Top Line: Is there a benefit for elective nodal radiation for men with high-risk prostate cancer?
The Study: There have been two main trials that asked whether we should treat pelvic nodes for intact prostate cancer. GETUG-01, in patients of various risk level, suggested a numeric (but not significant) improvement in 10-year event-free survival (62.5→ 77.2%). RTOG 9413, well, you know the story. Here’s data from the modern, randomized POP-RT trial from Tata Memorial Centre. In it, 224 men with GS 8+, GS 7 and PSA > 15, GS 6 and PSA > 30, or T3b+ disease were randomized to prostate RT with or without pelvic nodal RT. Two notable differences here compared to older trials are the focus on high and very-high risk disease and the use of advanced imaging (80% had PSMA-PET) for accurate staging. The primary target was the prostate with a 7 mm (5mm posterior) margin, which was prescribed 68 Gy in 25 fractions. The nodal volume was prescribed 50 Gy in the same 25 fractions. The protocol contains details about dose constraints. Two years of ADT was administered starting at least 8 weeks prior to radiation. The study was designed to show a 17% improvement in biochemical failure-free survival (bFFS) at 5 years. Only 36 of a planned 120 biochemical failure events actually happened. Even so, 7 of those occurred in the WPRT arm compared to 29 in the PORT arm. Over half (52%) of recurrences in the PORT arm were in the pelvis compared to just 12.5% with WPRT. That resulted in a significant improvement in 5-year bFFS from 82→ 95%. Pelvic RT also improved 5-year DFS from 77.2→ 89.5%. A post hoc analysis showed an improvement in DMFS with pelvic RT. There was no difference in OS.
TBL: In men with high and very-high risk prostate cancer receiving long-term ADT, adding pelvic nodal coverage to moderately hypofractionated prostate radiation improves bFFS and DFS at 5 years. | Murthy, J Clin Oncol 2021