When serial prostate biopsy is recommended: most cancers detected are clinically insignificant

Study Type - Disagnostic (exploratory cohort) Level of Evidence 2b. What's known on the subject? and What does the study add? Many patients undergo serial biopsy with a low rate of detection of prostate cancer, and the rate of detection declines as more biopsies are pursued. Furthermore, the clinical significance of detected cancer appears to decline as well. It is important to follow all possible methods to detect cancer; however, there should be a parallel consideration for the clinical value for detection of these tumours with low malignant potential. The present study investigated in detail the total rate of cancer detection in serial biopsy and how many of these were deemed clinically insignificant. Moreover, it addressed the impact of detecting premalignant lesions on further detection of cancer in serial biopsy.

Many patients pursue serial prostate biopsies after two consecutive negative biopsy sessions. The objective of this study is to determine the indications of serial prostate biopsy and to compare outcomes, including the risk of detecting clinically insignificant cancer using different biopsy protocols in this highly selected population.

• Most cases of prostate cancer are detected on initial or one repeat biopsy, but persistent suspicion of prostate cancer occasionally leads to serial biopsy, which we define as more than two biopsy sessions. We recently showed that transrectal saturation biopsy (sPBx) significantly increases cancer detection when compared with extended schemes (ePBx) in the initial repeat biopsy (second overall biopsy) population, and that most cases identified are clinically significant. • In the past decade, 479 men underwent 749 repeat prostate biopsies after two prior negative biopsy sessions. • The ePBx group included 347 biopsies with 10-14 cores. • The sPBx group included 402 biopsies with >20 cores. • We analysed overall cancer detection and risk of detecting clinically significant vs insignificant tumours.

Prostate cancer was detected in 15.9% of 749 serial biopsies, representing a cumulative prostate cancer detection rate of 24.8% (119/479 patients). • The sPBx group had a significantly higher detection rate per biopsy session (18.6% vs 12.7%, P= 0.026). • Nevertheless, most positive biopsies 75/119 (63%) revealed clinically insignificant cancer, including 74.6% of cancers detected by sPBx.

In men with two prior negative prostate biopsies, prostate cancer detection remains low regardless of clinical indication or transrectal biopsy protocol; most cancers identified are clinically insignificant, suggesting the threshold to repeat biopsy after more than one negative session should be very high.