Pretreatment PSA levels affects the completion rate of Ra-223 treatment.

The aim of this study was to review our initial experience of using radium 223 (Ra-223) for metastatic castration-resistant prostate cancer (CRPC) and to evaluate whether pretreatment PSA levels correlate with completion of Ra-223 treatment. In addition, we examined change ratios of PSA, ALP and BAP after the third administration to evaluate the correlation of these change ratios with completion of the subsequent Ra-223 treatment. Forty patients were enrolled in this retrospective study. Ra-223 treatment was considered completed in patients who received five or six administrations. Patient backgrounds and changes in biomarkers were compared between patient groups (complete vs. incomplete Ra-223 treatment). PSA levels before treatment were significantly lower in the complete compared with the incomplete group (cutoff value; 21.7). ALP and BAP levels had decreased after the third administration in the complete group, compared with baseline levels, while levels in the incomplete group had increased. Significant difference was seen in ALP levels, while was not seen in BAP levels between the two groups. Ra-223 treatment should be considered for CRPC with low PSA levels. Changes in PSA and ALP during Ra-223 treatment might provide markers to identify patients likely to complete Ra-223 treatment, with implications for prognosis.