Radiotherapy spares the things prostate surgery damages, and damages something surgery leaves alone

This publication has now reported three times on what happens to Korean men with prostate cancer, and each time the account has stopped at the same place. One article established that more than half of Korean cases are high-risk at diagnosis. One found that men left under surveillance started antidepressants more often than men who were treated. One identified what predicts incontinence after robotic prostatectomy, and closed by noting that radiotherapy has its own functional profile which appeared in none of the evidence cited.

That is a gap in our own coverage, and it matters because a man declining surgery is usually not choosing between surgery and nothing.

The randomised comparison#

The only trial that randomised men between monitoring, surgery and radiotherapy and then asked them how they were is ProtecT, which followed patient-reported urinary, bowel and sexual function in 1,643 British men for six years, with questionnaire completion above 85 percent for most measures.

The pattern is close to a straight exchange. Surgery takes continence and erections and leaves the bowel alone. Radiotherapy largely leaves continence alone, costs less sexual function in the long run, and takes something surgery does not touch.

What Korean series report#

Two recent Korean studies report toxicity after radiotherapy, and between them cover both settings in which it is given.

The first treated 249 men with localised prostate cancer using CyberKnife stereotactic body radiotherapy, comparing 35 Gy in five fractions against 36 Gy in four, with a median follow-up of 50 months.

Three-year biochemical recurrence-free survival was 96.5 percent in the five-fraction group and 96.8 percent in the four-fraction group after adjustment for baseline imbalances, with no significant difference in toxicity between the schedules. Four sessions instead of five is a material difference to a man travelling for treatment, and on these numbers it cost nothing.

The second compared radiotherapy given after prostatectomy, where it is used to salvage a rising PSA: 112 propensity-matched men, half receiving 66 Gy over six weeks and half 55 Gy over four. Grade 1 urgency was more common with the longer schedule at three months (30.4 against 14.3 percent) and had resolved by a year; grade 2 diarrhoea was likewise more common early (26.8 against 8.9 percent). Late toxicity at one and two years did not differ, and no grade 3 or worse late genitourinary toxicity occurred in either arm. Grade 3 rectal bleeding occurred in 3.6 percent of the six-week group and 1.8 percent of the four-week group, a difference well within chance at this size.

Why the Korean numbers look so much better than ProtecT's#

A reader comparing the two sections will notice that the Korean series report bowel problems in one or two percent of men while ProtecT describes bowel function as measurably worse across a whole randomised group. Both are honest. They are not measuring the same thing.

1. The Korean studies grade toxicity with CTCAE, a clinician-assigned scale recorded at scheduled visits. ProtecT used validated questionnaires completed by the men themselves. Where the two have been compared in cancer treatment generally, clinician grading records fewer and milder symptoms than patients report.
2. A threshold of grade 2 or worse excludes everything a clinician judged mild. ProtecT reported change on a continuous scale, where a shift too small to reach grade 2 still appears.
3. The Korean series are single-institution retrospective cohorts with no untreated comparison group, so nothing separates a symptom caused by treatment from one a man of that age would have had anyway. ProtecT had randomised comparison groups and pre-diagnosis baseline questionnaires.
4. Technique differs by a generation. ProtecT delivered conformal radiotherapy with hormones in men treated from 1999 onwards; the Korean series used stereotactic technique in the 2010s and 2020s. Some of the gap is very likely real improvement, and this evidence cannot say how much.

What is still missing#

1. No Korean series here reports patient-reported outcomes. The gap this article set out to close is closed on clinician-graded toxicity and remains open on function as men experience it.
2. The stereotactic series is 249 men at one institution with three years of oncological follow-up, which is short for prostate cancer.
3. The salvage study describes radiotherapy after prostatectomy, a different clinical situation from radiotherapy as first treatment, and its 112 matched patients cannot detect small differences.
4. None of this compares radiotherapy against surgery in Korean men. The only randomised comparison of the two remains ProtecT.
5. Hormone therapy is given alongside radiotherapy in many men and has functional effects of its own. ProtecT's radiotherapy group received it; the Korean stereotactic series does not separate its effect out.

The through-line of this publication's prostate coverage has been that Korean data records what was done to men and what it cost the insurance system, but not what happened to the men. This is the first entry in that coverage where Korean data reports a harm at all. It reports it in the clinician's vocabulary rather than the patient's, which is a smaller gap than the one before it, and still a gap.