Implications of a diagnosis of atypical small acinar proliferation (ASAP) and high-grade prostatic intraepithelial neoplasia (HGPIN) on prostate biopsy: a 5-year follow-up study

Background In the era of active surveillance of low- and intermediate-risk prostatic cancer, a reconsideration of the implications of a biopsy report of ASAP and/or HGPIN may be timely. Aims We investigated the implications of a diagnosis of atypical small acinar proliferation (ASAP) and high-grade prostatic intraepithelial neoplasia (HGPIN) on prostate biopsy. Methods The rate of re-biopsy and the incidence of carcinoma on repeat biopsy for benign, HGPIN, and ASAP groups were compared. Mean PSA and PSA velocity was also compared between groups. Results There was an increased risk of developing prostate cancer in the following 5 years with a biopsy diagnosis of ASAP compared to benign (20% vs 5.9%, p = 0.009), and with a biopsy of HGPIN compared with benign (14.8% vs 5.9%, p = 0.005). The frequency of repeat biopsy following a diagnosis of ASAP (54.2%) vs. HGPIN (37%) was not significantly different ( p = 0.079). The risk of developing prostate cancer was highest following a biopsy with concomitant ASAP and HGPIN compared to benign (50% vs 5.9%, p < 0.001). There was no significant difference in PSA values between the 3 diagnostic groups at the time of initial biopsy ( p = 0.206). Conclusion The findings of this study suggest that a biopsy diagnosis of ASAP ± HGPIN, on either initial or surveillance biopsy, provides support for earlier repeat mpMRI and/or re-biopsy. This may assist in directing to early re-biopsy those patients likely to have intermediate- and high-risk prostate cancer.