Do you ever dose escalate radiotherapy to the primary in low volume metastatic prostate cancer?

Background: STAMPEDE Arm H (SOC ± RT to prostate) allowed for two fractionation schedules, 55 Gy in 20 daily fractions (67 Gy EQD2[α/β = 1.5]) and 36 Gy in 6 weekly fractions (77 Gy EQD2[α/β = 1.5]), without correction for treatment duration), and approximately half of participants received each schedule. At 5 years, the OS was similar within the low-volume subgroup between those who received either the daily or weekly dose schedule and the grade 3+ toxicity profile of both were similar.

Efficac...

Dr. @Dr. First Last gives an excellent and thorough answer. The only other thing I would add for comparison is the CHHiP trial itself and looking at the 57 Gy in 19 Fx vs 60 Gy in 20 Fx arms for comparisons of efficacy and toxicity.

5-year bPFS was 91% in the 60 Gy and 86% in the 57 Gy arms with a HR of 0.70 (95% CI 0.55-0.88, p=0.0026). When looking at the high-risk subgroups, 5-year bPFS was 84% in the 60 Gy and 78% in the 57 Gy suggesting again that ~5% benefit from that 'full' dose. Notably, ...