DNA methylation markers for risk of metastasis in a cohort of men with localized prostate cancer

Accurately identifying life-threatening prostate cancer (PCa) at time of diagnosis remains an unsolved problem. We evaluated whether DNA methylation status of selected candidate genes can predict the risk of metastasis beyond clinical risk factors in men with untreated PCa. A nested case-control study was conducted among men diagnosed with localized PCa at Kaiser Permanente California between 01/01/1997-12/31/2006 who did not receive curative treatments. Cases were those who developed metastasis within 10 years from diagnosis. Controls were selected using density sampling. Ninety-eight candidate genes were selected from functional categories of cell cycle control, metastasis/tumour suppressors, cell signalling, cell adhesion/motility/invasion, angiogenesis, and immune function, and 41 from pluripotency genes. Cancer DNA from diagnostic biopsy blocks were extracted and analysed. Associations of methylation status were assessed using CpG site level and principal components-based analysis in conditional logistic regressions. In 215 cases and 404 controls, 27 candidate genes were found to be statistically significant in at least one of the two analytical approaches. The agreement between the methods was 25.9% (7 candidate genes, including 2 pluripotency markers). The DNA methylation status of several candidate genes was significantly associated with risk of metastasis in untreated localized PCa patients. These findings may inform future risk prediction models for PCa metastasis beyond clinical characteristics.