Does Low Testosterone Increase Prostate Cancer Risk?

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Medically Approved by Dr Aqua Asif (Jun 18th 2025) and Mr Raj Nigam Consultant Urologist GMC: 3265226. (20/3/2026)

Written by FTC Medical Team

At a Glance

Current research — including a collaborative analysis of 20 prospective studies involving approximately 19,000 men — suggests that very low testosterone does not increase prostate cancer risk and may actually reduce it. However, when cancer does develop in men with low testosterone, it tends to be more aggressive. Testosterone replacement therapy (TRT), when properly supervised, does not appear to raise cancer risk.

• Low testosterone may reduce risk — large studies show men with very low free testosterone are less likely to be diagnosed with prostate cancer (Watts et al., European Urology, 2018)
• Aggressive cancer link — if cancer develops in men with low testosterone, it may present as a more aggressive form requiring closer monitoring
• TRT appears safe — current evidence suggests properly monitored testosterone replacement therapy does not increase prostate cancer risk
• Regular screening matters — men over 50, or from age 45 with risk factors, should discuss PSA testing and prostate health with their GP
• Specialist assessment available — The Focal Therapy Clinic’s consultant urological surgeons can assess prostate concerns alongside hormone health

The relationship between testosterone levels and prostate cancer risk is more nuanced than many men expect. A collaborative analysis of 20 prospective studies involving approximately 19,000 men (Watts et al., European Urology, 2018) found that very low testosterone does not increase prostate cancer risk — and may even reduce it. However, when cancer does develop in men with low testosterone, it tends to be more aggressive. Understanding these findings can help men on testosterone replacement therapy (TRT) or with low hormone levels make informed decisions about prostate monitoring.

What is testosterone and why it is important

Testosterone is the primary male sex hormone, responsible for sexual function, muscle mass, bone density, energy levels, mood, and cognitive function. Levels naturally decline with age — most men lose approximately 1-2% of their testosterone per year after age 30 — and symptoms of low testosterone (hypogonadism) affect an estimated 2-6% of men aged 40-79 according to the British Society for Sexual Medicine (BSSM) guidelines (2023).

What Are Normal and Low Testosterone Levels?

In the UK, normal total testosterone levels typically range from 8-30 nmol/L, though laboratories may use slightly different reference ranges. The BSSM defines testosterone deficiency as a total testosterone below 8 nmol/L, with levels between 8-12 nmol/L considered borderline.

Common symptoms of low testosterone include:

• Reduced sexual function — lower libido, erectile difficulties
• Physical changes — loss of muscle mass, increased body fat, reduced bone density
• Mood and energy — fatigue, low mood, difficulty concentrating

If you are experiencing these symptoms, a morning blood test (testosterone levels are highest in the morning) can help your GP determine whether low testosterone is contributing.

What Is Prostate Cancer and Who Is Most at Risk?

Prostate cancer is the most common cancer in men in the United Kingdom, with approximately 52,000 new cases diagnosed each year (NICE guideline NG131). The prostate is a walnut-sized gland located below the bladder that produces fluid to nourish sperm. When cells in the prostate grow abnormally, prostate cancer can develop — though many cases are slow-growing and treatable.

What Are the Main Risk Factors?

Several factors increase prostate cancer risk:

• Age over 50 — the majority of cases are diagnosed in men over 50, with risk increasing with age
• African Caribbean heritage — Black men have approximately twice the risk of developing prostate cancer compared to other ethnic groups (Prostate Cancer UK)
• Family history — a family history of prostate cancer or breast cancer (particularly BRCA2 gene mutations) increases risk

Men in these higher-risk groups should consider earlier screening — from age 45 rather than 50.

What Symptoms Should You Watch For?

Early prostate cancer often causes no symptoms, which is why proactive screening is important. As the disease progresses, men may notice:

• Urinary changes — difficulty starting or stopping urination, weak flow, or increased frequency
• Blood in urine or semen — always requires investigation
• Pelvic or lower back pain — may indicate locally advanced disease

If you experience any of these early symptoms of prostate cancer, see your GP as soon as possible.

Is There a Link Between Low Testosterone and Prostate Cancer?

Large-scale research has found no consistent link between testosterone levels and increased prostate cancer risk. A collaborative analysis of 20 prospective studies involving approximately 19,000 men found that those with very low free testosterone had a lower risk of prostate cancer diagnosis — but when cancer did develop, it was more likely to be aggressive (Watts et al., European Urology, 2018). This challenges the older assumption that testosterone “fuels” prostate cancer growth.

What Do the Key Studies Show?

The most significant research on testosterone and prostate cancer risk includes:

The Saturation Model: Why More Testosterone May Not Mean More Risk

The “saturation model,” proposed by Morgentaler and Traish (European Urology, 2009), provides a key explanation. Once testosterone reaches a normal threshold, prostate tissue becomes “saturated” — meaning additional testosterone does not stimulate further growth or increase cancer risk. This model explains why men with normal or even high testosterone levels are not necessarily at greater risk than those with moderately low levels.

This has important implications for men considering testosterone replacement therapy, as it suggests that restoring testosterone to normal levels should not increase cancer risk.

Is Testosterone Replacement Therapy Safe for Prostate Cancer Risk?

Current evidence, including data from the Testosterone Trials (Snyder et al., New England Journal of Medicine, 2023), suggests that testosterone replacement therapy (TRT) does not increase prostate cancer risk in men without a history of the disease. The British Society for Sexual Medicine (BSSM) guidelines (2023) support this position, recommending that TRT can be safely prescribed with appropriate monitoring.

However, men receiving TRT should have regular PSA testing and prostate assessment. If you have concerns about prostate health alongside low testosterone, The Focal Therapy Clinic’s consultant urological surgeons can provide specialist assessment of both hormone and prostate health.

“Men with low testosterone who are concerned about prostate cancer should not delay seeking assessment. A thorough evaluation — including PSA testing, MRI where indicated, and specialist review — can provide clarity and peace of mind, regardless of hormone levels.”

When Should You Get Tested?

Regular prostate and hormone monitoring is important for men over 50 — or from age 45 if you have risk factors such as a family history of prostate cancer or African Caribbean heritage. Early detection through PSA testing and hormone assessment can identify issues before symptoms develop.

Who Should Consider Testing?

Speak with your GP about testosterone and prostate testing if you:

• Are over 50 — and have concerns about prostate health or low testosterone symptoms
• Are over 45 with risk factors — including family history of prostate or breast cancer, or African Caribbean heritage
• Have low testosterone symptoms — such as fatigue, reduced libido, mood changes, or loss of muscle mass
• Are on or considering TRT — testosterone replacement therapy requires regular prostate monitoring, as recommended by the BSSM guidelines (2023)

What Tests Are Available?

In the UK, men can request a PSA (prostate-specific antigen) test from their GP to help assess prostate health, though the NHS does not currently offer routine prostate cancer screening (NHS, PSA test). PSA levels can be elevated by several prostate conditions, not only cancer, so results should be interpreted carefully.

Importantly, low testosterone can suppress PSA readings — meaning men with very low testosterone may have artificially low PSA values that could mask prostate conditions. When starting TRT, PSA levels typically rise as testosterone returns to normal. This is why the BSSM guidelines recommend PSA testing before starting TRT and at regular intervals during treatment.

Hormone panels measure testosterone alongside related hormones. These tests, combined with PSA monitoring, should be interpreted by experienced specialist urologists who understand the interaction between hormone levels and prostate health.

How Can You Protect Your Prostate and Hormone Health?

While risk factors like age and genetics cannot be changed, evidence-based lifestyle choices can support both prostate and hormone health. Research suggests that maintaining a healthy weight, staying active, and eating well may reduce prostate cancer risk and help support healthy testosterone levels.

What Lifestyle Changes Support Prostate Health?

Prostate Cancer UK and current evidence support the following diet and lifestyle habits:

• Eat a plant-rich diet — include plenty of vegetables, particularly tomatoes (rich in lycopene) and cruciferous vegetables like broccoli
• Choose oily fish regularly — salmon, mackerel, and sardines provide omega-3 fatty acids linked to prostate health
• Limit red and processed meat — high consumption is associated with increased cancer risk
• Stay physically active — aim for at least 150 minutes of moderate exercise weekly, which also supports healthy testosterone levels
• Maintain a healthy weight — obesity is linked to both low testosterone and more aggressive prostate cancer
• Avoid smoking and limit alcohol — both can negatively affect hormone balance and overall health

When Should You Seek Specialist Advice?

If you have concerns about testosterone levels, prostate health, or are considering testosterone therapy, discuss these with your GP or a specialist urologist. For men who have been diagnosed with prostate cancer — including those with a history of low testosterone — The Focal Therapy Clinic offers a range of treatment options including focal therapy, which targets cancer while preserving surrounding healthy tissue. You can also request a second opinion on an existing diagnosis or treatment plan.

FAQs

Does low testosterone cause prostate cancer?

No — current evidence does not support a causal link between low testosterone and prostate cancer. A collaborative analysis of 20 prospective studies involving approximately 19,000 men (Watts et al., European Urology, 2018) found that men with very low free testosterone actually had a reduced risk of prostate cancer diagnosis. However, when cancer did develop in men with low testosterone, it was more likely to present as an aggressive form requiring closer monitoring.

Separately, a collaborative analysis of 18 prospective studies (Endogenous Hormones and Prostate Cancer Collaborative Group, JNCI, 2008) found no clear association between higher testosterone levels and increased cancer risk. The relationship between testosterone and prostate cancer is complex, but the evidence is reassuring for most men.

Does low testosterone affect PSA?

Yes — testosterone levels directly influence PSA (prostate-specific antigen) readings. Men with very low testosterone may have artificially low PSA values, which could mask underlying prostate conditions. When starting testosterone replacement therapy (TRT), PSA levels typically rise as testosterone returns to normal levels. The British Society for Sexual Medicine guidelines (2023) recommend PSA testing before starting TRT and at regular intervals during treatment — typically at 3-6 months and then annually. If your PSA rises significantly after starting TRT, your doctor should refer you to a specialist urologist for further investigation.

References

The British Society for Sexual Medicine Guidelines on Male Adult Testosterone Deficiency. Sexual Medicine. 2023;41(3):508-537.

Endogenous Hormones and Prostate Cancer Collaborative Group. Endogenous sex hormones and prostate cancer: a collaborative analysis of 18 prospective studies. J Natl Cancer Inst. 2008;100(3):170-83.

Snyder PJ, et al. Cardiovascular Events in the Testosterone Trials. N Engl J Med. 2023;389(2):107-117.

NHS. PSA test. Available at: https://www.nhs.uk/conditions/psa-test/

Prostate Cancer UK. Black men and prostate cancer. Available at: https://prostatecanceruk.org/prostate-information-and-support/risk-and-symptoms/black-men-and-prostate-cancer

Morgentaler A, Traish AM. Shifting the paradigm of testosterone and prostate cancer. Eur Urol. 2009;55(5):997-1009.

Watts EL, et al. Low Free Testosterone and Prostate Cancer Risk: A Collaborative Analysis of 20 Prospective Studies. Eur Urol. 2018;74(5):585-594.

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