Intensifying Salvage Treatment Reduces Risk of Prostate Cancer Progression

Intensification of salvage treatment can reduce the risk of prostate cancer progression after prostatectomy, according to research published in The Lancet.

Researchers found that adding short-term androgen deprivation therapy (ADT) to prostate bed radiotherapy (PBRT) could reduce the risk of progression. The risk was further reduced by adding both short-term ADT and pelvic lymph node radiotherapy (PLNRT) to PBRT.

The phase 3 SPPORT trial (ClinicalTrials.gov Identifier NCT00567580) enrolled 1792 patients with prostate cancer who had detectable prostate-specific antigen after prostatectomy. 

The patients were randomly assigned to receive PBRT alone (n=592), PBRT plus 4 to 6 months of ADT (n=602), and PBRT plus PLNRT and 4 to 6 months of ADT (n=598). Baseline demographics and clinical characteristics were well balanced across the 3 treatment groups. 

The study’s primary endpoint was freedom from disease progression (defined as biochemical failure by Phoenix criteria, clinical failure, or death from any cause) at 5 years after treatment.

The final analysis was conducted at a median follow-up of 8.2 years, and 1716 patients were evaluable. The 5-year rate of freedom from progression was 70.9% in the PBRT-alone group, 81.3% in the ADT-PBRT group, and 87.4% in the PLNRT-ADT-PBRT group. 

When compared with the PBRT-alone group, the 5-year rate of freedom from progression was significantly higher in the PLNRT-ADT-PBRT group (16.5% difference, P <.0001) and in the ADT-PBRT group (10.4% difference, P <.0001).

The difference between the ADT-PBRT group and the PLNRT-ADT-PBRT group did not reach the prespecified threshold for statistical significance (6.1% difference; P =.0027).

Acute grade 2 or higher adverse events occurred in 44% of patients in the PLNRT-ADT-PBRT group, 36% in the ADT-PBRT group, and 18% in the PBRT-alone group (P <.0001). Grade 3 or higher adverse events occurred in 11%, 7%, and 3% of patients, respectively (P <.0001). 

Overall, there were no significant between-group differences in grade 2 or higher late toxicities or grade 3 or higher late toxicities.

“The results of this randomized trial establish the benefit of adding short-term ADT to PBRT to prevent progression in prostate cancer,” the researchers wrote. “To our knowledge, these are the first such findings to show that extending salvage radiotherapy to treat the pelvic lymph nodes when combined with short-term ADT results in meaningful reductions in progression after prostatectomy in patients with prostate cancer.”

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Pollack A, Karrison TG, Balogh AG, et al. The addition of androgen deprivation therapy and pelvic lymph node treatment to prostate bed salvage radiotherapy (NRG oncology/ RTOG 0534 SPPORT): An international, multicentre, randomized phase 3 trial. Lancet. 2022;399(10338):1886-1901. doi:10.1016/S0140-6736(21)01790-6