How likely is late radiation induced lumbosacral plexopathy from treatment of anal cancer with chemo-RT 20 years ago and how would you manage it?   

It's difficult to say "how likely" since we don't really have good long-term reporting for this specific late complication. I would say it's rare, but certainly possible. Late lumbosacral plexopathy has been reported as far out as 36 years from pelvic RT (Krkoska et al., PMID 36510189).In general, t...