If you’ve been diagnosed with prostate cancer, you may wonder why two men with a similar PSA, Grade Group and cancer stage can respond differently to treatment. Part of the answer lies in the biology of the cancer itself. Molecular tests can examine changes in your tumour’s DNA or gene activity that are not visible on scans or through standard pathology alone.
These tests do not replace your PSA, imaging or biopsy results. Instead, in selected situations they can add information about how your cancer may behave or reveal biomarkers linked to particular treatments. Newer research is also exploring whether molecular features could help identify who is most likely to benefit from treatments such as chemotherapy.
What Could Molecular Testing Tell You About Your Prostate Cancer?
Molecular testing looks at your cancer’s DNA or gene activity to identify features that may not be visible from its size, stage or Gleason pattern. Germline testing can also check for genetic changes you were born with.
Your specialist can interpret molecular test results alongside your PSA, Grade Group, stage and imaging to build a more complete picture of your individual cancer. Depending on the type of test and your clinical situation, the results may provide information about risk or potentially relevant treatment options.
Why Are PSA, Grade Group and Stage Not Always Enough?
Your PSA, Grade Group and cancer stage remain essential for understanding your prostate cancer. However, men with similar results can still have very different outcomes because their cancers may behave differently at a biological level.
Molecular testing can reveal some of these biological differences, adding another layer of information to your PSA, Grade Group, stage and imaging rather than replacing them.
What Is the Difference Between Germline and Somatic Testing?
Germline testing usually uses DNA from a blood or saliva sample to look for genetic variants you were born with. Because these variants are inherited, a result may sometimes have implications for other members of your family.
Somatic testing looks instead at genetic changes that have developed within the cancer itself. If tumour testing identifies a pathogenic BRCA1 or BRCA2 alteration, your specialist may discuss germline testing to find out whether the change could be inherited. The meaning of the result should be clearly explained to you, particularly if it could also be relevant to your relatives.
Which Type of Molecular Test Answers Which Question?
| Test | What Is Analysed? | Main Question It Can Help Answer |
| Germline genetic testing | DNA from blood or saliva | Is there an inherited cancer-risk variant that may affect you or your relatives? |
| Somatic tumour sequencing | DNA/RNA from prostate cancer tissue | Does the cancer contain an acquired alteration that may affect treatment options? |
| Gene-expression/genomic classifier | Activity of multiple genes within the tumour | Is this cancer biologically at higher or lower risk of progression or recurrence? |
| ctDNA liquid biopsy | Tumour-derived DNA fragments in blood | Can tumour mutations be identified in advanced disease when tumour tissue is unavailable or inadequate? |
What Does Tumour Sequencing Look For?
Tumour sequencing analyses your cancer’s DNA to look for genetic changes that could affect how your prostate cancer behaves or responds to treatment. These may include changes in genes such as BRCA1 and BRCA2, as well as mismatch-repair and other abnormalities.
Finding a mutation does not automatically mean that there is a treatment designed for it. Your specialist needs to interpret the result in the context of your cancer, previous treatment and the therapies currently available to determine whether a particular finding is clinically useful.
What Is a Genomic Classifier?
A genomic classifier looks at the activity of multiple genes in your prostate cancer and combines the results into a risk score. Tests such as Decipher, Genomic Prostate Score and Prolaris can provide additional information about your risk of progression or recurrence.
A higher genomic score does not automatically mean that you need a particular treatment. These tests are mainly used to provide additional information about prognosis, and they are not routinely required for every man with prostate cancer. Their value is greatest when the result could genuinely help resolve an uncertain treatment or monitoring decision.
Does the Test Predict Your Risk or Which Treatment May Help?
A prognostic biomarker gives you information about how your cancer may behave, such as the likelihood of it progressing or returning. A predictive biomarker answers a different question: whether people with a particular test result appear more likely to benefit from a specific treatment.
That distinction matters when we talk about personalised treatment. A test that predicts risk can still be useful, but it is different from having evidence that the test can help select one treatment over another.
What Did the STAMPEDE Molecular Study Examine?
STAMPEDE is a major UK-led research programme that has tested different treatment approaches for men with high-risk and advanced prostate cancer. In a 2025 molecular analysis, researchers studied tumour samples from 1,523 participants, including 832 men with metastatic disease, and linked the molecular findings with long-term outcomes from the STAMPEDE trials.
The question was particularly important for personalised treatment: could the biology of an individual tumour help identify which men gain more benefit from treatments such as docetaxel?
Could Decipher Identify Who Benefits Most From Docetaxel?
The 2025 STAMPEDE molecular analysis found that, among patients with metastatic prostate cancer, the Decipher classifier was prognostic and also predicted differential survival benefit from adding docetaxel to androgen-deprivation therapy. Men with high scores appeared to have a greater survival benefit, while the benefit was much smaller in men with lower scores.
This raises the possibility that tumour biology could one day help specialists identify which men are most likely to gain enough benefit from docetaxel to justify its potential side effects. However, these findings should not yet be used as a stand-alone rule for deciding whether an individual patient should receive chemotherapy.
Evidence Note
The 2025 STAMPEDE molecular analysis included tumour molecular data from 1,523 participants, 832 of whom had metastatic prostate cancer. Decipher was prognostic in metastatic disease and showed a statistically significant interaction with docetaxel treatment, suggesting that tumour gene-expression patterns may help identify differences in chemotherapy benefit. However, this was a biomarker analysis of samples from existing randomised trials, so further validation is important before Decipher is used as a routine stand-alone test to decide who should receive docetaxel.
What Did STAMPEDE Show About PTEN?
PTEN helps control how cells grow, and losing its activity can make your prostate cancer more aggressive. STAMPEDE found that cancers with PTEN inactivation had poorer outcomes with hormone therapy alone but appeared to benefit more from docetaxel.
These findings suggest that tumour biology could eventually help specialists choose treatment more precisely. However, PTEN status remains investigational as a treatment-selection biomarker and should not currently be used as a stand-alone rule for deciding whether you should receive docetaxel.
Research Insight
Decipher and PTEN appeared to provide partly different information about response to chemotherapy. In the metastatic group, PTEN-inactive cancers showed greater sensitivity to docetaxel, and the interaction between PTEN status and docetaxel treatment was statistically significant.
These are important findings, but they come from a biomarker analysis using tumour samples collected through earlier randomised STAMPEDE trials. They should therefore be viewed as promising evidence rather than a routine rule that determines treatment for an individual patient.
Could Molecular Testing Also Personalise Abiraterone Treatment?
The STAMPEDE molecular analysis did not establish Decipher or PTEN as reliable tests for selecting who should receive abiraterone. In metastatic disease, patients benefited from abiraterone across both high- and lower-Decipher groups, and the difference in treatment effect between these groups was not statistically convincing.
PTEN status also did not significantly change the benefit seen with abiraterone. For now, molecular results such as Decipher and PTEN should therefore not be used alone to decide whether abiraterone is suitable for you.
Why Are BRCA1, BRCA2 and Other DNA-Repair Genes Important?
BRCA1 and BRCA2 help cells repair damaged DNA. Finding a pathogenic alteration in one of these genes can be particularly important because it may affect inherited-risk assessment and eligibility for some targeted treatments.
Some PARP-inhibitor treatments are specifically linked to BRCA mutations, while other NICE-recommended PARP-inhibitor combinations do not require a BRCA mutation. Your specialist will therefore consider the exact molecular finding, whether it is germline or somatic, your stage of disease, previous treatments and the current NICE recommendations before deciding which options may be appropriate for you.
Can Molecular Testing Identify Other Targetable Abnormalities?
Yes. Molecular testing can identify other abnormalities, including mismatch-repair deficiency (dMMR) or high microsatellite instability (MSI-H). These findings may be clinically relevant and can sometimes influence specialist discussions or eligibility for clinical research.
However, finding a potentially interesting molecular abnormality does not automatically mean that an approved treatment is available for prostate cancer. Your options depend on the specific finding, your stage of disease and current UK treatment approvals.
Can Genomic Tests Help With Localised Prostate Cancer?
Genomic classifiers can provide additional information about how aggressive a localised prostate cancer may be. In selected cases, this may be helpful when there is still uncertainty about options such as active surveillance or treatment after your PSA, MRI and biopsy findings have been considered.
They are not routinely required for every man with localised prostate cancer. Your PSA, Grade Group, MRI, biopsy findings and clinical stage remain central to treatment decisions.
Can Molecular Testing Help After Robotic Prostate Surgery?
In selected patients, genomic testing can add prognostic information after robotic prostate surgery, particularly when your specialist is trying to understand your risk of recurrence alongside the surgical pathology and PSA results.
- Recurrence Risk: Genomic tests may provide additional information about how likely your cancer is to return or spread.
- Pathology Support: Your molecular results can be considered alongside your Grade Group, stage and surgical margins.
- PSA Monitoring: Your postoperative PSA remains important and helps your specialist interpret your molecular results in context.
- Further Treatment: Molecular information may eventually help guide decisions about whether you could benefit from additional treatment.
Molecular testing does not replace your pathology or regular PSA monitoring after surgery. Your specialist will consider all of your results together when planning your follow-up and deciding whether further treatment may be appropriate.
Could a Blood Test Replace Tumour Tissue for Molecular Testing?
Sometimes. A liquid biopsy can analyse circulating tumour DNA, or ctDNA, in your blood and may provide molecular information when suitable tumour tissue is unavailable, particularly in advanced prostate cancer.
Whether this type of testing is appropriate or available will depend on your individual treatment pathway. It is also important to understand that very little tumour DNA may be circulating in the blood, so a result reported as ‘not detected’ does not always rule out a mutation.
Why Can the Same Prostate Cancer Change Molecularly Over Time?
Your prostate cancer can change as it grows and responds to treatment. This means its molecular profile at diagnosis may differ from the cancer that remains or spreads later.
If your cancer becomes resistant to treatment, repeat molecular testing can sometimes provide useful new information because the cancer may have evolved. Whether another test would be worthwhile depends on your disease stage, previous results, the samples available and whether the result could change your next treatment.
What Are the Limitations of Molecular Testing?
Molecular testing can give you useful information, but it does not always provide a clear answer. Your biopsy may not capture every tumour change, and older or limited tissue may also affect test accuracy.
Finding a genetic alteration does not automatically mean that a matching treatment is available or that it will work. The quality and amount of tumour tissue, access to testing, cost and results whose significance is uncertain can also limit how useful molecular testing is in practice.
Is Molecular Testing Already Part of Routine Prostate Cancer Care?
Yes, but only in selected situations. Molecular testing is increasingly relevant in advanced prostate cancer, particularly when the result could identify an inherited risk or influence treatment. However, it is not automatically offered to everyone diagnosed with prostate cancer.
Your specialist will consider your disease stage, previous treatment, family history and whether a test result is likely to change your care before recommending testing.
UK Guidance Note
In England, NHS genomic testing is targeted rather than routinely offered to every person with prostate cancer. Eligibility depends on the tests commissioned through the NHS genomic testing pathway and on whether the result is expected to influence clinical management or provide important information about inherited cancer risk.
European prostate cancer guidelines also support molecular testing in selected men with advanced disease, particularly where homologous-recombination repair or mismatch-repair abnormalities could be clinically relevant. These European recommendations should not be confused with NHS commissioning criteria, which determine access to specific tests in England.
What Should You Ask About Molecular Testing?
One of the most useful questions to ask is: “What decision could this test change for me?”
You can also ask whether the test looks at inherited DNA or the cancer itself, what a positive or negative result would mean, whether it could change your treatment and whether the result might have implications for your relatives. Knowing why the test is being offered can make the result much easier to understand when you receive it.
Myth vs Fact:
| Myth | Fact |
| All molecular tests tell your doctor which treatment will work. | Many genomic classifiers are mainly prognostic and estimate risk rather than predict response to a specific treatment. |
| A high Decipher score automatically means you need chemotherapy. | STAMPEDE found that high Decipher scores predicted greater docetaxel benefit in metastatic disease, but treatment still depends on your overall clinical situation. |
| STAMPEDE proved Decipher can select who should receive abiraterone. | No. Both high- and lower-Decipher groups benefited, and Decipher did not show a statistically convincing treatment interaction for abiraterone. |
| A BRCA2 mutation means every patient should receive a PARP inhibitor immediately. | PARP-inhibitor eligibility depends on disease stage, prior treatment, the specific alteration and current treatment approvals. |
| Somatic and germline testing are the same. | Somatic testing examines changes within the cancer; germline testing identifies inherited variants that may also matter to relatives. |
| A negative liquid biopsy rules out a tumour mutation. | Low ctDNA levels can produce false-negative results, particularly when tumour burden is low. |
| Everyone with localised prostate cancer needs a genomic classifier. | Current guidance recommends selective use when the result is likely to change management, not routine testing for everyone. |
Key Takeaways
- Molecular testing can analyse tumour DNA, RNA or gene expression, while germline testing identifies inherited variants that may also affect relatives.
- Some biomarkers are prognostic, meaning they estimate risk, while predictive biomarkers show whether treatment benefit differs according to the test result.
- The 2025 STAMPEDE molecular analysis found that high Decipher scores and PTEN inactivity were associated with differences in docetaxel benefit in metastatic disease, although these biomarkers are not yet stand-alone routine rules for selecting chemotherapy.
- The same STAMPEDE evidence did not establish Decipher or PTEN as reliable selectors of abiraterone benefit.
- BRCA1/2 and other DNA-repair alterations can influence targeted-treatment options in selected patients with advanced prostate cancer.
- Genomic classifiers such as Decipher can add prognostic information in localised or postoperative disease, but they are not routinely required for every patient.
- ctDNA can sometimes provide genomic information when tumour tissue is unavailable, but a negative blood result does not necessarily rule out a tumour mutation.
- Molecular results should always be interpreted alongside PSA, Grade Group, stage, imaging, pathology, previous treatments and your overall health.
Frequently Asked Questions
1. What Is Molecular Testing for Prostate Cancer?
Molecular testing looks at your cancer’s DNA or gene activity to identify features that may not be clear from your PSA, Grade Group or stage. It can provide additional information about how your cancer may behave or respond to treatment.
2. What Is the Difference Between Germline and Somatic Testing?
Germline testing looks for inherited genetic changes that you were born with, while somatic testing examines genetic changes within your tumour. Your doctor may recommend one or both depending on your cancer and treatment options.
3. Can Molecular Testing Help Personalise Your Prostate Cancer Treatment?
Potentially. Molecular testing can identify genetic or gene-expression features that may provide additional information about your risk or, in selected situations, influence treatment choices. However, not every molecular finding leads to a specific treatment.
4. What Is a Genomic Classifier?
A genomic classifier analyses the activity of multiple genes in your prostate cancer and produces a risk score. Tests such as Decipher, Prolaris and Genomic Prostate Score can provide additional information about your risk of progression or recurrence.
5. What Is the Difference Between a Prognostic and Predictive Test?
A prognostic test gives you information about how your cancer may behave, such as its risk of recurrence. A predictive test aims to show whether you are more likely to benefit from a particular treatment.
6. Can Molecular Testing Identify BRCA1 or BRCA2 Mutations?
Yes, depending on the type of test. Tumour testing can identify BRCA1 or BRCA2 alterations within the cancer, while germline testing can determine whether an alteration is inherited. Finding a pathogenic BRCA1 or BRCA2 alteration can affect inherited-risk assessment and eligibility for some PARP-inhibitor treatments, although current NICE recommendations differ between treatments.
7. Can Molecular Testing Be Used After Robotic Prostate Surgery?
In selected patients, genomic testing may provide additional prognostic information after robotic prostate surgery. Your doctor can consider these results alongside your pathology, PSA and other clinical findings.
8. Can a Blood Test Be Used Instead of Tumour Tissue?
Sometimes. A liquid biopsy can analyse ctDNA in your blood and look for genetic changes, particularly when you have advanced prostate cancer. However, a negative blood test does not always rule out a mutation if there is too little tumour DNA.
9. Can Your Prostate Cancer Change Its Molecular Profile Over Time?
Yes. Your cancer can change as it grows or responds to treatment, meaning its molecular features may differ later in the disease. Repeat testing may sometimes provide useful information when your cancer becomes resistant to previous treatments.
10. What Should You Ask Your Doctor About Molecular Testing?
Ask what the test is designed to tell you, whether it is germline or tumour-based, and how the result could affect your treatment. You should also ask whether the result is likely to change a clinical decision for you.
Final Thoughts: How Molecular Testing Could Shape Your Prostate Cancer Treatment
Molecular testing is adding another layer to how prostate cancer can be understood, but it is most useful when the result answers a specific clinical question. For some men, testing may identify a genetic alteration that influences treatment or inherited-risk assessment. For others, it may provide additional information about prognosis without immediately changing treatment.
Your PSA, imaging, biopsy or surgical pathology and overall health remain central to decision-making. If you have been diagnosed with prostate cancer and want to understand how your test results fit together, you can contact our team at Prostate Clinic London to discuss your individual situation with a specialist.
References:
- Grist, E., Dutey-Magni, P., Parry, M.A. et al. (2025) ‘Tumor transcriptome-wide expression classifiers predict treatment sensitivity in advanced prostate cancers’, Cell, 188(20), pp. 5717–5734.e10. Available at: https://pubmed.ncbi.nlm.nih.gov/40865526/
- NHS England (2026) National genomic test directory. Current 2026 editions include the National Genomic Test Directory for cancer and the rare and inherited disease eligibility criteria. Available at: https://www.england.nhs.uk/publication/national-genomic-test-directories/
- European Association of Urology (EAU) (2026) EAU Guidelines on Prostate Cancer. 2026 edition. Accessed: 11 September 2026. Available at: https://uroweb.org/guidelines/prostate-cancer
- National Institute for Health and Care Excellence (NICE) (2023) Olaparib for previously treated BRCA mutation-positive hormone-relapsed metastatic prostate cancer. Technology appraisal guidance TA887. Published 10 May 2023. Available at: https://www.nice.org.uk/guidance/ta887
- National Institute for Health and Care Excellence (NICE) (2024) Olaparib with abiraterone for untreated hormone-relapsed metastatic prostate cancer. Technology appraisal guidance TA951. Published 7 February 2024. Available at: https://www.nice.org.uk/guidance/ta951
- National Institute for Health and Care Excellence (NICE) (2026) Talazoparib with enzalutamide for untreated hormone-relapsed metastatic prostate cancer. Technology appraisal guidance TA1130. Published 11 February 2026. Available at: https://www.nice.org.uk/guidance/ta1130
- de Bono, J., Mateo, J., Fizazi, K., Saad, F., Shore, N., Sandhu, S., Chi, K.N., Sartor, O., Agarwal, N., Olmos, D. et al. (2020) ‘Olaparib for metastatic castration-resistant prostate cancer’, The New England Journal of Medicine, 382(22), pp. 2091–2102. Available at: https://pubmed.ncbi.nlm.nih.gov/32343890/