Survival of women with breast cancer in central and northern Denmark, 1998–2009

OBJECTIVE Breast cancer is the most common cancer among women worldwide. The Nordic countries have relatively high survival, but Denmark has a lower survival than neighboring countries. A breast cancer screening program was introduced in 2007 and 2008 in the northern and central regions of Denmark respectively. We aimed to examine possible changes in survival of Danish breast cancer patients in central and northern Denmark in the period 1998-2009. MATERIALS AND METHODS From the northern and central Denmark regions, we included all women (n = 13,756) with an incident diagnosis of breast cancer, as recorded in the Danish National Registry of Patients during the period January 1, 1998 through December 31, 2009. We calculated age-stratified survival and used Cox proportional hazard regression to estimate mortality rate ratios (MRRs) for all breast cancer patients. RESULTS Median age was 62 years (21-102 years). The overall 1-year survival improved steadily over the period from 90.9% in 1998-2000 to 94.4% in 2007-2009, corresponding to a 1-year age adjusted MRR of 0.68 in 2007-2009 compared with the reference period 1998-2000. We estimated the 5-year survival to improve from 70.0% in 1998-2000 to 74.7% in 2007-2009, corresponding to a 5-year age adjusted MRR of 0.82 in 2007-2009 compared with the reference period 1998-2000. For middle-aged women (50-74 years) 1-year survival increased from 92.8% in 1998-2000 to 96.6% in 2008-2009, and 5-year survival was expected to increase from 73.9% in 1998-2000 to 80.2% in 2007-2009. Among younger women (15-49 years) and elderly women (>75 years), 1-year survival and 5-year predicted survival did not change over the two time periods. CONCLUSION Survival of breast cancer patients has improved in Denmark over the period 1998-2009, and this change was most distinct in women aged 50-74 years. Survival improved even before the implementation of a formal breast cancer screening program.