A bothersome prostate: volume and flow explain only 13% of symptoms

Three different prevalences, constantly conflated

When you read that one man in two has an enlarged prostate, it matters which measure is meant. Three exist and they do not say the same thing.

An enlarged prostate is ordinary. Symptoms that genuinely bother are much less so. And the link between the two is weak: age, prostate volume and maximum flow together explain only 13% of the variation in symptoms.

The figure of 80% to 90% enlargement after 80, attributed everywhere to Berry’s study, does not appear in its abstract. It comes from extrapolating a curve. We do not repeat it.

What becomes of a man who is not treated

It is the question nobody asks, and it has numerical answers.

Barry (J Urol, 1997) followed 500 men considered candidates for prostatectomy for four years, treated without surgery.

In the placebo arm of MTOPS, 737 men followed for four and a half years, overall clinical progression reaches 17%. But the detail, read in the 2010 American guideline, changes everything: 3.6 of the 4.5 events per 100 person-years were a four-point rise in the symptom score, which is 80% of the total. Invasive treatment involved 40 men, or 5.4%. And maximum flow in the placebo arm improved by 1.4 mL/s on average during the trial.

The 2026 European guidelines record that 79% of patients are clinically stable at five years under watchful waiting, and that about 85% of men with mild symptoms are stable at one year.

In the only randomised trial comparing surgery with watchful waiting (NEJM, 1995), 556 men with moderate symptoms, surgery halves the risk of treatment failure, relative risk 0.48 with an interval from 0.30 to 0.77. Twenty-four per cent of the watchful waiting group were operated on within three years. And the authors note that surgery was associated with neither impotence nor urinary incontinence.

The drugs, and the figure that puts them in proportion

The largest network meta-analysis (Yuan, Medicine, 2015), 124 trials and 58,548 participants, measures the effect of treatments beyond placebo.

Almost every drug effect falls below or at the edge of the clinical relevance threshold. That does not mean they are useless, it means the order of magnitude is modest and worth knowing before starting a lifelong treatment.

The other half of the story is the size of the placebo effect itself. In the L.I.F.T. trial, a sham cystoscopy produced 5.9 points of improvement out of the 11.1 obtained by the real procedure, which is 53% of the total effect. In the sham-controlled embolisation trial, the sham arm gains 5.03 points, more than any drug achieves beyond placebo. The American guideline states that placebo produces no more than one to two points of average improvement over four years.

Finasteride has one useful peculiarity: its effect depends on prostate size. The meta-analysis by Boyle (Urology, 1996) finds 1.8 points of improvement below 20 cc and 2.8 points above 60 cc, and the gap against placebo only becomes significant above 40 cc. The authors conclude that men with small prostates may not be suitable candidates.

Surgery, what it delivers and what it costs

Transurethral resection remains the benchmark everything else is measured against. The 2026 European guidelines, from a meta-analysis of twenty randomised trials, report a 162% improvement in maximum flow, a 70% reduction in symptom score and a 77% reduction in post-void residual, with durability confirmed by follow-up from eight to twenty-two years.

The complications come from a prospective Bavarian series of 10,654 patients (Reich, J Urol, 2008), in mostly non-university departments.

What men fear most is not what happens. Erectile function does not change significantly after resection. Retrograde ejaculation, on the other hand, is very common, with a relative risk of 13.31 in the meta-analysis by Manfredi (Eur Urol Focus, 2022) across 20,531 patients. The often quoted 65% to 75% has no primary source; randomised trials give 36% to 41% anejaculation.

On reoperation, the two large Austrian national cohorts stop at eight years: 7.4% then 8.3% repeat resection, 12.7% to 14.7% for any endourological reintervention. Any figure quoted at ten years is an extrapolation, and we do not present it as a measurement.

The newer techniques, and what the trials actually show

This is where the gap between the commercial promise and the published data is widest.

The urethral lift. The sham-controlled trial randomised over three months only; everything after that is an uncontrolled open series. At five years, surgical retreatment reaches 13.6%. The Cochrane review concludes the device appears less effective than resection on symptoms and flow, in the short and the long term. Efficacy on large median lobes has not been demonstrated.

Prostatic artery embolisation. The only randomised trial designed to test its non-inferiority (Abt, BMJ, 2018) did not demonstrate it.

The British UK-ROPE registry, 305 patients, finds the same: 10 points of improvement against 15 for resection, and no evidence of non-inferiority after matching. Reoperation after embolisation reaches 20% there. The Swiss trial authors write that further comparative results with longer follow-up should be assessed before embolisation can be considered a routine treatment.

Embolisation has one real, measured advantage: half as many adverse events, and 71% of procedures as day cases against 80% of resections needing at least one night. That is a trade-off between efficacy and burden, not an equivalence.

What the studies do not allow us to claim

The incidence of kidney failure caused by benign prostatic obstruction has no primary source. It appears as a component of a composite endpoint in the major trials, never reported separately. Alarming formulations of the kind that some percentage of untreated men develop kidney failure have no published denominator.

Persistent sexual dysfunction after stopping a 5-alpha-reductase inhibitor is described in case series and pharmacovigilance databases, with no controlled study and no denominator. The most recent systematic review concludes that effects were most often transient, while calling for standardised definitions of persistence, which amounts to saying the question is not settled.

In practice, if this concerns you

Three questions structure the discussion. What is your symptom score and above all how much does it actually bother you, since prostate volume says little. Has the proposed treatment been compared against a sham procedure or only against nothing, since the placebo effect accounts for half the result in this field. And if a newer technique is proposed, on which trial and over what horizon, since several were randomised for three months only.

Noria Health arranges a full urological work-up near Brussels within 24 to 48 hours: symptom score, flow measurement, post-void residual, prostate and bladder ultrasound, PSA and renal function. The report is issued within 24 hours, follow-up is structured at D14, D30 and D90, and surgery is considered only around day 10 if it is needed.

What Noria Health does not do: propose a procedure on prostate volume alone. Acute urinary retention, heavy blood in the urine, or fever with loin pain are matters for the emergency services in your country, immediately, not for an appointment.

Further reading

• Prostate: 3.1% mortality at 15 years under monitoring
• PSA and MRI, what 23 years of follow-up taught us
• Kidney stones, recurrence and the kidney

Sources

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20. European Association of Urology. Guidelines on the management of non-neurogenic male lower urinary tract symptoms, 2026. https://uroweb.org/guidelines/

See also: all our articles on urology.

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