Background: Diagnostic and treatment of breast cancer has steadily improved in the last decades; mammography-screening, more aggressive axillary surgery and finally sentinel lymph node biopsies. This study analyses the impact of time trends in diagnostic and surgical procedures on stage at diagnosis and survival in three Danish counties in three decades.
Methods: We compare extent of disease and outcome in three complete population-based patient cohorts with primary invasive breast cancer, diagnosed in 1986, 1996-1997 and 2002-2003; 3 385 patients, thereby comparing populations with and without centralised breast cancer management, mammography-screening, sentinel lymph node biopsies and the effect of time-period.
Results: The 5-year over-all survival increased significantly (p <0.001) from 74% (70-78) in 1986 to 84% (82-86) in 2002-2003 with a corresponding increase in 10-year relative survival from 63% (58-68) in 1986 to 74% (71-77) in 1996-1997. In 1986 patients from Funen had median 10 lymph-nodes removed vs. median 5 and 7 in the other counties (p <0.001), and significantly more patients had positive lymph-nodes. In 1996-1997 the number of lymph-nodes removed increased significantly in all counties (median 12,13,14). In Funen, mammography-screening was implemented and patients had more favourable stage distribution (p <0.001). This was associated with significantly better over-all survival in univariate- but not in multivariate analysis. In 2002-2003 we found smaller tumors and more favourable stage-distribution in patients from Funen (p <0.001), and the 5-year relative survival increased to 90% (86-93). With increasing attention to the axilla more patients were found with positive nodal status, least in Funen (45% vs. 51% and 53%) (p <0.001). We found no significant differences in over-all survival according to county.
Conclusion: During these three decades over-all survival of breast cancer improved. In the earlier periods we found survival differences according to residence, but in the late cohort there were no difference despite better stage distribution in the county with mammography-screening.