Breast cancer incidence and time trend in France from 1990 to 2007: a population-based study from two French cancer registries

Background: The hypothesis of a link between breast cancer and hormone replacement therapy (HRT) is evoked to explain the recent decrease of incidence observed in several countries. The purpose of our study is to analyse the evolution of breast cancer incidence by stage. Materials and methods: We used data from Tarn and Isere French cancer registries for the period 1990-2007. Trends of annual world population standardised incidence rates were studied using the Joinpoint method. Results: From 1990 to 1999, the incidence of invasive breast cancer increased annually by 1.2%, then by 4.8% from 1999 till 2003 and then decreased by 1.7%. For the women aged 50-74 years, annual changes were, respectively, 1.5%, 6.0% and 3.4%. In this group, the incidence of T1/T2-N0-M0 stages increased annually by 4.6% until 2003 and then decreased by 2.2%. Since 1990, the incidence of in situ breast cancer increased annually by 5%. From 2003 to 2004, prescribing of HRT decreased substantially. Conclusions: Since 2003, the incidence of invasive breast cancer decreased for women aged 50-74 years, mainly involving T1/T2-N0-M0 stages. The reduction in HRT prescription may partly explain this decrease. The incidence of in situ breast cancer didn't decrease during the whole period.