Robotic prostatectomy (RARP) is a surgery for treatment localized prostate cancer. Bilateral pelvic lymph node dissection (BPLND) will also be performed if there is an estimated risk of occult nodal metastases exceeding 5%. BPLND in general is a well-tolerated procedure. Lymphatic leak is one of the possible complications after lymph node dissection (BPLND). Lymphocele is a collection of lymphatic fluid after operation. Hemopatch is a material used during operation that may prevent lymphorrhoea. This is a randomizedcontrolled trial that aims at investigating the application of Hemopatch to raw lymphatic tissue in preventing lymphorrhoea. Patients would be divided into 2 groups: with or without the use of Hemopatch during operation. They will be followed up on day 30 to monitor the course of recovery and any complications.

In prostate cancer patients undergoing robot-assisted radical prostatectomy (RARP), the current European Association of Urology (EAU) prostate cancer guidelines recommend bilateral pelvic lymph node dissection (BPLND) for those with an estimated risk of occult nodal metastases exceeding 5%.(1) In a systematic review of 66 studies involving 275, 269 patients, lymphadenectomy can identify node positive patients who may benefit from adjuvant treatment (2).

BPLND in general is a well-tolerated procedure. However, when complications do occur, significant morbidity results. The benefits of BPLND must be carefully weighed against its potential complications. The most common complication of BPLND is lymphocoele formation. Lymphatic vessels have no muscular layer as opposed to blood vessels. Transection of a blood vessel will lead to vasoconstriction and eventual cessation of bleeding. This is not the case with lymphatic vessels, and transection will lead to prolonged lymphorrhoea. The incidence of lymphocoele varies from series to series, ranging from 0.8% to 33%, depending on the extent of lymphadenectomy, surgical technique, operative approach, and the diagnostic approach (3,4). The most common symptoms are pelvic pain, abdominal distension, lower extremity or scrotal oedema, lower urinary tract symptom, frank bladder outlet obstruction, sepsis and even anastomotic disruption. Prolonged lymphorrhoea lengthens hospital stay, places the patient at risk for nosocomial infection and has significant cost implications for the healthcare system.

Hemopatch is a haemostatic pad consisting of a collagen sheet derived from bovine dermis with an NHS-PEG (pentaerythritol polyethylene glycol ether tetra-succinimidyl glutarate) coated active surface. These two components act together to provide effective tissue adherence, sealing and haemostasis (5). Upon tissue contact, NHS-PEG molecules on the active surface form covalent bonds with tissue proteins. Cross-linking NHS-PEG and proteins forms a hydrogel which acts as an effective tissue seal. Older generation NHS-PEG products in the form of solutions of flowable sealants are quickly washed away by blood or other leaking body fluids, rendering them ineffective in the presence of active bleeding or fluid leakage. Hemopatch is a novel NHSPEG delivery vehicle designed to overcome this limitation. Due to the open pore structure of the collagen, excess tissue fluids are readily absorbed and direct contact of NHS-PEG to tissue surface can be achieved. The collagen pad is optimized to be soft, thin, pliable, and has a high liquid absorption capacity. The pad is resorbed and replaced by host tissue in six to eight weeks with little tissue reaction.

The investigators hypothesise that the application of Hemopatch to raw lymphatic tissue can prevent lymphorrhoea through its unique combination of tissue adherence, sealing and fluid absorption. This can potentially prevent lymphatic leak, reduce drain output and facilitate earlier discharge.

Inclusion Criteria:

• Age 18 years and above
• Able to give informed consent
• Suitable for minimally-invasive surgery

Exclusion Criteria:

• Known allergy or hypersensitivity to any component of Hemopatch®
• Known hypersensitivity to bovine proteins or brilliant blue
• Patients with prior pelvic radiotherapy
• Patients with non-correctable coagulopathy
• Patients who are on anticoagulants
• Contraindication to general anaesthesia
• Previous transurethral resection of the prostate or prostatic surgery
• Untreated active infection

Patients are randomized to receive RARP and BPLND, with or without Hemopatch, with an allocation ratio of 1:1.