Biopsy follow-up in patients with isolated atypical small acinar proliferation (ASAP) in prostate biopsy

The incidence of prostate cancer (PCA) was evaluated in 155 patients with isolated Atypical Small Acinar Proliferation (ASAP) found on initial prostate biopsy, after a medium-term follow-up (40 months) with at least one re-biopsy. Clinical and histological data were analysed. Cancer was detected in 81 of 155 (52.3%). The cancer detection rate was 71.6%, 91.3%, 97.5%, 100% at the 1st re-biopsy, 2nd, 3rd, and 4th rebiopsy respectively. At the uni- and multivariate analyses, prostate volume (≤ 30 cc), transition zone volume (≤ 10 cc), small core length at the initial biopsy (≤ 10 mm) and few number of cores at initial biopsy (≤ 8) are predictive of cancer. Furthermore, tumour characteristics on the whole surgical specimens was assessed in 30 men: 13 of 30 (43 %) had clinically relevant cancer (volume > 0.5 ml or/and Gleason score ≥ 7, or pT3). Most of relevant cancers were detected in the distal apex, anterior gland and midline. These anatomical sites could be under-sampled at the initial biopsy using the transrectal approach. Our data suggest that follow-up biopsy is recommended in all cases of isolated ASAP detected after biopsy using endfire transrectal probe. The re-biopsy strategy should increase the number of cores (or a saturation biopsy), focusing on area of ASAP in the initial biopsy, but also including the under-sampled areas (anterior gland, distal apex and midline) to detect clinically relevant cancers.