Accelerating Prostate Stereotactic Ablative Body Radiotherapy (SABR): Efficacy and Toxicity of a Randomized Phase II Study of 11 Versus 29 Days Overall Treatment Time (PATRIOT Study; ClinicalTrials.gov NCT01423474)

Prognostic significance of nadir PSA value and time to nadir PSA in patients with metastatic castration-naive prostate cancer receiving first-line hormonotherapy

BACKGROUND

The current study aimed to evaluate the effect of the time duration to reach the lowest prostate-specific antigen (PSA) from the onset of first-line hormonal treatment (time to nadir PSA, TTNpsa) on survival in castration-naive metastatic prostate cancer (CN-MPC) patients.

METHODS

Eighty patients who had PSA response >80% with first-line hormonal therapy (luteinizing hormone-releasing hormone, LH-RH analog +/- bicalutamide) were included in this study.

RESULTS

Under androgen deprivation therapy (ADT), a significant positive correlation was found between TTNpsa, nadir PSA (Npsa) duration, and progression-free survival (PFS) ( p < 0.001) and overall survival (OS) ( p < 0.001). There was no correlation between TTNpsa and Npsa duration. TTNpsa and Npsa durations were independently correlated with PFS and OS. In patients with TTNpsa value ≥19 weeks, the median PFS was 126 (95% CI, 68-184) weeks compared with TTNpsa <19-week group in which the median PFS was 44 (95% CI, 26-62) weeks ( p = 0.033). In patients with TTNpsa value ≥19 weeks, the median OS was 242 (95% CI, 169-315) weeks compared with TTNpsa <19-week group in which the OS was 156 (95% CI, 89-223) weeks ( p = 0.018). The median nadir PSA value was 1 ng/mL. The median PFS was significantly longer in the patient group with ≤1 ng/mL (137 weeks, 95% CI, 50-224) compared with the group with >1 ng/mL (41 weeks, 95% CI, 34-48) ( p < 0.001). The median OS was significantly longer in the patient group with nadir PSA ≤1 ng/mL (296 weeks, 95% CI, 220-272) compared to the group with >1 ng/mL (131 weeks, 95% CI, 84-178) ( p = 0.002). In patients with nadir PSA ≤1 ng/mL ( n = 40), there was no relationship between TTNpsa and Npsa duration with both PFS and OS. However, in patients with nadir PSA >1 ng/mL ( n = 40) subgroup, there was a significant positive correlation between TTNpsa and PFS, and OS ( p < 0.001, P = 0.016, respectively).

CONCLUSION

In CN-MPC who received first-line ADT, especially in the group with the nadir PSA value >1 ng/mL, the duration of TTNpsa was positively correlated with PFS and OS.

Stereotactic Ablative Body Radiotherapy for Intermediate- or High-Risk Prostate Cancer

Stereotactic ablative radiotherapy (SABR) is a relatively novel form of high precision radiotherapy. For low- and intermediate risk patients, ultrahypofractionation (UHF - more than 5 Gy per day) has been compared to conventionally fractionated or moderately hypofractionated radiotherapy in two large randomized studies. A third smaller randomized study examined the question of the optimal frequency of treatments. The results of these studies will be reviewed. SABR for high risk prostate cancer has been shown to be feasible and is well tolerated with careful planning and setup techniques. However, there is currently insufficient data supporting its use for high-risk patients to offer SABR outside of a clinical trial. SABR costs less to the radiotherapydepartments and, the patient, as well as increasing system capacity. Therefore, it has the potential to be widely adopted in the next few years.