Breast-conserving therapy is better than mastectomy: Based on registry data from Norway

Paper I shows the benefit of BCT compared with mastectomy for women with early stage breast cancer. The adjust-ed analysis shows that women who underwent mastectomy had a HR of 1.64 (95% CI: 1.43-1.88) for breast cancer death compared to women who underwent BCT with RT. Paper II shows the survival benefit of BCT compared to mastectomy in stage T1N1N0 for women participating in the Norwegian mammography screening programme, but not for the other early stages of breast cancer. Women with T1N1N0 who underwent mastectomy had an HR of 2.91 (95% CI: 1.30–6.48) for breast cancer death compared to women who underwent BCT. This study indicates increased survival benefit of BCT compared with mastectomy with increasing severity of breast cancer. A better immune re-sponse in women undergoing BCT compared to mastectomy is discussed as a hypothesis. Detailed information on diagnosis, treatment and follow-up is needed to identify a cause that may explain the find-ings in Articles I and II. To increase and motivate fore data collection, article III describes how submitted data to the cancer registry can be used for European certification of hospitals that treat breast cancer in Norway