The use of Breast Conserving Surgery (BCS) followed by radiotherapy (BSC-RT) in pT1 ( 2cm, positive clinical nodes and medium hospital size decreased the chance of BCS. For BCS-RT the same factors and negative pathological nodes decreased the chance of BCS-RT. Between regions large differences were seen. Cancer registry data are useful to monitor the guideline implementation strategies. Multidisciplinary treatment planning, surgeon and patient education could increase the use of BCS combined with RT in all age groups.