The fossa ‘bout dose.

Top Line: Does dose escalation improve biochemical control for post-prostatectomy salvage radiation?

The Study: The ideal dose for post-prostatectomy radiation is uncertain. And while many people fall in the 64.8-68.4 Gy range, some believe that dose escalation to 70+ Gy could improve disease control outcomes. A small randomized trial showed no overall improvement in biochemical control with 72 Gy vs 66 Gy, although there was a suggestion of benefit in men with high grade disease. The SAKK 09/10 trial was recently presented in abstract form at ASCO GU. Men (n=350) with rising PSA > 0.1 (after a nadir ≤0.4) no higher than 2 (median 0.3) were enrolled to receive radiation to the prostate fossa without ADT. The question was whether dose escalation would reduce the rate of biochemical progression, which was defined as a post-RT PSA ≥ 0.4 and rising. Patients were randomized to either 64 Gy / 32 or 70 Gy / 35 to the prostate fossa without nodal irradiation or ADT. At 6 years, the rate of freedom from biochemical progression was also similar with standard vs escalated dose (62% vs 61%). Neither was there a significant difference in the median time to biochemical progression between standard dose (8.2 years) and the escalated dose (7.6 years). Toxicity was fairly similar with the exception of a significant increase in late grade 2+ GI toxicity (7→ 20%) with escalation. There was also no difference in survival outcomes and no difference in the time to ADT initiation. Lastly, no specific subgroups seemed to derive benefit from dose escalation.

TBL: Dose escalation from 64 → 70 Gy does not improve biochemical control or survival outcomes for men receiving salvage radiation to the prostate fossa. | Ghadjar, ASCO GU 2021