Testosterone replacement therapy (TRT) continues to be controversial in males who have previously had prostate cancer. In that study, 1303 patients who underwent robotic-assisted radical prostatectomy from 2006 to 2009. The researchers then separated the men into 2 main groups- those exhibiting low testosterone and those with normal levels of testosterone. 3.6 percent of the men undertook Testosterone replacement therapy, and they found that 2 years later, 6.4% of the TRT group got a Biochemical recurrence (BCR) of cancer, but in the non treated group- almost twice as many males (12.56%) has the BCR. In addition to having half the rate of cancer reoccurrence- a there was another benefit, those men on TRT has a significant positive change their Sexual Health Inventory for Men test.
So it shows that carefully monitored men with previous prostate cancer had a incidence rate of reoccurrence of half vs those that did not have TRT. Study link- Oncological safety and functional outcomes of testosterone replacement therapy in symptomatic adult-onset hypogonadal prostate cancer patients following robot-assisted radical prostatectomy