When we modeled co‐expression of both markers, the negative prostate cancer risk association with NF‐κB expression remained (OR =0.87; 95% confidence interval [CI] =0.77–0.99; p = 0.03) and there was also a nominal positive association between case status and GDF‐15 expression (Table 2). This evidence concerns the gene NFKB1 and Familial prostate cancer.