Diagnostics of prostate cancer
Examinations for prostate cancer includes:
- Measurement of prostate specific antigen (PSA) in the serum
- Digital rectal exploration (DRE)
- Transrectal ultrasound (TRUS)
- MRI of prostate and pelvis. MRI may be performed before taking biopsies to achieve more targeted biopsies. The MRI images are then transferred to ultrasound before performing the biopsies. Prostate biopsies may also be performed as an ultrasound-guided transperineal /transrectal biopsy
- Skeletal scintigraphy
- X-ray thorax
- Additional image diagnostics
- Pelvic node staging
Prostate specific antigen (PSA)
The most frequent way of diagnosing prostate cancer is by an increase in PSA level in the serum. PSA is a glycoprotein secreted by the glandular cells in the prostate and mixes with semen to prevent coagulation. PSA is normally evident in small concentrations in the serum of men at a mature age. The PSA-level in the serum increases with diseases of the prostate such as benign prostate hyperplasia (BPH), prostatitis, and prostate cancer. PSA is not a cancer marker, however most malignant prostate cells also produce PSA which causes an increased “leakage” of PSA to the serum. This permits diagnosing cancer at an early stage.
|Upper limit of normal for PSA in Norway (3)
|< 50 years
|> 69 years
- In slight increases of PSA levels in the serum (< 10 ng/ml), BPH is more common than prostate cancer.
- In the area of 10-30 ng/ml, prostate cancer is the most likely.
- In a serum PSA > 100 ng/ml, there is almost always spreading from prostate cancer.
Digital rectal exploration (DRE)
DRE must be completed by the primary doctor if the symptoms or other findings cause suspicions of cancer. In this investigation, the size and consistency are evaluated and may provide valuable information.
The prostate is available for both transperineal and transrectal biopsy. Most common today is ultrasound guided transrectal biopsy. There is probably no qualitative impact whether the biopsy is taken transrectally or transperineally.
Before referral to a specialist for biopsy, the patient should be informed of the consequences of a malignant biopsy. In symptom-free patients over 70-75 years, it can be discussed whether curative treatment is appropriate.
Bone scintigraphy is a simple examination that require few resources. It has the status of a basic examination in intermediate and high risk prostate cancer cases. It is often supplemented with MRI of the bone, which is more sensitive for detecting spread to bone. MRI has also increased accuracy to detect possible spread to lymph nodes. PET-scans are currently not in general use, but are under development for prostate cancer work-up.
Pelvic lymph node staging of intermediary and high risk patients
Lymph node dissection in fossa obturatorius for diagnostic purposes has lost much of its relevance in recent years. New methods of diagnostic imaging such as MRI often provide enough information to determine whether the patient is a candidate for curative treatment.
At present, surgical removal of lymph nodes surrounding the prostate is done in the same session as radical prostatectomy with extended lymph node dissection. This may in some cases have a therapeutic effect.