Adding ADT to RT Improved PFS After Radical Prostatectomy

June 4, 2015

Assigning prostate cancer patients in relapse after prostatectomy to ADT and radiation therapy delayed disease progression compared to radiation therapy alone.

Assigning men in biological relapse after radical prostatectomy to combined salvage treatment with hormone therapy and radiation therapy significantly delayed disease progression compared with radiation therapy alone, according to the results of the GETUG-AFU 16 phase III trial (abstract 5006).

“Salvage radiotherapy combined with limited androgen deprivation therapy improves the 5-year progression-free survival rate compared to radiotherapy alone,” said study presenter Christian Carrie, MD, of the department of radiation oncology at the University of Lyon-Centre Leon Berard. “There is no significant difference in overall survival, but the follow-up is still too short.”

Between October 2006 and March 2010, 743 patients were enrolled in GETUG-AFU 16 and randomly assigned to radiation therapy alone (n = 374) or radiation plus hormone therapy with goserelin 10.8 mg for 6 months (n = 369). The primary endpoint of the trial was progression-free survival.

Patients were followed for a median of 63.1 months, during which there were 138 cases of disease progression in the radiation alone arm and 78 in the combined arm. Assignment to combined salvage therapy resulted in a significantly improved 5-year progression-free survival of 79.6% compared with 62.1% with radiation therapy alone (hazard ratio [HR] = 0.50; 95% CI, 0.38–0.66; P < .0001).

“This benefit was the same for all the subgroups analyzed including by risk group, technique of radiation therapy, the PSA at time of randomization, or PSA doubling time,” Carrie said.

No significant difference in 5-year overall survival was seen (96.2% for combined therapy vs 94.8% for radiation therapy).

Eleven patients died of progressive disease: eight in the radiotherapy alone arm and three in the combined arm.

No difference in grade 3 acute toxicities or late toxicities were found between the two arms, but there was significantly more grade 2 hot flush or sweats in patients assigned to hormone therapy (P < .001).

Commenting on the results of this study, Celestia S. Higano, MD, FACP, of the University of Washington called the progression-free survival results “very encouraging.” However, given the very small number of deaths that occurred, she said many more years of follow-up will be required to define prostate-cancer specific survival and overall survival.