clinical trials, it was shown that the relapse rate in the ipsilateral breast is reduced with a HR of 4 if whole breast irradiation is given after tumorectomy. The update of the Oxford meta-analysis demonstrated that this improvement in local control has also led to an improved survival in these patients. More information is recently gained on the required radiation dose in breast-conserving therapy. Especially patients less than 50 years of age have to be treated with a high radiation dose, 50 + 16 Gy boost, while a dose of 50 Gy in 5 weeks seems sufficient for patients older than 50 years, who have a microscopically complete excision. Further optimization of the radiotherapy technique is found in imaged guided approaches and intensity modulated radiotherapy. Combining these efforts allows for a more precise delivery of the radiation dose to a limited volume, so that the side effects like fibrosis will be reduced.

Partial breast irradiation, instead of whole breast irradiation, is now being tested in a few randomized trials. Although this approach may be useful in certain patients groups, it still cannot be accepted as standard treatment, as no proper selection criteria exist and no long-term follow-up data have been presented.