Optimizing treatment of low risk breast cancer patients

Standard of care for most women with early stage breast cancer is nowadays breast conserving therapy, which consists of a wide local excision of the tumor followed by adjuvant radiotherapy to the breast. This standard approach for the treatment of all breast cancer patients is under debate especially in elderly low risk breast cancer patients. Several clinical and histopathological factors, such as for example young age and high proliferation rate, are known to be predictors for local recurrence after breast conserving therapy. Part of this thesis focuses on preoperative partial breast irradiation as a method to treat selected low risk breast cancer patients with less extensive treatment. The first results indicate that this is a promising technique. The last part of this thesis focuses on the outcome of patients treated in the Netherlands Cancer Institute with breast conserving therapy over a period of 28 years. The treatment outcome was excellent with a 5- and 10 years ipsilateral breast tumor recurrence incidence of 2 and 5%. A selection of patients with very low risk on local recurrence had a lower risk to develop distant metastases and had better overall survival. This low risk group probably was over treated with the standard local treatment. This supports the need for better identification tools for patients who can be safely treated by reducing or omitting radiotherapy.