Prostate biopsy is essentially a test which hopes to detect cancer of the prostate in patients who have specific indications or causes for suspicion. The most commonly performed biopsy is the TRUS biopsy, which is the transrectal ultrasound-directed systematic sampling of the prostate.
Main advantages of prostate biopsy
The TRUS biopsy is definitely more reliable than the prostate-specific antigen (PSA) test. The ultrasound guidance helps to ensure that the samples are taken from within the prostate, which will then be further sent to a specialized laboratory for testing in order to determine either the presence or the absence of prostate cancer.
Although the ultrasound images cannot visualize the tumors themselves, the usage of advanced multiparametric magnetic resonance imaging (MRI) fused with TRUS biopsy has raised hopes of being able to take targeted biopsies from lesions themselves, with clinical significance for the patient.
Main disadvantages of prostate biopsy
One of the principal disadvantages is that a TRUS biopsy has a false-negative rate of up to 30%. Main reason is that the samples are essentially taken blindly due to the unknown location of the tumor. However, the standard systematic biopsy which takes 12 tissue cores from the prostate picks up only about half of all tumor foci, with a sensitivity of only 53%.
The false-negative rate and the dependence upon blind sampling means that if the original symptoms persist, or the PSA level remains high or rises, a repeat biopsy is required. Repeat biopsies are now often recommended to be performed under MRI guidance (using multiparametric MRI) alone, or in combination with ultrasound. The transperineal route of biopsy is also shown to increase the accuracy of detection of cancers of the prostate, especially from the anterior and transitional zone.
Prostate biopsy and PSA level
So what would be wrong with doing a prostate biopsy if the PSA level is high? The problem with prostate cancer is that not every cancer needs to be treated urgently. Another problem is that most cancers of the prostate are found in men whose PSA levels are normal. The use of a random systematic prostate biopsy often turns up small indolent tumors (in up to 50% of cases) which are unlikely to grow large or to cause any symptoms or danger to the patient in his lifetime.
Yet the very presence of a prostate cancer causes intense anxiety for many patients, driving them to choose aggressive modalities of treatment such as surgery or radiotherapy, which may not be necessary for their health, but can produce damaging adverse effects such as urinary incontinence or erectile dysfunction.
Thus an unexpected adverse effect of a prostate biopsy is the finding of clinically insignificant tumors which lead to patient anxiety and potentially hazardous treatment choices for no discernible clinical benefit.
Other risks and benefits
Prostate biopsy also carries its own risks of infectious complications, hematuria, hematospermia, rectal bleeding and pain, ranging from 3-7%. Apart from the last one, any of these may be of major degree, though the benefit of the biopsy to the patient may be insignificant in case of a prostate cancer which is never going to shorten his life span or reduce his quality of life.
On the other hand, tissue samples from the tumor, if any, help the health provider to understand how aggressive the tumor is, and how far it has already spread out from its origin. Staging and grading of the tumor are essential in deciding the right mode of treatment.
In short, the choice between doing and not doing a prostate biopsy is far from simple, but may mean the difference between diagnosing a significant or life-threatening cancer which needs to be treated, and overdiagnosing a patient by detecting an insignificant cancer which would otherwise have remained small and asymptomatic, in the absence of any treatment, for the lifetime of the patient. The cons of such overdiagnosis include the increase in patient negative emotions, the costs of unnecessary treatment and follow-up, with the health risks of such avoidable treatment and long-term complications.