UNBLOCS: Thulium Laser Vaporesection versus TURP for Benign Prostatic Obstruction

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In 410 UK men with benign prostatic obstruction randomized under anesthesia, thulium laser vaporesection (ThuVARP) and TURP were equivalent for IPSS at 12 months, but TURP gave a higher Qmax; hospital stay and complication rates were similar.

IPSS was equivalent, but TURP gave a higher Qmax; ThuVARP did not shorten stay or reduce complications.

UNBLOCS was a pragmatic, patient-blinded, parallel-group equivalence randomized trial of thulium laser transurethral vaporesection of the prostate (ThuVARP) versus transurethral resection of the prostate (TURP) in 410 men at seven UK hospitals with bothersome lower urinary tract symptoms (LUTS) or urinary retention from benign prostatic obstruction, with the International Prostate Symptom Score (IPSS) and maximum urinary flow rate (Qmax) at 12 months as co-primary endpoints. IPSS was equivalent (adjusted difference 0.28 points, 95% CI -0.92 to 1.49), whereas Qmax was 3.12 mL/s lower after ThuVARP (95% CI -5.79 to -0.45), outside the equivalence margin.^[1]

Design and population

Pragmatic, patient-blinded, parallel-group equivalence randomized trial. 410 men at seven UK hospitals with bothersome lower urinary tract symptoms or urinary retention from benign prostatic obstruction who were suitable for TURP; 52% were catheterized at baseline and prostate size was not restricted.

Arms

Thulium laser transurethral vaporesection of the prostate (ThuVARP) versus transurethral resection of the prostate (TURP)

Report and follow-up

2020 · 12 months after surgery; follow-up completed December 2017

Endpoint	Results	Effect	Finding
Mean IPSS at 12 months (ThuVARP minus TURP, adjusted for centre and baseline diagnosis)	6.43 vs 6.26	difference 0.28; CI -0.92–1.49	Met
Mean Qmax at 12 months in mL/s (ThuVARP minus TURP, adjusted for centre and baseline diagnosis)	20.16 mL/s vs 23.24 mL/s	difference -3.12; CI -5.79–-0.45	Not met

Harms: At least one postoperative complication: 96/203 (47%) vs 91/204 (45%); Blood transfusion: 3/200 (2%) vs 4/202 (2%); Transurethral resection syndrome: 0/203 vs 0/203

ISRCTN00788389 · Report DOI

Design

Four university teaching hospitals and three district general hospitals enrolled men from July 23, 2014, to December 30, 2016. Eligible men had bothersome LUTS or urinary retention from benign prostatic obstruction, were suitable for TURP and had failed conservative and medical therapy. Exclusions were neurogenic LUTS, prostate cancer, previous prostate or urethral surgery, a prostate-specific antigen level outside the age-related range without cancer excluded, and inability to consent or complete trial documents. Prostate size was not an entry criterion and was estimated by digital rectal examination (median 35 g with ThuVARP and 40 g with TURP). About half the men were in retention: 213 of 406 (52%) were catheterized on the day of surgery, and 196 of 407 men analyzed at baseline presented with LUTS rather than retention.^[1]

Randomization was 1:1, stratified by centre and presentation (LUTS or retention), and was done at the point of surgery after the patient was anesthetized, so that patients stayed masked until follow-up ended and ward staff, theatre notes and discharge letters did not reveal the allocation. Surgeons and outcome assessors were not masked. Centres used their usual monopolar or bipolar TURP, and all trial surgeons were trained in ThuVARP and independently assessed before enrolling patients.^[1]

The co-primary endpoints were IPSS (0 to 35) and Qmax at 12 months. Equivalence was a difference of 2.5 points or less for IPSS and 4 mL/s or less for Qmax, based on minimally important differences in the literature. The target of 163 men per group with 12-month data gave 85% power for Qmax and just over 90% for IPSS at a two-sided alpha of 5%; allowing for 20% loss to follow-up, 410 men were needed. The primary analyses were intention to treat, adjusted for centre and baseline presentation, with multiple imputation of missing values. Baseline IPSS and Qmax could not be collected from catheterized men, so patient-reported outcomes were not adjusted for baseline. Complications within 12 months were graded by Clavien-Dindo class.^[1]

Results

At 12 months the mean IPSS was 6.43 after ThuVARP and 6.26 after TURP; the adjusted difference of 0.28 points (95% CI -0.92 to 1.49) lay within the 2.5-point margin, so the operations were equivalent for IPSS. Mean Qmax was 20.16 mL/s after ThuVARP and 23.24 mL/s after TURP (adjusted difference -3.12 mL/s, 95% CI -5.79 to -0.45). The lower confidence limit fell outside the 4 mL/s margin, so the operations were not equivalent for Qmax, and switching to superiority testing favored TURP. IPSS was completed by 310 of 410 men and Qmax recorded for 344.^[1]

Per-protocol and complier average causal effect analyses strengthened the intention-to-treat result, with an even larger Qmax advantage for TURP. No prespecified subgroup (age, LUTS versus retention, comorbidity, prostate size) changed the result. The TURP advantage looked larger in men presenting with LUTS, but the interaction tests were underpowered (p = 0.888 for IPSS, p = 0.189 for Qmax).^[1]

Median hospital stay was 48 hours in both arms (interquartile range 29 to 58 with ThuVARP and 29 to 61 with TURP; adjusted difference -3.28 hours, 95% CI -9.61 to 3.06). The IPSS storage and voiding subscores were similar. Nocturia more than once per night at 12 months was reported by 72 men (44%) after ThuVARP and 63 (37%) after TURP (odds ratio 1.47, 95% CI 0.93 to 2.34; p = 0.102), and p = 0.031 on the ordinal scale of 0 to 5 times per night. Post-void residual was higher after ThuVARP on an ordinal quintile analysis (odds ratio 1.46, 95% CI 1.00 to 2.15; p = 0.053), with 42 of 169 men (25%) in the highest quintile (141 to 1000 mL) versus 27 of 176 (15%) after TURP. Satisfaction scores (8.67 and 8.88 of 10) and the proportion who would definitely or probably have the same operation again (91% and 95%) did not differ.^[1]

In the exploratory histology analysis, prostate cancer was found in 10 of 193 men (5%) after ThuVARP and 25 of 193 (13%) after TURP (odds ratio 0.35, 95% CI 0.16 to 0.75). The median resected weight was 7 g after ThuVARP and 20 g after TURP.^[1]

Surgery and treatment delivery

ThuVARP used a LISA Revolix 120 W thulium laser with a 550 micrometer fibre to vaporize and resect the prostate in chips, a technique close to TURP. The median energy delivered was 148 kJ (interquartile range 120 to 197; range 20 to 987), recorded for 101 of 152 ThuVARP patients (66%). Before the trial the surgeons had done more than 100 TURPs but between 5 and 12 ThuVARPs.^[1]

Of 205 men allocated to ThuVARP, 152 (74%) had the laser operation; 48 received or converted to TURP, three received an alternative treatment, and two withdrew all data. Nine conversions to TURP were attributed to prostate size. Of 205 allocated to TURP, 200 (98%) had TURP. Mid-procedure conversion to TURP occurred in 13 of 94 laser procedures (14%) in surgeons' first half of cases and 22 of 90 (24%) in the second half, which the authors read as showing no learning-curve effect.^[1]

Median postoperative catheter time was 2 days in both arms (hazard ratio for removal 1.02, 95% CI 0.83 to 1.26).^[1] Hemoglobin fell by a median of 6 g/L after ThuVARP and 8 g/L after TURP (adjusted difference 0.88 g/L, 95% CI -2.14 to 3.89), and serum sodium by 2 and 3 mmol/L.^[1] In the cost-effectiveness analysis, the ThuVARP operation took on average 21 minutes longer than TURP.^[2]

Adverse events

At least one postoperative complication occurred in 96 of 203 men (47%) after ThuVARP and 91 of 204 (45%) after TURP (ordinal odds ratio 1.10, 95% CI 0.75 to 1.63; p = 0.623), and more than one in 68 (34%) and 64 (31%). Neither arm had transurethral resection syndrome. Transfusion was needed in 3 of 200 men (2%) after ThuVARP and 4 of 202 (2%) after TURP. Clot retention occurred in 9 of 199 (5%) versus 12 of 201 (6%) and bleeding that prompted a hemoglobin check in 11 of 199 (6%) versus 11 of 200 (6%), with one grade IIIb bleed in each arm. Urethral stricture occurred in 7 of 198 men (4%) after ThuVARP (four grade IIIa and three grade IIIb) and 5 of 200 (3%) after TURP (two grade I and three grade IIIb; odds ratio 1.43, 95% CI 0.45 to 4.59). Urinary tract infection occurred in 62 of 193 (32%) versus 64 of 200 (32%).^[1]

An indwelling catheter was still required at 12 months in 4 of 192 men (2%) after ThuVARP and 2 of 195 (1%) after TURP. By 12 months, 3 men in the ThuVARP arm and 2 in the TURP arm had a repeat TURP for obstruction.^[1]

Sexual symptoms were common before surgery and changed little. Reduced or no ejaculation was reported at 12 months by 129 men (93%) after ThuVARP and 136 (92%) after TURP, against 86% and 84% of non-catheterized men at baseline. In a post hoc analysis of men with LUTS, 22 of 70 with sexual dysfunction at baseline (31%) were worse, 32 (46%) unchanged and 16 (23%) improved, and 6 of 25 without baseline dysfunction (24%) developed mild to moderate symptoms. IIEF scores did not differ (14.18 versus 15.14), but only 218 of 410 men (53%) returned the questionnaire.^[1]

Limitations

Surgeons and outcome assessors were not masked; 238 of 342 patients who answered (70%) did not know which operation they had, and 34 (10%) learned it accidentally. Of 205 men allocated to ThuVARP, 152 (74%) received ThuVARP without conversion, 12 received TURP instead, 36 converted to TURP mid-procedure, three received another treatment and two withdrew all data; the authors addressed treatment deviations with per-protocol and complier average causal effect analyses. IPSS data were available for 76% of men and the primary analysis relied on imputation. Prostate volume was estimated by digital rectal examination, and the trial surgeons had far more experience of TURP than of ThuVARP. Follow-up ended at 12 months (repeat TURP in 3 versus 2 men), and 98% of the 400 participants with recorded ethnicity were white (393 of 400).^[1]

In conversation

• Parallel to WATER (2018). Another randomized comparison of an alternative BPH operation with TURP and a blinded patient-reported symptom endpoint; WATER tested robotic waterjet resection.

Same setting GOLIATH (2013), St Gallen PAE trial (2018)

WATER, another TURP-controlled trial on the BPH procedures timeline, studied 30 to 80 mL prostates and tested noninferiority of IPSS reduction at 6 months.^[4] UNBLOCS had no prostate-size limit, enrolled men in retention, and set equivalence margins on IPSS and Qmax at 12 months, so the two trials ask different questions of their TURP controls.

Guidelines and approvals

• EAU (March 2026). Offer laser vaporesection of the prostate using Tm:YAG laser (ThuVARP) as an alternative to transurethral resection of the prostate . The summary of evidence (level 1b) states that ThuVARP and TURP are equivalent for IPSS but not Qmax, with TURP deemed superior at 12 months, and that mid- to long-term results on efficacy and safety compared with TURP are very limited.^[3]

Report history

UNBLOCS report history

Published	Report	Cutoff	Headline results	Citation
2020-07-04	Primary report (12-month IPSS and Qmax) · primary	—	Mean IPSS at 12 months (ThuVARP minus TURP, adjusted for centre and baseline diagnosis): 6.43 vs 6.26; difference 0.28; CI -0.92–1.49 Met Mean Qmax at 12 months in mL/s (ThuVARP minus TURP, adjusted for centre and baseline diagnosis): 20.16 mL/s vs 23.24 mL/s; difference -3.12; CI -5.79–-0.45 Not met Median length of hospital stay in hours (IQR); adjusted difference ThuVARP minus TURP: 48 h (IQR 29 to 58) vs 48 h (IQR 29 to 61); difference -3.28; CI -9.61–3.06; P 0.310 Post-void residual at 12 months, ordinal analysis by quintile (odds ratio ThuVARP versus TURP): 42/169 (25%) in the highest quintile (141 to 1000 mL) vs 27/176 (15%) in the highest quintile (141 to 1000 mL); OR 1.46; CI 1–2.15; P 0.053 Nocturia more than once per night at 12 months (odds ratio ThuVARP versus TURP): 72 (44%) vs 63 (37%); OR 1.47; CI 0.93–2.34; P 0.102 IIEF total score at 12 months (adjusted difference ThuVARP minus TURP): 14.18 vs 15.14; difference -0.95; CI -2.95–1.05; P 0.348 ICIQ satisfaction score at 12 months, 0 to 10 (adjusted difference ThuVARP minus TURP): 8.67 vs 8.88; difference -0.21; CI -0.65–0.22; P 0.338 Prostate cancer diagnosed on routine histology of resected tissue (odds ratio ThuVARP versus TURP): 10/193 (5%) vs 25/193 (13%); OR 0.35; CI 0.16–0.75	Hashim H, Worthington J, Abrams P, et al. "Thulium laser transurethral vaporesection of the prostate versus transurethral resection of the prostate for men with lower urinary tract symptoms or urinary retention (UNBLOCS): a randomised controlled trial." *Lancet.* 2020;396(10243):50-61. doi:10.1016/S0140-6736(20)30537-7 DOI
2020-08-10	Cost-effectiveness analysis · secondary	—	Adjusted mean 12-month secondary care cost per patient (difference TURP minus ThuVARP): £4253 vs £4244; difference -9; CI -376–359 Adjusted mean QALY difference over 12 months (TURP minus ThuVARP, EQ-5D-5L): Favored TURP numerically; the interval includes zero.; difference 0.01; CI -0.01–0.04 Probability that TURP is the cost-effective option at £20,000 per QALY: 76%; — Descriptive	Noble SM, Ahern AM, Worthington J, et al. "The cost-effectiveness of transurethral resection of the prostate vs thulium laser transurethral vaporesection of the prostate in the UNBLOCS randomised controlled trial for benign prostatic obstruction." *BJU Int.* 2020;126(5):595-603. doi:10.1111/bju.15138 DOI

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References

1. Hashim H, Worthington J, Abrams P, et al. "Thulium laser transurethral vaporesection of the prostate versus transurethral resection of the prostate for men with lower urinary tract symptoms or urinary retention (UNBLOCS): a randomised controlled trial." Lancet. 2020;396(10243):50-61. doi:10.1016/S0140-6736(20)30537-7

2. Noble SM, Ahern AM, Worthington J, et al. "The cost-effectiveness of transurethral resection of the prostate vs thulium laser transurethral vaporesection of the prostate in the UNBLOCS randomised controlled trial for benign prostatic obstruction." BJU Int. 2020;126(5):595-603. doi:10.1111/bju.15138

3. Cornu JN, Elterman D, Hashim H, et al. EAU Guidelines on Non-Neurogenic Male Lower Urinary Tract Symptoms (LUTS). Arnhem: EAU Guidelines Office; March 2026. Section 5.3.1.c.

4. Gilling P, Barber N, Bidair M, et al. "WATER: A Double-Blind, Randomized, Controlled Trial of Aquablation® vs Transurethral Resection of the Prostate in Benign Prostatic Hyperplasia." J Urol. 2018;199(5):1252-1261. doi:10.1016/j.juro.2017.12.065