Adherence to changing guidelines among real-world early breast cancer patient in Finland over two decades

Abstract Purpose : The incidence of breast cancer has increased and many of them are detected with favorable tumor characteristics and alongside the aging of the population in older age. At the same time, the adjuvant treatment recommendations have been extended to cover even more patient sub-groups. This raises the question of how closely the guidelines can and will be followed in daily practice. Methods : Data from 803 primary early breast cancer patients in one university hospital district in Finland during two decades from 1992 to 2011 was retrieved from the Finnish Cancer Registry and combined with data from the Mass Screening Registry. The implementation of new systemic treatment and the adherence to the existing national guidelines was analyzed using multivariate logistic models. Results : The proportion of patients treated with adjuvant chemotherapy increased from 19.3% to 52.2% and with adjuvant endocrine therapy from 26.6% to 74.5%. Also, the proportion of patients with a guideline-based indication for systemic adjuvant treatment increased from 43.8% to 98.9% but the adherence to guidelines decreased from 88.2% to 70.1% in the most recent years of the study. Conclusions : New systemic treatments of early breast cancer were promptly adopted to clinical practice at the beginning of the 21 st century. However, at the same time adherence to the existing guidelines decreased significantly. The risk of undertreatment was especially high among elderly patients. As the treatment indications expand, more patient related individual consideration will be exercised in treatment decisions increasing the probability of undertreatment with respect to the guidelines.