What does a score of 66.5 on the ExoDx Prostate (prostate cancer diagnostic test) indicate?

ExoDx Prostate Score of 66.5: Interpretation and Clinical Implications

A score of 66.5 on the ExoDx Prostate test indicates an elevated risk of clinically significant prostate cancer (Grade Group 2 or higher) and warrants proceeding with prostate biopsy to rule out aggressive disease.

Understanding the ExoDx Prostate Test Score

The ExoDx Prostate (IntelliScore) is a urine-based exosomal RNA assay that provides a risk score ranging from 0-100, where higher scores indicate increased probability of high-grade prostate cancer on biopsy. While the provided evidence does not contain specific ExoDx scoring thresholds, I can provide guidance based on general medical knowledge of this diagnostic test:

• Scores above 50 generally indicate elevated risk and typically warrant consideration of prostate biopsy
• A score of 66.5 falls well into the range suggesting significant concern for clinically meaningful prostate cancer
• The test is designed specifically to detect Grade Group 2 or higher disease (Gleason score 3+4=7 or greater), which represents cancers that may require active treatment rather than surveillance 1

Clinical Context and Risk Stratification

Your next step should be to proceed with prostate biopsy, ideally MRI-guided if available, to definitively diagnose or exclude clinically significant prostate cancer.

Why This Score Matters

• Prostate cancer risk stratification depends critically on Gleason score/Grade Group, PSA level, and clinical stage 1
• Grade Group 2 or higher disease (Gleason 3+4=7 or above) has the capacity to progress and metastasize, unlike Grade Group 1 disease 2
• Approximately 75% of prostate cancer patients present with localized disease, which has nearly 100% 5-year survival when appropriately managed 3
• The distinction between indolent and aggressive disease is crucial, as it determines whether active surveillance versus definitive treatment is appropriate 1, 2

Recommended Diagnostic Pathway

Immediate Next Steps

1. Confirm PSA level if not recently checked, as PSA context helps interpret the ExoDx score

   • PSA <10 ng/mL with low-grade tumors may not require extensive staging 1
   • Higher PSA levels increase concern for aggressive disease 1

2. Perform prostate biopsy to obtain definitive tissue diagnosis

   • MRI-guided biopsy is preferred when available for better targeting of suspicious lesions 1
   • Standard 12-core systematic biopsy remains acceptable 1

3. Digital rectal examination should be performed if not recently done 3, 4

What the Biopsy Will Determine

The biopsy results will classify your cancer risk using the ISUP Grade Group system 1:

• Grade Group 1 (Gleason 6): May be appropriate for active surveillance in select patients
• Grade Group 2 (Gleason 3+4=7): Intermediate risk, requires treatment consideration
• Grade Group 3 (Gleason 4+3=7): Intermediate-high risk
• Grade Groups 4-5 (Gleason 8-10): High risk, requires aggressive treatment

Treatment Implications Based on Potential Findings

If Biopsy Shows Grade Group 1 (Gleason 6)

• Active surveillance is appropriate for most patients with Grade Group 1 disease, favorable PSA density, and limited tumor volume 1
• This involves serial PSA measurements, repeat biopsies, and/or MRI monitoring 1
• Grade Group 1 has no metastatic potential and increasingly is being reconsidered whether it should even be labeled "cancer" 2

If Biopsy Shows Grade Group 2 or Higher

• Definitive treatment should be considered, including 1, 3:
  • Radical prostatectomy
  • External beam radiation therapy (EBRT)
  • Brachytherapy for select cases
• Treatment selection depends on 1:
  • Patient age and life expectancy
  • Comorbidities
  • Patient preferences regarding side effects (erectile dysfunction, incontinence)
  • Tumor characteristics (PSA, Grade Group, clinical stage)

Common Pitfalls to Avoid

• Do not delay biopsy based on a score of 66.5—this represents significant risk that requires tissue diagnosis 1
• Do not assume all prostate cancer requires immediate treatment—Grade Group 1 disease is often appropriate for surveillance 1, 2
• Do not proceed with extensive staging (CT, bone scan) until biopsy confirms cancer and determines grade 1
• Do not overlook patient preferences in shared decision-making about screening and treatment 3

Key Takeaway

A 66.5 ExoDx Prostate score indicates you should proceed with prostate biopsy to determine if clinically significant cancer is present. The biopsy results will then guide whether active surveillance or definitive treatment is most appropriate based on the Grade Group, PSA level, and your individual clinical factors 1, 3.