While not common in injury research, Bayesian changepoint methods have been applied to such public health questions as declines in violent assault following closings of alcohol outlets (Yu et al. [2008]), evaluating the clinical significance of serial CD4 counts (Ghosh and Vaida [2007]), and biomarker assays (Bellera et al. [2008]), and predicting cancer recurrence (Pauler and Finkelstein [2002]). This evidence concerns the gene CD4 and cancer.