Characteristics and clinical significance of prostate cancers missed by initial transrectal 12‐core biopsy

Study Type – Diagnostic (exploratory cohort) Level of Evidence 3a What's known on the subject? and What does the study add? Initial transrectal 12‐core biopsy has a small but definite risk of missing anterior significant prostate cancers irrespective of age, PSA, prostate volume and DRE findings. Our study yields valuable information for diagnosis and treatment decision of prostate cancer based on transrectal 12‐core biopsy. OBJECTIVE To characterize prostate cancers missed by initial transrectal 12‐core biopsy. PATIENTS AND METHODS Between 2002 and 2008, 715 men with prostate‐specific antigen levels in the range 2.5–20 ng/mL or abnormal digital rectal examination underwent three‐dimensional 26‐core prostate biopsy (i.e. a combination of transrectal 12‐core biopsy and transperineal 14‐core biopsy) on initial examination. Of the 257 patients diagnosed with cancer, 120 patients subsequently underwent radical prostatectomy. Cancers were grouped into TR12‐negative cancers (i.e. not detected through transrectal 12‐core biopsy but detected through transperineal 14‐core biopsy) and TR12‐positive (i.e. detected through transrectal 12‐core biopsy) cancers. Clinicopathological characteristics of the TR12‐negative and TR12‐positive cancers were evaluated. RESULTS TR12‐negative cancers comprised 21% of the three‐dimensional 26‐core biopsy‐detected cancers. The frequency of cancers with a biopsy Gleason score ≤6 and that of cancers with a biopsy primary Gleason grade ≤3 was higher in TR12‐negative cancers, at 58% and 83%, respectively, than in TR12‐positive cancers, at 25% ( P < 0.001) and 53% ( P < 0.001), respectively. The median number of positive cores in TR12‐negative cancers was two out of 26. TR12‐negative cancers were more frequently located anteriorly than posteriorly. The incidence of the TR12‐negative cancers was not associated significantly with any clinical variable. CONCLUSION Many of the cancers missed by initial transrectal 12‐core biopsy are probably low‐grade and low‐volume diseases, although initial transrectal 12‐core biopsy has a small but definite risk of missing anterior significant cancers.