He has subspecialty expertise in kidney cancer, bladder cancer, and testis cancer. He receives large numbers of referrals from all over the south of England for complex kidney cancer surgery, in particular removal of very large life-threatening kidney cancers which have invaded the inferior vena cava or the heart. He has a wealth of experience having performed over 800 complex nephrectomies. He also performed over 350 partial nephrectomies (kidney cancer removal with preservation of kidney function) and has particular expertise in the treatment of kidney cancer in solitary kidneys. He has taught on these techniques nationally and in Europe, Australia and the USA.
He is the surgeon in the Guy’s unit who performs the retroperitoneal lymph node dissections (RPLND) for men with residual testis cancer after intensive chemotherapy.
Mr O’Brien runs the retroperitoneal fibrosis (RPF) service with Ms Archie Fernando and Dr James Pattison. This specialist service was established in 2012 and the multidisciplinary care offered is probably unique in the UK. The clinic has been a great success and in 2016 the 150th patient was seen for assessment. The team have built up very significant expertise in ureterolysis so that over 60 patients have now undergone this complex operation. A patient forum has been established and the team are actively involved in research in the disease.
In bladder cancer his team have developed and improved the techniques of blue light cystoscopy (photodynamic assisted resection PDD) and sequential intravesical EMDA Mitomycin with BCG, techniques which aim to improve the completeness of bladder cancer treatment whilst preserving bladder function. The team have published numerous papers on the techniques; won a prestigious award from the European Association of Urology for their research ; and Mr O’Brien was invited in 2010 to the FDA in Washington DC to make the case for approval of PDD in the United States.
He led the team that developed the urology centre at Guy’s. This multi-million pound award winning out-patient project has transformed the way urology patients are assessed and treated at Guy’s and St Thomas’. The development of the centre has led to an interest in quality improvement in Urology.
From 2010-14, Mr O’Brien was Chairman of the section of oncology of the British Association of Urological Surgeons (BAUS). In this role he led national efforts to improve urological cancer surgery and was the lead author on publications examining the quality of partial nephrectomy and RPLND across the UK.
In 2013, he was elected to the Scientific Congress Office of the European Association of Urology.