Atypical small acinar proliferation at index prostate biopsy: rethinking the re-biopsy paradigm

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.

A new ASAP Scoring System and Risk Table to predict second prostate biopsy outcomes

Introduction

This study aimed to discuss the necessity of a second prostate biopsy in patients with atypical small acinar proliferation (ASAP) and to develop a scoring system and risk table to be used as new criteria for a second biopsy.

Material and methods

The study reviewed the data of 2,845 patients who underwent transrectal ultrasonography-guided prostate biopsy in the period between January 2008 and May 2019. A total of 128 patients with ASAP were included in the study. The tPSA, fPSA, f/tPSA, and PSA-density levels before the first and second biopsies and changes in the measured levels between the values obtained before the first and the second biopsies were recorded. The ASAP Scoring System and Risk Table (ASS-RT) was evaluated before the second biopsy.

Results

The mean age of 128 patients with ASAP was 62.9 ±7.8 years. The ASS-RT scores of prostate cancer patients were significantly higher compared to patients without prostate cancer (p = 0.001). In the ROC curve analysis of ASS-RT, the area under the curve was 0.804 and the standard error was 0.04. The area under the ROC curve was significantly higher than 0.5 (p = 0.001). The cut-off point of ASS-RT scores in diagnosing cancer was ≥ 7 with 60.8% sensitivity and 80.5% specificity.

Conclusions

The cut-off value of 7 determined for the ASS-RT score in this study suggests that patients with ASS-RT scores of ≥ 7 should undergo a second prostate biopsy. We think that there may be no need for a second biopsy if the ASS-RT score is < 7, especially for low-risk patients.

Atypical small acinar proliferation and its significance in pathological reports in modern urological times

Atypical small acinar proliferation is a histopathological diagnosis of unspecified importance in prostate needle-biopsy reports, suggestive but not definitive for cancer. The terminology corresponds to some uncertainty in the biopsy report, as the finding might represent an underlying non-cancerous pathology mimicking cancer or an under-sampled prostate cancer site. Therefore, traditional practice favors an immediate repeat biopsy. However, in modern urological times, the need of urgent repeat biopsy is being challenged by some authors as in the majority of cases, the grade of cancer found in subsequent biopsy is reported to be low or the disease to be non-significant. On the other hand, high risk disease cannot be excluded, whereas no clinical or pathological factors can predict the final outcome. In this review, we discuss the significance of the diagnosis of atypical small acinar proliferation in the biopsy report, commenting on its importance in modern urological practice.