Chapter 20: Diagnostic investigations
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Related theory
As a man ages, the transition zone increases in size due to benign prostate enlargement (BPE) while the central zone atrophies and the peripheral zone remains the same. It is the peripheral zone, however, in which the majority of prostate cancers are found and therefore clinically this is the most important region to target during prostate biopsy.
Transrectal biopsy of the prostate is most commonly undertaken in an outpatient setting. Many thousands of prostate biopsies are undertaken every year throughout the UK. First described by Astraldi in 1937, it remains the gold standard investigation for diagnosing prostate cancer (Turner et al. [164]).
Prostate biopsy specimens
The number of specimens to be collected and the location will depend on the patient's clinical condition. The following should be considered when determining specimen collection:
- Ultrasound does not detect areas of prostate cancer with adequate reliability and therefore targeted prostate biopsies on the basis of ultrasound alone are unproductive. However, occasionally additional biopsies of abnormal areas identified on magnetic resonance imaging (MRI) can be useful (Heidenreich et al. [63], Siddiqui et al. [148]). On the first biopsy (baseline biopsy) the sample sites should be as far posterior and lateral in the peripheral zone as possible.
- When cancer is suspected a 12 core biopsy protocol should be observed (Heidenreich et al. [63]). However, if the patient has proven or strongly suspected advanced prostate cancer or is part of a clinical trial, limited cores should be taken (2–4 being optimal).
- The 12 core biopsy protocol is as follows (Figure 20.8):
- right apex lateral × 2
- right mid lateral × 2
- right base lateral × 2
- left apex lateral × 2
- left mid lateral × 2
- left base lateral × 2.
Figure 20.8 Prostate core biopsy.
