Investigations

Investigations commonly used to determine the presence and/or extent of prostate cancers are

• prostate specific antigen (PSA) test
• digital rectal examination (DRE)
• transrectal ultrasound (TRUS)
• transrectal ultrasound (TRUS) guided biopsy
• imaging techniques (magnetic resonance imaging [MRI], computerised tomography [CT] scan, x-ray, bone scan) (1).

Possible investigations to to assess and stage the disease:

• MSU - for evidence of infection
• urea and electrolytes levels - to assess renal function
• liver function tests - raised liver alkaline phosphatase and gamma glutamyl transferase indicate hepatic secondaries
• bone alkaline phosphatase - raised if bony metastases
• IVU - to assess renal function and demonstrate any ureteric or bladder outflow obstruction
• plain X-rays of chest and lumbar spine - prostatic bony lesions are predominantly osteoblastic. The bone appears dense and coarse, and may be difficult to distinguish from the changes seen in Paget's disease of the bone
• technetium bone scan - indicated if plain films are negative or equivocal; demonstrates bony metastases
• CT scan or MRI - for enlarged lymph nodes, liver metastases

Notes:

• regarding use of prostate biopsy (2)
  • aim of prostate biopsy is to detect prostate cancers with the potential for causing harm rather than detecting each and every cancer. Men with clinically insignificant prostate cancers that are unlikely to cause symptoms or affect life expectancy may not benefit from knowing that they have the disease. Indeed, the detection of clinically insignificant prostate cancer should be regarded as an under-recognised adverse effect of biopsy
  • to help men decide whether to have a prostate biopsy, healthcare professionals should discuss with them their PSA level, digital rectal examination findings (including an estimate of prostate size) and comorbidities, together with their risk factors (including increasing age and black African or black Caribbean ethnicity) and any history of a previous negative prostate biopsy
    • serum PSA level alone should not automatically lead to a prostate biopsy
  • if the clinical suspicion of prostate cancer is high, because of a high PSA value and evidence of bone metastases (identified by a positive isotope bone scan or sclerotic metastases on plain radiographs), prostate biopsy for histological confirmation should not be performed, unless this is required as part of a clinical trial
    
    
• regarding use of imaging (2)
  • Magnetic resonance imaging and biopsy If the MRI or biopsy is negative
    • multiparametric MRI should be offered to people with prostate cancer who are going to be able to have radical treatment
      
      
    • multiparametric MRI should be offered as the first-line investigation for people with suspected clinically localised prostate cancer
      • report the results using a 5-point Likert scale
        
        
    • if Likert score is 3 or more then offer multiparametric MRI-influenced prostate biopsy
      
      
    • if Likert score is 1 or 2 then consider omitting a prostate biopsy for people whose multiparametric MRI - but only after discussing the risks and benefits with the person and reaching a shared decision
      • if a person opts to have a biopsy, systematic prostate biopsy should be offered
        
        
    • for people with a negative biopsy who have an MRI Likert score of 3 or more
      • discuss the possibility of significant disease in an MDT meeting with a view to repeating the prostate biopsy
        
        
    • for people who have a raised PSA and MRI Likert score of 1 or 2, and who have not had a prostate biopsy, repeat PSA test at 3 to 6 months and:
      
      
      • prostate biopsy should be offered if there is a strong suspicion of prostate cancer (for example, PSA density greater than 0.15 ng/ml/ml or PSA velocity greater than 0.75 ng/year, or strong family history), taking into account their life expectancy and comorbidities
      • discharge the person to primary care if the level of suspicion is low; advise PSA follow-up at 6 months and then every year, and set a PSA level for primary care at which to re-refer based on PSA density (0.15 ng/ml/ml) or velocity (0.75 ng/year)
        
        
    • for people who have a raised PSA, an MRI Likert score of 1 or 2 (or a contraindication to MRI), and negative biopsy, repeat PSA at 3 to 6 months and:
      
      
      • offer prostate biopsy if there is a strong suspicion of prostate cancer (for example, PSA density greater than 0.15 ng/ml/ml or PSA velocity greater than 0.75 ng/year, or strong family history), taking into account their life expectancy and comorbidities
      • discharge the person to primary care if the level of suspicion is low; advise PSA follow-up every 2 years, and set a PSA level for primary care at which to re-refer, based on PSA density (0.15 ng/ml/ml) or velocity (0.75 ng/year).

Notes:

• the information from the multiparametric MRI (mpMRI) scan taken before prostate biopsy is used to determine the best needle placement in ultrasound guided prostate biopsy. In rare cases, the biopsy may be MRI-guided (the needle is inserted within the MRI machine). In most cases, the biopsy that follows the mpMRI will be ultrasound-guided, but the specific area(s) targeted will be predetermined by the mpMRI data (2)

Reference:

• (1) Prostate Cancer Risk Management Programme Information for primary care; PSA testing in asymptomatic men. Evidence document. NHS Cancer Screening Programmes, 2010
• (2) NICE (May 2019).Prostate cancer Diagnosis and treatment