What is your radiotherapy fractionation recommendation for favorable intermediate risk prostate cancer who has ~70 cc prostate?

This may seem controversial in 2026 and seems to contradict evidence, but I just wanted to relay what I've seen.

I was a fairly early adopter of moderate hypo-fractionation, not the first, but not the last - probably around 2012-2013. I pretty much changed to that for all patients for around 11-12 years. 70 in 28 for everyone. Some modifications, if needed, for SV and/or pelvic LNs, but the total fx was constant at 28.

I joined a new practice a little over a year ago. Due to the nature of our practice, I cover many of my colleagues' weekly management visits. It was becoming quite clear to me that my patients treated with 70 Gy in 28 fractions definitely had more urinary side effects than those being treated with 1.8 Gy. Nothing earth-shatte...

For a patient with intermediate-risk prostate cancer and a 73 cc gland, I would offer any validated EBRT fractionation schedule so long as the burden of LUTS was manageable. In my practice, this includes a 28-fraction, 20-fraction, and 5-fraction regimen off study, although there are multiple fractionation schedules in conventional fractionation that are validated to have clinically comparable efficacy.

Although it is not reliably seen in all studies, SBRT (5-fraction) schedules tend to have a higher impact on GU toxicity (Tree et al., PMID 36113498). Much of the initial work on prostate SBRT used similar eligibility criteria as those for brachytherapy, which are in part based on gland volume and lower urinary tract symptoms (LUTS). This ex...

Dr. @Dr. First Last has a nice review of some of the literature, and in general, I think this is an area that will probably remain debated for some time, as multiple drivers of urinary events and developing biomarkers.

Another paper I like is the Urinary Tract Events after Prostate RT, which uses a big Swedish registry to identify admissions or specialist visits related to LUTS, infections/UTI's, or urologic procedures (e.g., TURP for obstruction or blood clot extraction for cystitis).

Notably, higher pre-Tx IPSS and gland size correlated with more urinary issues but didn't vary much by RT schedule (admittedly, this was not randomized/controlled systematically). Of all comers, 3yr incidence of urinary event was 28% after conventional, 27% a...

I believe there are some excellent responses noted, but I wanted to add one more element. I agree that the conventional fractionation does have less acute urinary side effects than the hypofractionated or SBRT approach, but the increased burden of treatments probably makes it not worth it for a majority of patients. I have also found that the size of the gland correlates with increased urinary side effects, but it does not mean that individuals will have increased side effects. Side effects probably better correlate with current urinary issues (IPSS). That is somewhat debatable. What I wanted to add is the availability of radiogenomic assays.

These are genetic assessments of the patient's normal tissue (usually a cheek swab) that look for g...

I have the same hot take as Simul - 79.2 Gy in 1.8 Gy per fraction. If you look at the supplementary data in PACE-B, you can see that late adverse effects were about 10% worse with SBRT. Although technically meeting noninferiority, adverse effects are in the direction of SBRT. If you look at the adverse effects in RTOG 0415, there is the same trend.

We also know from PACE-B that acute adverse effects are a surrogate for late adverse effects. Nocturia is also not so benign: there is evidence that nocturia increases mortality (Pesonen et al., PMID 31347956). There seem to be hints of this also in the adjuvant vs salvage data: in TROG RAVES and GETUG-AFU 17, overall survival appears worse in the direction of adjuvant. Sleep is one of the most i...

For big prostates and corresponding AUA scores, I migrate from hypo to standard fx. The cutoff is not hard and fast, but 75 cc and above, it's due for consideration.

Having feelings about using IPSSs to determine long-term GU effects of RT remains a little hazy to me. Last time I studied this in depth, I found a (mostly) inverse correlation between pre-treatment and post-treatment IPSSs (using 81 Gy/45). The linear regression equation was

change in IPSS = 6.2 - 0.8∗(pre-tx IPSS)

Implying that if you had an IPSS of about 8 or greater, you could see a decrease in IPSS w/XRT; men with IPSSs in the ~23 and up range saw median ~16-point decreases (!).

This correlation has been seen pretty routinely in fact (e.g., Malik et al., PMID 20643513 and Gorovetes et al., PMID 33665486) regardless of fraction sizes, although the net IPSS decreases may be a little less w/ hypofx... however, may need to brib...