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Prostate Cancer Biomarker Testing
Precision Management of Prostate Cancer With Biomarker Testing: An APP Perspective

Released: June 19, 2026

Brenda Martone
Brenda Martone, MSN, ANP-BC, AOCNP
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Key Takeaways
  • In metastatic prostate cancer, both germline and somatic testing can identify actionable findings; germline results also carry family-risk and genetic counseling implications.
  • HRR alterations occur in approximately 20% to 30% of prostate cancers, whereas dMMR/MSI-H and TMB-high status are less common but may open treatment options for selected patients.
  • APPs can reduce delays by discussing testing early, tracking tissue and liquid biopsy results, clarifying variants of uncertain significance, and helping patients understand PSMA PET and biomarker-directed therapies.

In this ClinicalThought commentary, Brenda Martone, MSN, ANP-BC, AOCNP, discusses the practical role of biomarker testing in prostate cancer, including when germline and somatic testing should be considered, how to interpret key biomarkers, and how results may inform treatment planning. Emerging clinical trial data, common testing challenges, and workflow strategies that can help advanced practice providers (APPs) integrate biomarker testing into longitudinal patient care are also reviewed.

Why Biomarker Testing Matters in Prostate Cancer
Prostate cancer remains one of the most common cancers affecting men in the United States. The American Cancer Society estimates 333,830 new cases and 36,320 deaths from prostate cancer in 2026, and approximately 1 in 8 men will be diagnosed with prostate cancer during their lifetime.

For APPs, the key question is not simply whether a biomarker is present but rather when testing should occur, when results should be available, and how those results should be communicated to patients. Biomarker testing can identify patients with prostate cancer who may be eligible for targeted therapies. For example, PARP inhibitors may benefit patients with selected DNA damage repair alterations, immune checkpoint inhibitors may be appropriate for selected microsatellite instability–high (MSI-H)/mismatch repair deficient (dMMR) or tumor mutational burden (TMB)–high tumors, and lutetium Lu 177 vipivotide tetraxetan may be an option for selected patients who have been treated with androgen receptor pathway inhibitor therapy and are considered appropriate candidates to delay taxane-based chemotherapy or who already have received prior taxane-based chemotherapy and have PSMA-positive metastatic castration-resistant prostate cancer (mCRPC).

Biomarker testing is as much a workflow issue as a molecular one. When biomarker testing is delayed until a patient is experiencing rapid disease progression, test turnaround times can delay clinical decision-making. By discussing and initiating testing earlier, APPs can help ensure that results are available when treatment selection, clinical trial referral, genetic counseling, or other time-sensitive care decisions become relevant.

Germline and Somatic Testing: Understanding Their Distinct Roles
A helpful way to explain testing to patients is that germline testing evaluates inherited variants present in normal cells, whereas somatic testing evaluates tumor-associated alterations. Germline testing may affect treatment planning, but it also raises implications for relatives, cascade testing, cancer risk counseling, and referral to a genetic counselor. Somatic testing can help identify tumor findings that may guide therapy and may be repeated at progression when new tissue or liquid biopsy information could change treatment options.

Current guideline-based approaches support offering both germline and somatic genetic testing to patients with metastatic prostate cancer. The American Society of Clinical Oncology (ASCO) 2025 guidelines specifically address germline and somatic genomic testing for metastatic prostate cancer and reinforce the importance of informed decision-making before germline testing.

Which Biomarkers Are Most Clinically Useful?
The prostate cancer biomarker resource highlights HRR alterations as a major actionable group, occurring in approximately 20% to 30% of prostate cancers. In a screened mCRPC population, selected tumor HRR (germline plus somatic) alterations included BRCA2 in 8.7%, ATM  in 5.9%, CDK12 in 6.3%, BRCA1 in 1.0%, CHEK2 in 1.2%, PPP2R2A in 1.0%, low-prevalence genes in 1.7%, and co-occurring genes in 2.1%, with no HRR gene alteration detected in approximately 72.1%. Germline prevalence ranges summarized in the resource include BRCA2 at 3.5% to 5.3%, BRCA1 at 0.9% to 1.3%, ATM at 0.3% to 2.0%, and PALB2 at 0.4% to 0.6%. 

Less common biomarkers can still inform treatment decisions. For instance dMMR/MSI-H, including alterations affecting MLH1, MSH2, MSH6, or PMS2, occurs in approximately 2.8% to 3.1% of prostate cancers, and TMB-high status occurs in approximately 1.5% to 4.7%, with higher rates reported in mCRPC. These findings are uncommon enough that many APPs will not see them often, but they may identify patients who could be considered for tissue-agnostic immunotherapy options when label criteria are met.

In contrast to the alterations described above that are evaluated through a sequencing panel, PSMA status is generally assessed with PSMA PET imaging. In common terms, PSMA is a protein expressed by many prostate cancer cells, particularly in advanced disease, and a PSMA-positive scan may support eligibility for PSMA-targeted radioligand therapy in the appropriate mCRPC setting.

Treatment Implications Without Overreading the Report
For patients with mCRPC and actionable DNA damage repair alterations, PARP inhibitor–based strategies have become part of the biomarker-directed treatment landscape. FDA-approved options include olaparib after progression on prior enzalutamide or abiraterone for selected deleterious or suspected deleterious germline or somatic HRR gene–mutated mCRPC; olaparib plus abiraterone and prednisone or prednisolone for BRCA-mutated mCRPC; niraparib plus abiraterone acetate and prednisone for BRCA-mutated mCRPC; talazoparib plus enzalutamide for HRR gene–mutated mCRPC; and rucaparib for BRCA-mutated mCRPC previously treated with androgen receptor-directed therapy.

Interpreting prostate cancer biomarker results requires attention to both the specific alteration and the clinical context. A BRCA1 or BRCA2 alteration does not create the same counseling issue if it is germline vs somatic, and not every HRR gene has the same level of evidence for every PARP inhibitor regimen. Variants of uncertain significance should not be treated as clearly actionable findings. When the report is unclear, confirm whether the alteration is pathogenic or likely pathogenic, whether it is germline or somatic, whether the patient meets the label criteria, and whether genetic counseling is needed.

For PSMA-positive mCRPC, the FDA expanded the lutetium Lu 177 vipivotide tetraxetan indication in March 2025 to include adults previously treated with an androgen receptor pathway inhibitor who are considered appropriate to delay taxane-based chemotherapy; patients should be selected using an approved PSMA PET product based on tumor PSMA expression. This is an example of why imaging-based biomarker assessment also belongs in APP conversations about sequencing and timing.

2026 Data Updates Regarding Biomarker Testing in Prostate Cancer
Recent data continue to move biomarker-directed strategies earlier in the prostate cancer disease course. Data from the phase III TALAPRO-3 trial presented at the 2026 ASCO Annual Meeting and concurrently published in the New England Journal of Medicine evaluated talazoparib plus enzalutamide vs placebo plus enzalutamide in men with HRR-altered metastatic castration-sensitive prostate cancer. At a median follow-up of approximately 37.6 months, talazoparib plus enzalutamide improved radiographic progression-free survival vs placebo plus enzalutamide, with a reported hazard ratio of 0.481; median radiographic progression-free survival was not reached vs 45.8 months. Although talazoparib plus enzalutamide is already approved by the FDA for HRR-mutated mCRPC, the TALAPRO-3 metastatic castration-sensitive prostate cancer regimen remains investigational unless and until regulatory status changes. This update is still highly relevant educationally because it reinforces why early HRR testing can shape future therapeutic planning and clinical trial conversations.

HER2-directed therapy is another evolving area. Trastuzumab deruxtecan (T-DXd) was granted accelerated approval for HER2-positive (IHC 3+) unresectable or metastatic solid tumors after prior systemic therapy and with no satisfactory alternatives, but its role in prostate cancer has not yet been established. A trial-in-progress abstract presented at the 2026 ASCO Genitourinary Cancers Symposium described the phase II CaRPET study of T-DXd in HER2-expressing mCRPC, supporting continued awareness without implying routine use for unselected prostate cancer.

Practical Barriers APPs Can Help Address
Collegial conversations have revealed several barriers that feel familiar across academic and community settings: identifying which patients need testing, waiting 10-14 days or longer for some results, knowing which test(s) to order, limited access to guidelines or resources, cost and reimbursement concerns, and uncertainty about how to explain results to patients. These barriers are best addressed not by expecting APPs to memorize every biomarker but by implementing a reproducible testing workflow that supports consistent ordering, interpretation, documentation, and follow-up. For instance:

  • Use guideline-based testing criteria to normalize biomarker testing conversations: In metastatic disease, biomarker testing should be offered regardless of age, race, health literacy, or social determinants of health.
  • Address affordability early without assuming cost is insurmountable: Many commercial insurance plans and Medicare may cover germline testing for appropriate patients, and laboratories may offer patient assistance programs. However, coverage and out-of-pocket costs vary, so financial navigation should begin early when needed.
  • Match the specimen strategy to the clinical question: Larger-volume, fresh formalin-fixed, paraffin-embedded tissue samples and nondecalcified or briefly decalcified bone specimens may improve testing success. Liquid biopsy can be useful, but low circulating tumor DNA shedding in patients with low-volume disease may lead to false-negative or inconclusive HRR results, and clonal hematopoiesis can generate apparent HRR alterations that raise false-positive concerns if not properly distinguished from tumor-derived mutations.
  • Escalate ambiguous or discordant results: When biomarker findings do not fit the clinical picture, APPs should involve pathology, molecular laboratory contacts, genetic counseling, and/or the treating oncologist.
  • Be transparent with patients about what testing can and cannot answer: Explain that a result may not change treatment today but can help the care team move faster if the cancer changes, or that a germline finding may require genetic counseling to clarify implications for family members.

A Practical Takeaway for the Clinic
For NPs and PAs, prostate cancer biomarker testing works best when treated as a longitudinal care process. Start the discussion early, distinguish germline and somatic implications, track pending results, clarify whether findings are actionable, and involve genetic counseling or pathology when needed. When APPs own these steps, biomarker testing becomes less of a late-stage scramble and more of a prepared pathway to individualized treatment planning.

Your Thoughts
What is the greatest barrier you encounter when integrating prostate cancer biomarker testing into practice: identifying who should be tested, obtaining an adequate specimen, navigating cost, interpreting germline vs somatic results, or explaining results to patients and their families?

Visit the program page, listen to an associated podcast, and download a resource on prostate cancer biomarkers to learn more about this topic.

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In the care of patients with prostate cancer, which biomarker testing step is most challenging in your practice?

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