GDF15 and prostate cancer: Clearly, a high degree of variation in GDF‐15 expression exists in the different stages of prostate cancer,21 and studies of prostate cancer field cancerization 35, 36 suggest that GDF‐15 may be overexpressed in tumor‐adjacent normal glands, and this might explain the association we found between GDF‐15 expression and elevated prostate cancer risk in AA men.