Trends in molecular subtypes of breast cancer: description of incidence rates between 2007 and 2012 from three French registries

Background The incidence and incidence trends of breast cancer according to molecular subtype are unknown at a population level in France. The registry data enables this study and may give this information, that is crucial to describe and understand breast cancer epidemiology. Methods We estimated the incidence rates of breast cancer for each molecular subtype using data from three cancer registries in France for the period from 2007 to 2012. Molecular subtypes were defined with immunohistochemical data. Poisson models were estimated to modelize the course of breast cancer incidence and to test the trends. Results The study included 12,040 patients diagnosed between 2007 and 2012 in the three administrative areas covered by the registries. There was no significant trends in the proportion of each molecular subtype year by year. The age distribution of incident cases was different depending on the molecular subtypes (p