Fig. 1.

Study design. (a) Distribution of samples over time and individual age at time of sampling. Blue dots correspond to samples from the Västerbotten Intervention Program (VIP) and red dots to samples from the Mammography Screening Program (MA). (b) The VIP-study has been collecting samples since 1985 and the vast majority of the individuals in this study have donated samples at multiple occasions, some over a period of over 3 decades. (c) With the exception of July, the samples have been collected throughout the whole year.