Background: Studies have revealed variations in breast cancer survival between different counties in Norway. This study describes trends in surgical treatment of ductal carcinoma in situ (DCIS) and breast cancer in Norway, over time and by county.
Material and method: Information about surgical treatment, age and county for 3,915 women with DCIS and for 54,732 women with breast cancer, diagnosed in the periods 1995-2009 and 1986-2009 respectively, was provided from the incidence database at the Cancer Registry of Norway.
Results: In the period 1995-97, 3.0 in 100,000 women with DCIS had breast conserving treatment (BCT), while 5.0 in 100,000 had mastectomy. In 2004-06 the rates were 8.6 and 4.2, respectively. In 1995-97, 18.7 in 100,000 women with breast cancer had BCT, while 77.3 in 100,000 had mastectomy. In 2004-06 the rates were 57.9 and 50.8, respectively. The percentage of women with DCIS or breast cancer who were treated with BCT was lower in 2007-09 in all counties than in 2004-06. For 2007-09 the percentage of women with DCIS who were treated with BCT varied by county from 39% to 75%. For breast cancer the percentage varied from 33% to 67%.
Interpretation: The number and percentage of women with DCIS or breast cancer who were treated with BCT increased until 2005, then it fell, and the percentage varied between counties. The reasons for this need to be identified and followed up with regard to the recommendations from the Norwegian Breast Cancer Group.