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.