Breast density and residual by time of diagnosis since enrolment. a and c Histograms and empirical cumulative distribution functions for breast density. b and d Histograms and empirical cumulative distribution functions for age, body mass index and type of image adjusted residual. The cancers are split into those diagnosed within 100 days of entry (<100-d) and more than 100 days (100-d+). A Wilcoxon test for the difference between <100 days and 100+ days yielded P = 0.34 for visual analogue scale (VAS) and P = 0.98 for the residual.