Assess Gamma H2AX Positivity in Circulating Prostate Cancer Cells Before and After Radium 223

Blood collection for baseline CTC numeration and H2AX assay. Circulating prostate cancer cell analysis requires blood draw of 7.5 ml (about 1 ½ teaspoons) of blood, to be performed at the screening, 1-2 hours before the third and sixth dose of radium 223 and 24 hours after the first, third, sixth dose of Radium 223. Standard of care Radium 223 treatment is given every 4 weeks for a total of 6 treatments and post Radium 223 follow up at week 24 is also considered standard of care. Other than these standard clinic visits and treatments, the study only requires 3 extra trips to the cancer center for blood draw at 24 hours after the first, third, sixth dose of Radium 223. Blood draws other than circulating tumor cell analysis is considered standard of care and doesn't require extra visits.