In the only randomized comparative study I'm aware of, they're both about
equal on that dimension in the long term.
Grills et al. said...High dose rate brachytherapy as prostate cancer monotherapy reduces toxicity compared to low dose rate palladium seeds.
Biochemical control was 97% and 98% for LDR and HDR, respectively.
HDR brachytherapy alone was associated with decreased acute rates of:
• grade 1 to 3 dysuria (67% versus 36%)
• urinary frequency/urgency (92% versus 54%), and
• rectal pain (20% versus 6%).
Selected chronic toxicities were also decreased with HDR, including long-term:
• urinary frequency and urgency, 32% (HDR) vs 56% (103Pd)
There were no differences in the rates of:
• chronic dysuria
• urinary incontinence
• retention or
Urethral stricture rates were 8% in the HDR alone group vs 3% for 103 Pd (not statistically different).
The 3-year actuarial impotence rate was 45% for the LDR group and only 16% for HDR.
In the short term
, UW Seattle, arguably the best, reported 43% acute urinary retention in 2002
-- I don't know if they've improved on that or not since then. Washington U reported a similar rate - 34%
. HDR (Demanes] reported 13% Grade 2 & 3 urinary retention (10% & 3% respectively). FYI, Katz using SBRT reported no urinary retention requiring treatment (acute or late, with only 4% Grade 2 urinary SEs).