[The multisegmental electron irradiation of the chest wall following ablative therapy of breast cancer].

PURPOSE

The paper describes the clinical aspects of postoperative irradiation of breast cancer using electron arc technique at the chest wall. The value of the treatment is assessed by long-term results concerning the rate of local recurrences and side effects. The advantages of the procedure are described with regard to physical and technical aspects.

PATIENTS AND METHODS

After mastectomy, 117 patients underwent and adjuvant radiotherapy of the chest wall by multisegmental electron rotation technique with energies between 4 and 14 MeV. The number and angular range of the segments as well as the energy of the electrons depended on the peculiar thickness of the chest wall. 25 times 2 Gy were applied within five weeks. The treatment planning is based on a patient model constructed from five CT-slices at least.

RESULTS

In four cases (3.4%) a local relapse and in one case (0.9%) a relapse in supraclavicular lymphatics was found. The recurrences appeared after an average period of 32 months. The mean observation time was 70 months. In 37 women (32%) distant metastases were seen after 29 months on an average. The five-year survival rate is 73.5%.

CONCLUSION

In comparison to usual techniques using photons the described method shows a more homogeneous dose distribution to the chest wall and a reduction of lung radiation exposure. The clinical result of this dose adaptation to the treatment volume is a lower rate of local relapses and of side effects, inclusive late reactions. It can be suggested that the efficiency of the procedure will be ameliorated in future using special electron compensators. This will result in a more favorable adaptation of dose distribution to the anatomical situation in regard to the cranio-caudal profile.