Enucleation Ratio as a Novel Predictor of Symptomatic Improvement After HoLEP

Predictive Value of Enucleation Ratio for Symptomatic Improvement After HoLEP: A Multicenter Prospective Cohort Study

The goal of this observational study is to determine whether the rate of prostate tissue removed during surgery relative to the preoperative total prostate volume (referred to as the "enucleation ratio") predicts symptomatic improvement 3 months after HoLEP. The main question it aims to answer is:

- What is the minimum enucleation ratio required to achieve clinically important symptomatic improvement? (Symptomatic improvement is referred to as a threshold of having an International Prostate Symptom Score (IPSS) lower than 8 points, which is determined by the American Urological Association (AUA) and European Association of Urology(EAU)).

HoLEP has become a widespread and well-practiced surgical method for benign prostate obstruction (BPO). The method is known to have a steep learning curve, and mastery requires extensive practice. Treatment efficiency depends on removing the obstruction while protecting the delicate external urethral sphincter.

However, it's still unclear which pre-operative and intra-operative factors affect surgical outcome. Some authors have already contributed to this subject; in fact, changes in peak urinary flow rate, IPSS-QoL, and the absence of stress urinary incontinence and high-grade complications are among the agreed-upon criteria for successful surgery. As the main purpose of HoLEP, or any other benign prostate surgeries, is to remove obstruction, the more adenoma tissue to be removed, the less obstruction there will be. Yet not anatomic, but there's a surgical capsule around the prostate, which can stretch, causing residual tissue to obstruct the urethral passage. Leaving residual adenoma tissue is not uncommon and may affect the efficacy of HoLEP, particularly given the steep learning curve of the procedure. Therefore, it may be reasonable for one to consider that the higher the ratio of adenoma tissue removed, the better the outcomes could be.

Enucleation ratio is a novel parameter that has not been investigated previously in this context and is calculated by dividing the weight (grams) of morcellated adenoma tissue by the preoperatively measured prostate volume (mL). The density of the prostate is widely accepted as 1 gram per milliliter, so the enucleation ratio has no units.

Identifying a minimum enucleation ratio associated with clinically meaningful symptomatic improvement could provide surgeons with a measurable intraoperative target, potentially improving procedural standardization and patient counseling - particularly during the learning curve of HoLEP.

Inclusion Criteria:

• Men aged 18 years pr older who are planned to undergo HoLEP.
• Participants who are willing to give informed consent.
• Participants who have moderate to severe LUTS (referring to IPSS score 8 points or more).
• No history of previous prostate or urethral surgery.

Exclusion Criteria:

• Unwillingness to provide informed consent.
• Unwillingness to provide contact information or unreachability during follow-up periods.
• Incidental diagnosis of a urogenital malignancy requiring primary treatment after enrollment (e.g., bladder tumor, renal cell carcinoma, testicular tumor).