Molecular testing for prostate cancer

Molecular diagnostics of prostate cancer is a set of methods that study hereditary and acquired changes in deoxyribonucleic acid, ribonucleic acid, and tumor protein signals. In modern urology and oncology, it is needed not to replace classical diagnostics, but rather to more accurately stratify risk, select patients for biopsy, select targeted therapy, immune therapy, and assess familial cancer risk. [1]

The key difference is that some tests evaluate inherited changes present in all cells of the body, while others evaluate changes that have arisen within the tumor itself. The former involves germline, or hereditary, testing using blood or saliva. The latter involves somatic, or tumor-specific, testing using biopsy tissue, surgical specimens, or circulating tumor deoxyribonucleic acid in the blood. [2]

It's important to understand that molecular diagnostics are not the same as simply measuring prostate-specific antigen (PSA). PSA remains an important early detection tool, but it does not indicate whether a specific tumor has a DNA repair defect, microsatellite instability, or a hereditary BRCA2 mutation. These characteristics can directly impact treatment and prognosis today. [3]

It's important to emphasize that pre-biopsy molecular testing and post-biopsy molecular testing are different tools. Pre-biopsy testing primarily involves blood and urine tests, which help reduce the number of unnecessary invasive procedures. Once the diagnosis is confirmed, tissue pathology, sequencing, and testing for genetic alterations that may be clinically significant take center stage. [4]

The modern approach is built around a simple idea: not every new biomarker is equally useful. Some tests are already integrated into clinical guidelines and can change treatment, while others only clarify the likelihood of clinically significant cancer, and some remain research-based. Therefore, a good article on the topic should not simply list the names of tests, but clearly categorize them according to their clinical purpose. [5]

Table 1. What is included in modern molecular diagnostics of prostate cancer

Direction	Material	The main task	Clinical status
Germinal, that is, hereditary, testing	Blood or saliva	Identification of inherited mutations and familial risk	Clinically significant in some patients
Somatic, i.e. tumor, testing	Tumor tissue	Search for changes that affect treatment	Particularly important in metastatic disease
Liquid biopsy	Blood	Search for tumor changes without repeat invasive biopsy	Useful in some situations, but not universal.
Blood markers before biopsy	Blood	Reducing the number of unnecessary biopsies	Auxiliary tool
Urine markers before biopsy	Urine	Clarification of the risk of clinically significant cancer	An auxiliary tool, part of the research tests

Sources for the table: European Urological Association, American Society of Clinical Oncology, and the US National Cancer Institute. [6]

Hereditary predisposition and germline testing

Prostate cancer is a tumor with a strong hereditary component. The US National Cancer Institute indicates that up to 60% of the risk of prostate cancer is due to hereditary factors, and familial clustering of the disease is common. This does not mean that the disease is entirely "genetic" in most patients, but it does mean that family history is indeed significant and should influence screening and early detection. [7]

Family history is not a mere formality. According to the US National Cancer Institute, having a father or brother with prostate cancer increases the risk, with the risk being higher if the relative developed the disease before age 65, and even higher if two or more first-degree relatives are affected. This link extends beyond prostate cancer: a family history of breast and ovarian cancer also increases the likelihood of developing the disease, reflecting the contribution of DNA repair genes, primarily BRCA2. [8]

Among clinically important genes, BRCA2 occupies a special place. The US National Cancer Institute emphasizes that tumors in carriers of pathogenic BRCA variants are more likely to behave aggressively, and this association is stronger for BRCA2. BRCA2 carriers are more likely to have higher Gleason scores, higher stage disease, and worse tumor-specific and overall survival compared to non-carriers. [9]

In addition to BRCA1 and BRCA2, ATM, PALB2, CHEK2, HOXB13, and mismatch repair genes associated with Lynch syndrome, including MLH1, MSH2, MSH6, and PMS2, are of clinical significance. The US National Cancer Institute specifically notes that HOXB13 was the first gene reliably linked to hereditary prostate cancer, and pathogenic variants in mismatch repair genes increase the risk of the disease and link a proportion of prostate cancer cases to Lynch syndrome. [10]

The European Association of Urology recommends considering germline testing in men with multiple cases of clinically significant prostate cancer in their family before age 60, in the presence of a relative who has died from prostate cancer, in the presence of a family history of high-risk germline mutations or multiple tumors in one family line, and in patients who have already been found to have a BRCA mutation in a somatic test. Genetic counseling is required before and after such testing. [11]

Table 2. Major hereditary genes in prostate cancer

A gene or group of genes	Clinical significance
BRCA2	Most compelling association with risk, aggression, and treatment impact
BRCA1	Significant for hereditary risk, but the impact is usually weaker than that of BRCA2
ATM	It is included in the testing panel and is important for some decisions in metastatic disease.
PALB2	Associated with deoxyribonucleic acid repair pathways
CHEK2	Used in multigene panels in some patients
HOXB13	Classic gene for hereditary prostate cancer, especially in early onset and familial cases
MLH1, MSH2, MSH6, PMS2	Lynch syndrome genes important for detection of mismatch repair defect

Sources for table: US National Cancer Institute and current guidelines for genetic testing. [12]

Table 3. When to consider germline testing

Situation	Practical conclusion
Metastatic prostate cancer in a candidate for targeted therapy	Testing should definitely be considered.
A BRCA mutation was found in the tumor.	It needs to be checked to see if it is hereditary.
Several cases of prostate cancer in the family before age 60	The case for testing
Death of a relative from prostate cancer	The case for testing
Family history of Lynch syndrome, breast, ovarian, and pancreatic cancer	Requires a more careful assessment of hereditary risk
Family history of high-risk mutations	Direct indication for testing discussion

Sources for the table: European Urological Association and US National Cancer Institute. [13]

Somatic tumor testing, tissue and liquid biopsy

Somatic testing evaluates molecular changes that have already arisen within the tumor. This is not a family analysis, but rather a study of the cancer itself. Its goal is to understand whether the tumor has defects in DNA repair, microsatellite instability, mismatch repair deficiency, and other changes that may predict sensitivity to specific treatments. [14]

In 2025, the American Society of Clinical Oncology formulated one of its clearest contemporary positions: patients with metastatic prostate cancer should undergo both germline and somatic DNA sequencing using panel methods. These tests are needed not "for the sake of curiosity," but because they can open access to poly(ADP-ribose) polymerase inhibitors and influence family testing of relatives. [15]

The European Association of Urology also strongly recommends offering patients with metastatic castration-resistant prostate cancer somatic and/or germline molecular testing, as well as testing for mismatch repair deficiency or microsatellite instability. This is no longer an optional textbook item, but part of modern standard oncological practice for advanced disease. [16]

Tumor analysis can be performed using either primary prostate tissue or metastatic lesions. Each source has limitations. Archival material is easier to obtain, but it may be less representative of the tumor's molecular composition at a late stage of treatment. Metastatic biopsy better reveals the current biology of the disease, but is invasive and not always technically feasible. This is why the role of liquid biopsy is increasingly being discussed in practice. [17]

The American Society of Clinical Oncology emphasizes that if there is a significant change in clinical status after a previously negative or non-informative result, it is reasonable to consider repeat testing, using either a metastatic biopsy or circulating tumor DNA as the material. However, the authors of the guidelines themselves note that data on the best tissue type and optimal repeat testing strategy are still limited. This is an important limitation that should not be hidden from the reader. [18]

Table 4. Tissue and liquid biopsy for molecular testing

Approach	Advantages	Restrictions
Primary prostate tissue	Available in many patients, it allows for comparison of morphology and genetics	May not reflect late tumor evolution
Metastatic biopsy	Better shows the actual biology of the disease	Invasive, not always feasible
Circulating tumor deoxyribonucleic acid	Less invasive, convenient for repeat testing	Doesn't always provide a sufficient signal; the optimal strategy is still being refined.

Sources for table: American Society of Clinical Oncology and European Association of Urology.[19]

Table 5. What somatic changes are most important in the clinic?

Change	Why is it important?
BRCA1 and BRCA2	May determine sensitivity to poly(ADP-ribose) polymerase inhibitors
ATM and PALB2	They are part of the spectrum of genes involved in deoxyribonucleic acid repair and are taken into account during profiling.
Mismatch repair deficiency	May indicate sensitivity to immune therapy
Microsatellite instability	A key predictor of tissue-independent immune therapy
High tumor mutational load	Sometimes taken into account in the tissue-independent approach, but the role is narrower

Sources for table: European Association of Urology, American Society of Clinical Oncology, and US Food and Drug Administration.[20]

Molecular markers before biopsy and in early detection

Before diagnosis, molecular tests serve a completely different purpose: they help determine who truly needs a prostate biopsy and who can avoid it. The European Association of Urology writes that urinary, serum, and tissue markers have been proposed to improve detection and risk stratification, potentially reducing the number of unnecessary biopsies, but further research is needed to confirm their effectiveness. This is a very balanced position: benefits are possible, but not absolute or universal. [21]

Among blood tests, the most well-known are the Prostate Health Index and 4Kscore. The European Association of Urology states that both tests are designed to reduce the number of unnecessary biopsies in men with elevated prostate-specific antigen. In prospective multicenter studies, they were superior to the free prostate-specific antigen/total prostate-specific antigen ratio in detecting cancer and better predicted clinically significant cancer in men with prostate-specific antigen levels of 2–10 nanograms per milliliter. [22]

IsoPSA, Stockholm3, and Proclarix also belong to this group. Stockholm3 is interesting because it combines clinical data, protein blood markers, and polygenic risk. When combined with magnetic resonance imaging, it can reduce the proportion of clinically insignificant tumors and potentially reduce the number of magnetic resonance imaging studies needed for screening. Proclarix is most often discussed in situations with uncertain magnetic resonance imaging. However, these tools remain purely probabilistic, not a standalone replacement for biopsy. [23]

Urinary tests include PCA3, SelectMDx, MyProstateScore, and ExoDx. The European Association of Urology notes that the clinical utility of the commercial PCA3 test for biopsy decision-making remains uncertain, although combination with magnetic resonance imaging may improve risk stratification. SelectMDx has been shown to reduce biopsy rates, but its added value in the era of pre-biopsy magnetic resonance imaging remains unclear. ExoDx and MiPS are currently explicitly labeled investigational in guidelines. [24]

The practical conclusion is this: additional molecular testing before biopsy is appropriate primarily as part of a multi-step algorithm. In asymptomatic men with prostate-specific antigen levels of 3-20 nanograms per milliliter and a normal digital rectal examination, the European Association of Urology recommends using prostate magnetic resonance imaging as a strong tool for deciding whether to proceed with a biopsy, and risk calculators and additional serum or urinary markers as a weak, i.e., auxiliary, option. This is more important than any test marketing description. [25]

Table 6. Most discussed pre-biopsy molecular tests

Test	Material	What helps to evaluate	Commentary on current recommendations
Prostate Health Index	Blood	Probability of clinically significant cancer	Useful for reducing unnecessary biopsies
4Kscore	Blood	Risk of clinically significant cancer	Useful as an auxiliary tool
IsoPSA	Blood	Probability of high-grade tumor	Promising, but not a mainstream standard
Stockholm3	Blood	Individualized risk based on clinical and genetic factors	Particularly interesting in early detection algorithms
Proclarix	Blood	Probability of clinically significant cancer	May be useful when magnetic resonance imaging is unclear.
PCA3	Urine	Risk of having a tumor	The clinical utility for biopsy decisions remains uncertain.
SelectMDx	Urine	Risk of cancer and high-risk cancer	The added value in the early MRI era remains unclear
MyProstateScore	Urine and serum data	Improving risk prediction	A promising but not basic standard
ExoDx	Urine	High-grade cancer probability	In the manual it is classified as research

Sources for the table: European Association of Urology. [26]

How molecular findings are changing treatment

The most clinically mature area of molecular diagnostics for prostate cancer is patient selection for poly(ADP-ribose) polymerase inhibitors. The European Association of Urology emphasizes that in metastatic castration-resistant prostate cancer, combinations with poly(ADP-ribose) polymerase inhibitors provide benefits primarily in tumors with defects in deoxyribonucleic acid repair, most significantly in carriers of BRCA1 and BRCA2 mutations. No separate recommendation is made for tumors without such defects. [27]

This logic is already enshrined in regulation. The US Food and Drug Administration indicates that olaparib is indicated for metastatic castration-resistant prostate cancer with mutations in the genes of homologous recombination repair of deoxyribonucleic acid after progression on previous therapy, talazoparib in combination with enzalutamide is indicated for metastatic castration-resistant prostate cancer with defects of homologous recombination repair, and rucaparib received full approval since December 2025 for BRCA-associated metastatic castration-resistant prostate cancer after therapy directed at the androgen receptor. [28]

The importance of specific genes varies. The US National Cancer Institute, in a treatment review, emphasizes that the benefit of olaparib was most convincingly demonstrated in the BRCA1, BRCA2, and ATM cohort, while the benefit in a broader group of other genes was less clear. For talazoparib and enzalutamide, the strongest effect was also described in tumors with BRCA alterations. This means that the formulation "any mutation in the repair system is present" is too crude for clinical reality: the biomarker should be interpreted based on the gene, stage, and line of treatment. [29]

The second major therapeutic line is associated with mismatch repair deficiency and microsatellite instability. The European Association of Urology recommends screening for these alterations in patients with metastatic castration-resistant prostate cancer, and the US Food and Drug Administration confirms tissue-independent approval of pembrolizumab for unresectable or metastatic tumors with high microsatellite instability or mismatch repair deficiency after prior treatment in the absence of satisfactory alternatives. Pembrolizumab also has tissue-independent approval for tumors with a high mutational burden, but this situation is less common in prostate cancer and is usually discussed in a specialized context. [30]

Finally, a molecular result changes not only the treatment regimen but also the patient and family's path. A positive germline result triggers cascade testing of relatives, clarification of the risk of other tumors, and earlier surveillance programs. The European Association of Urology already recommends early, individualized detection in men at increased risk, and for BRCA2 carriers, discussion of early prostate-specific antigen testing from age 40. Thus, molecular diagnostics for prostate cancer has long since moved beyond the scope of "stage 4 cancer." [31]

Table 7. How molecular findings may change treatment

Find	Potential clinical significance
BRCA1 or BRCA2	Reasons to consider poly(ADP-ribose) polymerase inhibitors at the appropriate stage and line of treatment
ATM and some other repair genes	Requires more nuanced interpretation than BRCA
Mismatch repair deficiency	Reasons to discuss immune therapy
High microsatellite instability	Reasons to discuss tissue-independent immune therapy
High tumor mutational load	An additional rare scenario for a tissue-independent approach
Germline mutation	Affects both treatment and genetic counseling for the family

Sources for table: European Urological Association, US National Cancer Institute, and US Food and Drug Administration. [32]

Limitations, errors and correct interpretation

The first common mistake is to assume that any modern molecular test automatically improves diagnosis. In reality, this is not the case. For some men with localized disease, extensive panels do not change the approach, and in early detection, even good markers remain merely an adjunct to clinical assessment, prostate-specific antigen (PSA), digital rectal examination (DRE), magnetic resonance imaging (MRI), and biopsy. The European Association of Urology explicitly emphasizes that diagnosis is usually confirmed histologically. [33]

The second mistake is to interpret a negative result as a definitive absence of clinically significant changes. The American Society of Clinical Oncology writes that repeat testing should be considered for previously negative or uninformative results, especially if there is a significant change in clinical status. This means that the molecular profile is not a "one-and-done" picture: it depends on time, material, and the biology of the progressing tumor. [34]

The third problem is an overreliance on markers with prognostic but not predictive value. The American Society of Clinical Oncology specifically warns that findings that have only prognostic value and do not predict treatment response should not be used to select therapy outside of clinical trials. Otherwise, patients receive the appearance of personalized medicine without any real evidence-based support. [35]

The fourth limitation concerns the quality of the material. The European Association of Urology points out that pathological processing of biopsy cores, section depth, and, where necessary, immunohistochemical staining are essential for accurate morphological diagnosis. This principle is no less important for molecular diagnostics: poor tissue quality, low tumor cellularity, and old archival material can limit the informativeness of the analysis, even if the test itself is technologically advanced. [36]

The 5th principle is that interpretation should be multidisciplinary. The European Association of Urology recommends managing patients with metastatic castration-resistant prostate cancer as part of a multidisciplinary team, and that genetic counseling is mandatory for germline testing. In practice, this means that a molecular result is meaningful only in conjunction with stage, morphology, prostate-specific antigen dynamics, imaging data, previous treatment, and family history. [37]

Table 8. Common errors in the interpretation of molecular tests

Error	Why this is incorrect
Consider any molecular test as a replacement for a biopsy	The diagnosis of prostate cancer usually requires histological confirmation.
Assess the pre-biopsy test as an independent diagnosis	These tests only clarify the likelihood of clinically significant cancer.
Consider a negative result final	In case of progression and uninformative material, repeat testing may be necessary.
Choose treatment based on prognostic rather than predictive markers	This does not comply with modern recommendations.
Do not refer the patient for genetic counseling	In case of germinal findings, this is an important part of the care
Ignore family history	You may be missing a hereditary syndrome and important recommendations for relatives

Sources for table: European Association of Urology and American Society of Clinical Oncology. [38]

FAQ

What is meant by molecular diagnostics for prostate cancer today?
It's not a single test, but a group of methods: genetic testing, tumor tissue testing, liquid biopsy, and molecular markers in the blood and urine, which help assess the risk of clinically significant cancer before biopsy. [39]

Can prostate cancer be diagnosed solely by molecular testing?
No. Current guidelines emphasize that the diagnosis is usually confirmed histologically, that is, by biopsy or surgical specimen. Additional markers merely help more accurately determine the path to biopsy or treatment. [40]

Who particularly benefits from germline, or hereditary, testing? This applies
primarily to men with metastatic disease, a family history of high-risk mutations, multiple cases of prostate cancer in the family at a young age, and patients whose tumors already carry a BRCA mutation. [41]

Which inherited genes are most important?
In practice, the most commonly discussed genes are BRCA2, BRCA1, ATM, PALB2, CHEK2, HOXB13, and the mismatch repair system genes associated with Lynch syndrome. Among these, BRCA2 has a particularly strong association with the aggressive course of the disease and with treatment decisions. [42]

Do all patients need broad molecular panels?
No. The most compelling indications are for patients with metastatic prostate cancer and for men with a strong hereditary risk. Broad profiling is not a mandatory standard for all patients with localized disease. [43]

What if the tissue for analysis is old or insufficient?
In such situations, a repeat metastasis biopsy or a liquid biopsy based on circulating tumor deoxyribonucleic acid may be considered. Current guidelines allow this approach, especially if the previous result was negative or uninformative and the clinical situation has changed. [44]

What benefit do pre-biopsy blood and urine tests provide?
They help reduce the number of unnecessary biopsies and better identify patients at risk for clinically significant cancer. However, they do not replace magnetic resonance imaging (MRI) or preclude biopsy if the likelihood of a significant tumor remains high. [45]

What is the most important test before a biopsy?
There is no single, universal test. The Prostate Health Index, 4Kscore, Stockholm3, and a number of urine tests can be useful, but the European Association of Urology considers them to be adjunctive tools, while prostate magnetic resonance imaging has a stronger recommendation for deciding whether to perform a biopsy. [46]

Why are BRCA and microsatellite instability so important?
Because these findings are directly linked to specific treatment options. BRCA and some other DNA repair disorders help select patients for poly(ADP-ribose) polymerase inhibitors, while high microsatellite instability or mismatch repair deficiency help select patients for the immune therapy pembrolizumab. [47]

Does a germline result change anything for the patient's relatives?
Yes. A positive germline result can lead to cascade testing of relatives and earlier monitoring of risk carriers. This is one of the reasons why genetic counseling is a mandatory part of proper genetic testing. [48]

Conclusion

Modern molecular diagnostics of prostate cancer is no longer a narrow laboratory exotica, but an important part of personalized patient care. At an early stage, it helps more accurately select men for biopsy, and when