Comparison of PSA value at last follow-up of patients who underwent low-dose rate brachytherapy and intensity-modulated radiation therapy for prostate cancer

BACKGROUND: To compare the PSA value at the last follow-up of patients who underwent prostate low-dose rate brachytherapy (LDR-BT) with that of patients who underwent intensity-modulated radiation therapy (IMRT). METHODS: A total of 610 prostate cancer patients (cT1c-3bN0M0) were enrolled, and 445 of them underwent LDR-BT, while 165 received IMRT (74–76 Gy). The median follow-up period of these two groups was 75 months (LDR-BT) and 78 months (IMRT), respectively. We also evaluated the biochemical recurrence (BCR)-free rate using two definitions (Phoenix definition and PSA ≥ 0.2 ng/mL). RESULTS: The percentage of patients who achieved PSA < 0.2 ng/mL at the last follow-up was 77.5% in the LDR-BT group and 49.7% in the IMRT group (p < 0.001). Among patients with a normal testosterone level at the last follow-up, the percentage of those who achieved PSA < 0.2 ng/mL at the last follow-up was 79.2% in the LDR-BT group and 32.1% in the IMRT group (p < 0.001). The 5-year BCR-free rate by the Phoenix definition in the IMRT and LDR-BT groups was 89.5 and 95.0% (p < 0.001), respectively. On the other hand, the 5-year BCR-free rate using the definition of PSA ≥ 0.2 ng/mL was 59.1 and 80.1% in the IMRT and LDR-BT groups, respectively (p < 0.001). CONCLUSIONS: The PSA value at the last follow-up of LDR-BT was significantly lower than that of IMRT, and this result was particularly marked in patients with a normal testosterone level at the last follow-up.