That's discussed in the following:
Combining ADT and salvage radiation therapy improves outcomesThe detail of GETUG-AFU 16 that would break down results by Gleason score has not yet been published. We don't yet have the results of other clinical trials that would tell us the optimal timing for various recurrent risk groups (RTOG0534 and RADICALS).
To some extent, use of ADT is probably substitutable for radiation dose. More important is the dose of radiation used. It is not always immediately obvious. The
nominal dose, expressed in Gray (Gy), is different from the Biologically Effective Dose (BED, also expressed in Gy), and depends on the treatment schedule. For example, all of the following salvage doses to the prostate bed are biologically equivalent in their cancer control power (treatments are called "fractions.") even though the
nominal dose ranges from 81 Gy to 44 Gy.:
54 fractions of 1.5 Gy/fraction
=41 fractions of 1.8 Gy/fraction
=35 fractions of 2.0 Gy/fraction
=25 fractions of 2.5 Gy/fraction
=18 fractions of 3.0 Gy/fraction
=11 fractions of 4.0 Gy/fraction
The standard of care is 35-41 fractions of 1.8- 2.0 Gy, although ROs have used the other treatment schedules experimentally. Someone in my support group recently completed his salvage radiation under a clinical trial at USC in 15 fractions and has so far had no side effects of treatment. As I said, the standard of care for the pelvic LNs is around 25 fractions of 2.0 Gy, although that is much less proven.
- Allen