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Introduction and Objectives: In active surveillance (AS) for prostate cancer, we examine if having an externally performed diagnostic biopsy, compared to an in-house biopsy, predicts reclassification on the 2nd, otherwise known as the confirmatory, biopsy (B2).
Methods: We identified patients on AS from the database of our tertiary care referral centre (1997-2012) with PSA <20, Gleason sum (GS) 6, stage T1c, ≤ 3 positive cores (PCore) for cancer, <50% of single core involved, age ≤75y years and a repeat biopsy within 48 months after the initial biopsy. Patients were dichotomized on the basis of where their diagnostic biopsy (B1) was performed to internal (in-house) or external. All externally taken biopsies were reported externally. For all patients, B2 was performed internally. Comparison of the internal and external groups, examining both B1 and B2, were made using the MannWhitney-U and chi-squared tests. Logistical regression was used to assess if having the B1 performed externally was a predictor of reclassification at B2. Results: A total of 649 patients were included, divided into external (n=138) and internal biopsy groups (n=511). At baseline, patients with externally taken biopsies had more HGPIN (p=0.01) and ASAP (p=0.001) diagnosed, and less identification of TRUS nodules (p=0.001). The total number of cores taken at B1 was not statistically different between internal and external biopsy groups (p=0.07), however the internal group tended to have more cores taken. At B2, patients with external B1, compared to internal, had increases in all 3 pathological reclassification criteria: GS≥7 (24.6% versus 11.6%, p=0.001), PCore >3 (23% versus 11.7%, p=0.001) and highest % core involved >50% (18.5% versus 8.3%, p=0.006). They were also more likely to have a TRUS nodule seen on B2 (45.5% versus 32.5%, p=0.003). Predictors of reclassification at B2 are shown in Table 1.

Grade re-classification
external biopsy OR 2.86 (1.375-5.88), p=0.001
age OR 1.09 (1.665.08), p=0.001
PSA density OR 2.91 (1.041.15), p=0.001
maximum % core
involvement OR 1.05 (1.011.09) for every unit increase, p=0.009

Volume re-classification
external biopsy OR 2.08 (1.094.0), p=0.03
PSA density OR 2.15 (1.333.47), p=0.002


Conclusion: At our institution, patients who had their initial diagnostic prostate biopsy performed externally are more likely to have adverse pathological features and reclassify on internal re-biopsy.
Given these findings, this group of patients could be prioritized for earlier confirmatory biopsy.