Sydney siege survivor undergoes life-prolonging prostate cancer surgery

Sydney siege survivor John O'Brien has returned home after life-prolonging surgery to stave off aggressive prostate cancer.

The former tennis pro and coach was rocked by the diagnosis, fearing he would no longer be around to care for his ill wife and daughter who suffers from severe bipolar disorder.

"That's my worst fear, what would become of them and how they'd manage," Mr O'Brien told A Current Affair.

Renowned urologist, Professor Phillip Stricker, performed brachytherapy, which involves inserting radioactive seeds directly into the prostate to target the tumour.

"Brachytherapy has evolved. So in the beginning, we didn't have quite the quality control in terms of accuracy. With modern technology and some of the computer software, we are more accurately able to place the seeds," Professor Stricker said.

Mr O'Brien received 66 seeds, which will fight the tumour over the next few months.

"It went well," Professor Stricker said.

"I put the seeds in and sort of covered the high-grade cancer area and in a couple of months, he will get the external beam to smooth out the edges and make sure the dose is high enough."

Mr O'Brien's wife, Maureen, is pleased to have her husband back at home with her.

"He will be around for a lot longer," Mrs O'Brien said.

Remarkably, Mr O'Brien is hoping he will be fit enough to take part in the Australian Tennis Seniors Championships in Adelaide in January.