More data on less fractions.
Top Line: While treating elective pelvic nodes in prostate radiation remains controversial, should their inclusion affect decisions of fractionation?
The Study: Currently, ASTRO does not include cases of treating pelvic nodes in its recommendation for prostate hypofractionation. This is curious because there’s actually quite a bit of data on the safety and efficacy of this approach when compared to conventional fractionation, if not on the efficacy of inclusion of nodes at all. But don’t take our word for it. Here is a meta-analysis of 18 prospective (n=14) and retrospective (n=4) studies comprising 1745 patients with high-risk prostate cancer receiving hypofractionated radiation at 2.2-3.4 Gy per fraction to the prostate with simultaneous conventional fractionation to the pelvic nodes (44-56 Gy over 22-28 fractions). Indeed, both disease control and safety were par for the course for pelvic radiation. Survival free from biochemical recurrence was 90% at 5 years and 78% at 10 years. At ten years, rates of local / pelvic recurrences were miniscule (0.38% / 0.13%), far outweighed by distant recurrence (7%) as expected—likely obviating any overarching benefit with adding treatment to the nodes in the first place, but that’s not the subject of discussion here. Rates of late grade 3+ GI and GU toxicity were roughly 1% each.
TBL: Neither efficacy nor safety is compromised when hypofractionating radiation to the prostate simultaneous with conventionally-fractionated pelvic nodal radiation. | Viani, Int J Radiat Oncol Biol Phys 2022