Benign prostate obstruction (BPO) can be treated with a range of laser treatments using different laser systems and applications. Transurethral laser treatment is considered to be an alternative treatment to transurethral resection of the prostate (TURP). The latest guidelines of the European Association of Urology recommend 532-nm GreenLight laser vaporisation of the prostate and thulium laser enucleation as alternatives to TURP. For further investigation of the efficacy of GreenLight and thulium laser in treating BPH, the investigators organize a prospective randomised control study. The investigators will enrol 100 patients with BPO, treated with either GreenLight laser or thulium laser prostatectomy, and compare their safety and efficacy.

80 patients with symptomatic benign prostate obstruction (BPO) will be assigned under randomization to treat with GreenLight laser or thulium laser. Randomization is performed by free randomization software.

Inclusion criteria are patient age greater than 50 years, maximum flow rate (Qmax) < 15 ml/second and an International Prostate Symptom Score (IPSS) ≥ 10. The data for the quality-of-life questionnaire (QoL) and transrectal ultrasound measurement of the prostate (TRUS) are obtained preoperatively.

Exclusion criteria are known prostate cancer, bladder cancer, previous transurethral surgery, interstitial cystitis and neurogenic bladder confirmed after urodynamic studies. The use of anticoagulants or platelet aggregation inhibition and urinary retention under catheterization is not a criterion for study exclusion. The local institutional review board committee has approved the study as well as the data analysis.

Sample size The sample size was determined based on an expected mean IPSS of 5.8 ± 2.6 at 1-year followup. The investigators considered a change of deference of IPSS ≤ 2 as an accepted equivalence between the two groups. The sample size was calculated to be at least 21 patients in each group with α=0.05, β=0.80 and a desired statistical power level of 80%. Considering the possibility of patients drop out or lost to followup, 40 patients will be enrolled in each arm. All measurement data will be presented as mean ± standard deviation.

Statistical analysis StataCorp Stata 15 was used for statistical analysis. The Fisher's exact test was applied to compare categorical variables; and the Student's t-test was used to compare quantitative variables between the two treatment groups. A mixed model with random effect and Bonferroni correction was applied to compare IPSS, QoL, Qmax, and PVR between two groups. A two-sided P-value of < 0.05 was considered statistically significant.

Inclusion Criteria:

• Inclusion criteria are patient age greater than 50 years, maximum flow rate (Qmax) < 15 ml/second and an International Prostate Symptom Score (IPSS) ≥ 10.

Exclusion Criteria:

• Exclusion criteria are known prostate cancer, bladder cancer, previous transurethral surgery, interstitial cystitis and neurogenic bladder confirmed after urodynamic studies.