Quick Answer
Testosterone does not appear to simply “cause” prostate cancer, and medically supervised testosterone replacement has not been shown to increase prostate-cancer risk in hypogonadal men overall.
However, testosterone and other androgens can stimulate the growth of many existing prostate-cancer cells. That is why lowering testosterone or blocking androgen signaling is an important treatment for many men with recurrent, high-risk, advanced or metastatic prostate cancer.
If you already have prostate cancer or have been treated for it, testosterone replacement requires individualized specialist assessment rather than a routine decision.
The relationship between testosterone and prostate cancer is more complicated than the old idea that “more testosterone means more prostate cancer.”
There are really three separate questions:
- Does naturally high testosterone increase the risk of developing prostate cancer?
- Does testosterone replacement therapy, or TRT, cause prostate cancer?
- Why do doctors lower testosterone when treating some prostate cancers?
These questions need different answers.
What Is Testosterone?
Testosterone is the main circulating male androgen. Most is produced in the testicles, with smaller amounts of androgen precursors coming from the adrenal glands.
Within prostate tissue, testosterone can also be converted into dihydrotestosterone, or DHT. Both testosterone and DHT can activate the androgen receptor.
Androgen signaling is important for normal prostate function, but it is also important in the biology of many prostate cancers.
Does High Testosterone Cause Prostate Cancer?
Current evidence does not support the simple idea that men with higher testosterone levels automatically have a higher risk of developing prostate cancer.
Large observational studies and pooled analyses have not shown a straightforward relationship in which increasing circulating testosterone produces a proportional increase in prostate-cancer risk.
Prostate cancer is influenced by many factors, including age, inherited susceptibility and ancestry, rather than being explained by testosterone level alone.
Saying testosterone does not appear to directly cause prostate cancer is not the same as saying prostate cancer is independent of testosterone. Many established prostate cancers remain highly dependent on androgen-receptor signaling for growth.
Does Testosterone Replacement Therapy Cause Prostate Cancer?
For men who have medically confirmed hypogonadism, current evidence has not shown that appropriately prescribed testosterone replacement therapy increases the overall risk of developing prostate cancer.
However, this does not mean testosterone can be taken without medical evaluation or monitoring.
Before starting TRT, a clinician usually considers symptoms, confirmed testosterone levels, age, prostate history and other health factors. Depending on the man’s age and risk profile, PSA assessment and prostate evaluation may also be appropriate.
Long-term prospective safety data are still less extensive than clinicians would ideally like, so monitoring remains important.
Can a Man With Prostate Cancer Take Testosterone?
This is much more complicated.
Active prostate cancer is generally a major reason for caution with testosterone therapy. Testosterone treatment should not be started casually in a man with known prostate cancer because many prostate-cancer cells are stimulated by androgen signaling.
After successful treatment for localized prostate cancer, some men who remain significantly hypogonadal may eventually be considered for testosterone therapy under specialist supervision.
The decision depends on factors such as:
- the original Grade Group or Gleason score
- the cancer stage
- how the cancer was treated
- PSA results over time
- whether there is any evidence of recurrence
- how long the patient has remained disease-free
- severity of testosterone-deficiency symptoms
- the individual’s overall health and preferences
Why Do Doctors Lower Testosterone to Treat Prostate Cancer?
Many prostate cancers depend on androgens for growth.
Testosterone and DHT bind to the androgen receptor inside prostate cells. Activation of this receptor can stimulate genes involved in prostate-cell growth and survival.
For that reason, one of the major strategies in prostate-cancer treatment is to reduce androgen levels or interfere with androgen-receptor signaling. This is called androgen-deprivation therapy, or ADT.
When Is Androgen-Deprivation Therapy Used?
ADT is not automatically necessary for every prostate cancer.
Depending on the cancer, it may be used:
- with radiation therapy for selected intermediate-risk or high-risk localized cancers
- for some cancers that recur after surgery or radiation
- for locally advanced prostate cancer
- as a central component of treatment for metastatic prostate cancer
- to control symptoms in selected advanced disease
For metastatic hormone-sensitive prostate cancer, treatment often combines ADT with another systemic therapy rather than relying on testosterone suppression alone.
How Is Testosterone Lowered?
Several treatment approaches can suppress androgen production.
| Treatment approach | How it works |
|---|---|
| GnRH/LHRH agonists | Initially stimulate and then suppress signals from the pituitary gland that normally stimulate testosterone production. |
| GnRH antagonists | Block the hormonal signal more directly and reduce testosterone without the initial testosterone flare associated with agonists. |
| Orchiectomy | Surgical removal of the testicles produces a rapid and substantial reduction in circulating testosterone. |
Examples of GnRH agonists include leuprolide, goserelin and triptorelin. GnRH antagonists include degarelix and oral relugolix.
What Is a Testosterone Flare?
When a GnRH agonist is first given, testosterone can temporarily rise before falling to very low levels.
This is known as a testosterone flare.
In some men with advanced prostate cancer, a flare can temporarily worsen problems such as bone pain, urinary obstruction or, in particularly high-risk situations, spinal cord compression.
Doctors therefore take the disease pattern into account when selecting an ADT strategy and may use additional medication when flare prevention is clinically important.
What Are Antiandrogens?
Some prostate-cancer medicines do not primarily lower testosterone. Instead, they interfere with the androgen receptor so testosterone and DHT cannot stimulate the cancer cells as effectively.
Older androgen-receptor blockers include bicalutamide and flutamide.
More potent newer androgen-receptor pathway inhibitors include medicines such as:
- enzalutamide
- apalutamide
- darolutamide
These medicines are used in specific prostate-cancer settings, often together with ongoing ADT.
What Does Abiraterone Do?
Abiraterone works differently. It inhibits an enzyme involved in androgen production and can suppress androgen synthesis not only in the testicles but also in the adrenal glands and prostate-cancer tissue.
It is used in selected advanced prostate cancers and is generally given together with corticosteroid treatment such as prednisone.
The exact combination depends on the stage and characteristics of the disease.
Does Hormone Therapy Cure Prostate Cancer?
The answer depends on how hormone therapy is being used.
ADT by itself generally does not cure metastatic prostate cancer. It can substantially suppress the disease and may control it for prolonged periods.
In localized higher-risk disease, however, ADT may be combined with radiation therapy as part of a treatment strategy intended to cure the cancer.
So it is too simplistic to say that hormone therapy can “never cure” prostate cancer.
What Happens When Prostate Cancer Grows Despite Low Testosterone?
Some prostate cancers eventually progress even though testosterone has been suppressed to very low levels. This is called castration-resistant prostate cancer.
This does not mean the cancer has become completely independent of androgens.
Androgen-receptor signaling can remain important, which is why treatments such as abiraterone, enzalutamide or other androgen-pathway medicines can still be effective in selected men.
Patients with metastatic castration-resistant disease generally continue ADT while additional treatments are added according to the characteristics of their cancer.
What About Giving High-Dose Testosterone to Prostate Cancer Patients?
This sounds contradictory, but researchers have investigated carefully controlled exposure to very high and very low testosterone levels in selected men with advanced prostate cancer.
One experimental approach is known as bipolar androgen therapy.
Early studies suggest that rapid cycling between high and low testosterone levels may affect certain resistant prostate-cancer cells and, in some cases, may restore sensitivity to androgen-receptor treatments.
However, this is a specialized and still evolving treatment strategy. It is not the same as ordinary testosterone replacement therapy and should not be attempted outside appropriate specialist management or clinical-trial settings.
What Are the Main Risk Factors for Prostate Cancer?
Testosterone is only one part of the discussion. Several much more clearly established factors influence prostate-cancer risk.
Increasing age
Risk rises substantially with age, particularly after middle age.
Family history and inherited genes
Having a father or brother with prostate cancer can increase risk, particularly when several close relatives are affected or cancer developed at a younger age.
Inherited changes in genes involved in DNA repair, including BRCA2 and some other hereditary cancer genes, can also increase prostate-cancer risk and may influence how the cancer behaves.
Ancestry
Men of African ancestry have a higher incidence of prostate cancer and are more likely to develop aggressive disease than many other populations. The causes are complex and likely involve a combination of genetic, environmental, healthcare and socioeconomic factors.
Other factors
Researchers continue to study obesity, diet, inflammation, environmental exposures and other potential contributors. The evidence for these factors is less straightforward than for age, ancestry and inherited susceptibility.
Does Testosterone Raise PSA?
PSA production is influenced by androgen signaling, so starting testosterone therapy can sometimes produce a modest change in PSA, particularly when a man previously had very low testosterone.
That does not automatically mean prostate cancer has developed.
However, a substantial or unexpected PSA rise should be appropriately investigated rather than dismissed. PSA always needs interpretation in context.
You can read more in my guide to PSA and prostate testing.
Should Testosterone Be Checked in Men With Prostate Cancer?
In men receiving ADT, testosterone measurement can be clinically useful because the treatment is intended to suppress androgen levels.
If PSA begins rising despite treatment, doctors may check whether testosterone has been adequately suppressed and evaluate whether the disease has become castration-resistant.
This is different from routine testosterone screening in every man who is being evaluated for prostate cancer.
The most useful way to understand testosterone and prostate cancer is to avoid two extremes. Testosterone does not appear to be a simple cause of prostate cancer, so men with genuine hypogonadism should not automatically be told that medically supervised testosterone replacement will cause cancer. On the other hand, testosterone is biologically important to many established prostate cancers, which is why lowering or blocking androgen signaling remains one of our most important treatment strategies. A man’s cancer status changes the clinical question completely.
European Association of Urology. Guidelines on Prostate Cancer: Epidemiology and Aetiology.
European Association of Urology. Guidelines on Male Hypogonadism.
National Cancer Institute. Hormone Therapy for Prostate Cancer.
National Cancer Institute. Prostate Cancer Treatment (PDQ).