TRAVERSE randomized more than 5,200 men with existing heart disease or high cardiovascular risk and followed them for around three years. It was designed to answer the cardiovascular question, and it reported on prostate outcomes as well. It did not find the increase in prostate cancer that fifty years of caution had assumed.
This is the fear men arrive with, and it comes from real medicine rather than from the internet, which is why it deserves a serious answer rather than a reassuring one.
Where the fear came from
In the 1940s it was shown that lowering testosterone dramatically shrank advanced prostate cancer. Removing the hormone made established cancer regress. That observation was correct, it changed cancer treatment, and it earned a Nobel Prize.
The leap that followed was the problem. If taking testosterone away shrinks a cancer, adding it must grow one. That inference held for decades on very little direct evidence, and it kept a lot of men untreated who did not need to be.
What the large trial found
TRAVERSE was built to settle the cardiovascular safety question in men who already had heart disease or were at high risk of it, which is the group where the stakes are highest. Alongside the cardiac endpoints, it tracked prostate events.
The trial did not find the excess of prostate cancer that the old assumption predicted.
That is a meaningful result, and it is worth being precise about why. It is a randomized comparison rather than an observation. It ran for around three years in more than five thousand men. That is a strong answer to the question it asked.
What it did not settle
Three years is not a lifetime. Prostate cancer is frequently slow, and a trial of that length cannot exclude an effect that would only appear over a much longer horizon.
It also excluded men who already had prostate cancer, and men with strongly suspicious findings before entry. So it does not tell you what happens if you give testosterone to a man with an undiagnosed cancer already present, which is exactly why the assessment before treatment matters more than the reassurance after it.
Anyone who tells you the prostate question is now closed is going further than the evidence does.
What actually happens to the prostate
Testosterone treatment commonly produces a modest rise in PSA in the first months, as the prostate responds to a hormone level it has not seen for some time. That is expected and it is not in itself alarming.
What matters is the pattern rather than a single value. A rise that continues, a rise that is steep, or a change in the gland on examination are the findings that lead somewhere. That is why PSA is checked before starting and monitored afterwards, and why an unexplained rise is investigated rather than watched.
Enlargement is a different question
Benign enlargement of the prostate, the kind that affects the urinary stream rather than being cancer, is a separate issue and men frequently confuse the two. Existing lower urinary tract symptoms are assessed before treatment, monitored during it, and are one of the reasons a man might be advised against starting or advised to have the urology side looked at first.
A weak stream is not a cancer. It is also not something to discover for the first time three months into treatment.
The part that decides it
None of the above works without the assessment beforehand. A baseline PSA. An examination. A proper history, including family history, which changes the threshold for everything.
That is the difference between a specialist assessment and a hormone handed out on the basis of a symptom questionnaire. The trial evidence is reassuring about the population. It says nothing about whether you personally were checked before anyone started.
The rest of what that trial found is in is testosterone therapy safe, honestly. The other value that moves on treatment is in what happens to your blood count.
Lincoff AM, et al. "Cardiovascular Safety of Testosterone-Replacement Therapy." New England Journal of Medicine, 2023. doi:10.1056/NEJMoa2215025
Bhasin S, et al. "Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline." The Journal of Clinical Endocrinology and Metabolism, 2018. doi:10.1210/jc.2018-00229