Atypical small acinar proliferation (ASAP): Is a repeat biopsy necessary ASAP? A multi-institutional review

What is cancer? A focus on Grade Group 1 prostate cancer

Since the widespread adoption of prostate-specific antigen-based screening for prostate cancer, the prevalence of Grade Group 1 (GG1) prostate cancer has risen. Historically, these patients were subjected to overtreatment of this otherwise indolent disease process, leading to significant quality-of-life detriments. Active surveillance as a primary management strategy has allowed for a focus on early detection while minimising morbidity from unnecessary intervention. Here we provide a comprehensive overview of the characteristics of GG1 prostatic adenocarcinoma, including its histological features, genomic differentiators, clinical progression, and implications for treatment guidelines, all supporting the movement to reclassify GG1 disease as a non-cancerous entity.

miRNAs as molecular biomarkers for prostate cancer

MicroRNAs (miRNAs) are short noncoding RNA able to regulate specific mRNA stability, thus influencing target gene expression. Disrupted levels of several miRNA have been associated with prostate cancer, the leading cause of cancer death among men and the fifth leading cause of death worldwide. Here, we investigated whether miR-145, miR-148, and miR-185 circulating levels in plasma could be used as molecular biomarkers, to allow distinguishing between individuals with benign prostatic hyperplasia, precancerous lesion, and prostate cancer. In this study, we recruited 170 urological clinic patients with suspected prostate cancer who underwent prostate biopsy. Total RNA was isolated from plasma, and TaqMan MicroRNA assays were used to analyze miR-145, miR-185, and miR-148 expression. First, differential miRNA expression among patient groups was evaluated. Then, miRNA levels were combined with clinical assessment outcomes, including results from invasive tests, using multivariate analysis to examine their ability in discriminating among the three patient groups. Our results suggest that miRNA is a promising molecular tool for clinical management of at-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.

Rate of clinically significant prostate cancer on repeat saturation biopsy after a diagnosis of atypical small acinar proliferation

BACKGROUND

Atypical small acinar proliferation (ASAP) occurs in approximately 5% of prostate biopsies. Approximately 30%-40% of these patients may develop prostate cancer (PCa) within a 5-year period, often not clinically significant. Current guidelines recommend a repeat biopsy within 3-6 months after the initial diagnosis, but it seem not to be the best strategy.

METHODS

Objectives-evaluating the natural history of ASAP, stratifying the risk of csPCa after ASAP, identifying predictive factors of PCa after atypical diagnosis. Materials and methods-retrospective single-institutional study on patients undergoing prostate biopsy for suspicious PCa (2005-2016). We evaluated the incidence of overall PCa, intermediate-high risk of PCa and csPCa in case of ASAP, according to D'Amico classification and Epstein modified criteria.

RESULTS

Out of 4.567 patients undergoing prostate biopsy, ASAP was detected in 2.6% of cases. All patients with ASAP underwent repeat saturation biopsy within 6 months and PCa was diagnosed in 34.5%. According to D'Amico classification, 26%, 5.9%, and 2.5% had low, intermediate, and high-risk disease, respectively. According modified Epstein criteria, the incidence of csPCa was 12.6%. LRT showed that the overall probability to develop PCa doubled when PSA density (PSAD) moved from values lower than 0.13 ng/ml/cc to class 0.13-0.30 ng/ml/cc, and it tripled when PSAD was higher than 0.30 ng/ml/cc.

CONCLUSIONS

The rate of csPCa in patients with an initial diagnosis of ASAP who had repeat biopsy was 12.6%. The overall PCa rate was 34.5%. Among patient undergoing RP, an upgrading from ncsPCa to csPCa was reported in 35% of cases. PSAD is the only predictive factor directly associated to the risk of developing PCa on repeat biopsy. These findings suggest that immediate repeat biopsy remains the correct strategy in absence of novel predictor factors and non-invasive diagnostic evaluations.

Natural history of widespread high grade prostatic intraepithelial neoplasia and atypical small acinar proliferation: should we rebiopsy them all?

OBJECTIVE

To evaluate the premalignant potential of high-grade prostatic intraepithelial neoplasia (HGPIN) and atypical small acinar proliferation (ASAP).

METHODS

Patients diagnosed with monofocal HGPIN (mHGPIN), widespread HGPIN (≥4 cores, wHGPIN) and/or ASAP who underwent at least one rebiopsy during their follow-up, were enrolled. All enrollment biopsies underwent central pathologic revision. Risks for PCa were estimated using Fine and Gray method for competing risk.

RESULTS

Pathologic revision changed the original diagnosis in 32.3% of cases. Among 336 cases enrolled, PCa was diagnosed in 164 (48.8%), and more specifically in 20 (30.3%) mHGPIN, 10 (34.5%) wHGPIN, 101 (54.0%) ASAP, and 33 (61.1%) HGPIN + ASAP (mean follow-up 124 months). Most PCa were Gleason score 6(3 + 3) (51.0%) and 7(3 + 4) (34.3%). On multivariate analysis, HGPIN + ASAP (HR 2.76, p < 0.001) and ASAP alone (HR 2.41, p < 0.001) were the only lesions significantly associated with PCa development. Of all cancers detected, 64.3% were at first rebiopsy. A rebiopsy performed within 3 months after ASAP diagnosis had a 45% chance of finding PCa. At Kaplan-Meier survival curves, median PCa-free survival was 48.1 months for HGPIN + ASAP and 64.9 months for ASAP (p 0.0005 at Log-rank test). At 1 year, 70% of HGPIN + ASAP, 73% of ASAP, 89% of wHGPIN, and 84% of mHGPIN were PCa-free.

CONCLUSION

The diagnosis of ASAP and HGPIN strongly relies on the expertise of dedicated uro-pathologists. Finding of ASAP is a strong risk factor for a subsequent PCa diagnosis, advising a rebiopsy, possibly within 3 months. m/wHGPIN should not be routinely rebiopsied.

Clinical significance of the De Ritis ratio for detecting prostate cancer in a repeat prostate biopsy

Purpose

We evaluated factors predicting a positive repeat biopsy result in patients with an initial negative prostate biopsy result.

Materials and Methods

This study included 124 patients in whom prostate cancer (PCa) was not detected in the initial transrectal ultrasound-guided prostate biopsy and who underwent repeat biopsy from January 2011 to December 2017. Patients without PCa in both initial and repeat prostate biopsies were designated as group 1 (n=82), and those in whom PCa was detected on a repeat prostate biopsy were designated as group 2 (n=42). Among group 2 patients, 6 had insignificant PCa according to the Epstein criteria and were combined with group 1 patients to make up group A (n=88). Patients with significant PCa were categorized as group B (n=36). We compared clinicopathologic characteristics between the groups.

Results

Multivariate analysis showed that age (p=0.018) and detection of atypical small acinar proliferation (ASAP) or ≥3 cores of high-grade prostatic intraepithelial neoplasia (HGPIN) (p=0.011) on the initial biopsy were predictive factors for a positive result on a repeat biopsy. When we compared group A and group B, age (p=0.004) and the De Ritis ratio (p=0.024) were significantly higher in group B in the multivariate analysis.

Conclusions

Age and the detection of ASAP or ≥3 cores of HGPIN on the initial biopsy were associated with detection of PCa on a repeat biopsy. Age and the De Ritis ratio were found to be predictive factors for the detection of clinically significant PCa on a repeat biopsy.

In Search for risk predictors at the microscopic scenario of a negative biopsy. A systematic review

INTRODUCTION

In cases of persistent suspicion of prostate cancer (PC), repeat prostate biopsies (PB) are frequently performed in spite of their low yield. In the context of a negative PB, there is a microscopic scenario (MS), which we define as the group of recognizable non-neoplastic lesions. While some of these lesions seem to have a protective effect, the existence of others increases the risk of PC detection in posterior PB. The objective of this systematic review is to identify the lesions that may belong to the MS of a negative PB and analyse the current evidence of their association with the risk of detecting PC in subsequent PBs.

EVIDENCE ACQUISITION

Two independent reviewers conducted a literature search on Medline, Embase and Central Cochrane with the following search terms: small acinar proliferation, ASAP, prostatic intraepithelial neoplasia, HGPIN, adjacent small atypical glands, pinatyp, atrophy, proliferative inflammatory atrophy, pia, prostatic inflammation, prostatitis and prostate cancer. 1,015 references were first identified, and 57 original articles were included in the study, following the PRISMA declaration and the PICO selection principles.

EVIDENCE SYNTHESIS

Atypical small acinar proliferation is associated with PC detection in repeat PB with rates ranging between 32 and 48%. High-grade prostatic intraepithelial neoplasia (HGPIN) is related to PC in 13 to 42% of cases. Studies show that HGPIN, when multifocal, is a significant independent risk factor for PC. Prostatic atrophy, inflammatory proliferative atrophy and prostatic inflammation seem to act as protective factors on the detection of PC in repeat PB. On the other hand, the risk of PC detection reduces significantly in male patients with multifocal HGPIN and coexistent PIA.

CONCLUSIONS

The MS of a negative PB may include atypical small acinar proliferation, HGPIN, prostatic atrophy, inflammatory proliferative atrophy and prostatic inflammation lesions, since they all seem to be associated with the risk of PC detection in repeat PB. This review has led us to create the hypothesis that the MS of a negative PB might be a valuable and useful tool when considering repeat PB.

Comparison of diagnostic efficacy by two urine PCA3 scores in prostate cancer patients undergoing repeat biopsies

INTRODUCTION

Urine prostate cancer gene 3 (PCA3) is significantly elevated in patients with prostate cancer and can be used for the diagnosis of prostate cancer, but its cutoff value is still controversial.

EVIDENCE ACQUISITION

We searched the database on urine PCA3 in the diagnosis of prostate cancer, such as Medline, Web of Science, the Cochrane Library and Embase. Meta-analysis was performed using the random effect model and the sensitivity, specificity, diagnostic odds ratio, and area under the ROC curve (SROC) were calculated.

EVIDENCE SYNTHESIS

Our meta-analysis included nine studies on PCA3 scores in a total of 1721 suspected prostate cancer patients. When urine PCA3 score was 20, we obtained sensitivity of 0.83, specificity of 0.40, diagnostic odds ratio of 3.11, and the area under the SROC curve was 0.6842 (Q value 0.6404). When urine PCA3 score was 35, we found a lower sensitivity of 0.66, a higher specificity of 0.63 and a relatively lower diagnostic odds ratio of 2.84. The area under the SROC curve was 0.6715, which was slightly lower than urine PCA3 score 20.

CONCLUSIONS

Our meta-analysis suggested that when the PCA3 score cutoff value was 20, the unnecessary puncture was reduced and obtained a higher diagnostic efficacy.

The role of the serum testosterone levels as a predictor of prostate cancer in patients with atypical small acinar proliferation at the first prostate biopsy

The current literature does not support the usefulness of clinical markers on predicting which patients with atypical small acinar proliferation (ASAP) are more likely to progress to prostate cancer (PCa). Androgens have long been considered to be the potential risk factors for PCa. However, the role of testosterone is controversial. The present study aims to analyze the relationship between serum testosterone (TS) levels and the diagnosis of PCa after a first prostate biopsy in patients affected by ASAP. This retrospective study included 143 patients diagnosed with ASAP in an initial transrectal ultrasound-guided prostate biopsy for suspicious PCa according to the European Association of Urology guidelines. Their TS levels, age, PSA, prostate volume, digital rectal examination, and prostate biopsy Gleason score (GS) were collected retrospectively for statistical analysis. All patients included in the study had a second biopsy and were suitable for further analysis. Re-biopsy was carried out 3-6 months after the first diagnosis of ASAP. Low and normal TS groups were composed of 29 (20.3%) and 114 (79.7%) patients, respectively. The diagnosis of the second biopsy was ASAP in 25.2% and PCa in 36.4% of patients. The comparison between patients with PCa and those with negative or an ASAP result in the second biopsy reported that men with cancer had significantly higher levels of TS (P < 0.001). However, there was no statistically significant association between GS postbiopsy and TS (P = 0.324). Our experience demonstrated that eugonadal patients may be a clinical risk factor for the diagnosis of PCa on re-biopsy after ASAP diagnosis than hypogonadal.

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

PURPOSE

Guidelines for atypical small acinar proliferation (ASAP) diagnosed on prostate biopsy recommend repeat biopsy within 3-6 months after diagnosis. We sought to discern the rate of detecting clinically significant prostate cancer on repeat biopsy and predictors associated with progression.

MATERIALS AND METHODS

We performed a retrospective chart review of patients who underwent prostate biopsy at our institution from January 1, 2008, to December 31, 2015. Gleason grade group (GGG) system and D'Amico stratification were used to report pathology and risk stratification, respectively. Logistic and linear regression analyses were performed.

RESULTS

A total of 593 patients underwent transrectal ultrasound-guided prostate biopsy, of which 27 (4.6%) had the diagnosis of ASAP. Of these, 11 (41%) had a repeat biopsy. Median time from diagnosis to repeat biopsy was 147 days (IQR 83.5-247.0). Distribution across the GGG system on repeat biopsy was as follows: 7 (63.6%) benign, 3 (27.3%) GG1, and 1 (9.1%) GG2. ASAP was not associated with subsequent diagnosis of clinically significant prostate cancer (OR 0.46, 95% CI 0.064-3.247, P = 0.432). There was no association between ASAP and high cancer risk (ASAP: β = - 0.12; P = 0.204).

CONCLUSIONS

Patients diagnosed with ASAP managed according to guideline recommendations are more likely diagnosed with benign pathology and indolent prostate cancer on repeat biopsy. These findings support prior studies suggesting refinement of guidelines in regard to the appropriateness and timeliness of repeat biopsy among patients diagnosed with ASAP.

Atypical Small Acinar Proliferation and High Grade Prostatic Intraepithelial Neoplasia: Should We Be Concerned? An Observational Cohort Study with a Minimum Follow-Up of 3 Years

Introduction

Atypical small acinar proliferation (ASAP) and high grade prostatic intraepithelial neoplasia (HGPIN) are considered precancerous. We aimed to measure the rate of repeat biopsy and adenocarcinoma in patients with ASAP and HGPIN and identify any clinico-pathologic parameters at diagnosis of ASAP/HGPIN that are predictive of adenocarcinoma.

Materials and Methods

Patients with a diagnosis of ASAP/HGPIN with no previous or concomitant cancer were identified. Prostate specific antigen (PSA) and magnetic resonance imaging (MRI) changes were monitored. Re-biopsy was at clinician discretion.

Results

Nineteen were diagnosed with ASAP and 17 with HGPIN. Seven with ASAP (37%) and 6 with HGPIN (35%) underwent re-biopsy. Three (16%) with ASAP and 5 with HGPIN (29%) were diagnosed with adenocarcinoma. The difference in cancer detection rates between ASAP and HGPIN was not significant (p = 0.35). Five (14%) in total required definitive therapy for adenocarcinoma. Twenty-three (64%) did not undergo repeat biopsy. Parameters at diagnosis of HGPIN and ASAP, including PSA, prostate volume and PSA density, were compared between the cancer and non-cancer cohorts with none found to be predictive of adenocarcinoma.

Conclusion

By monitoring PSA and MRI changes, we managed to spare re-biopsy in two-thirds of patients. Further evaluation is necessary to characterize a surveillance protocol in these populations.

Atypical small acinar proliferation and two or more cores of high-grade intraepithelial neoplasia on a previous prostate biopsy are significant predictors of cancer during a transperineal template-guided saturation biopsy aimed at sampling one core for each 1 mL of prostate volume

Objective

The objective of this study was to evaluate whether high-grade prostatic intraepithelial neoplasia (HGPIN) and atypical small acinar proliferation (ASAP) predict prostate cancer (PCa) during repeat transperineal template saturation biopsy with a high number of cores per prostate volume in patients with persistent clinical suspicion of PCa who underwent at least one previous negative transrectal ultrasound (TRUS)-guided biopsy.

Methods

We retrospectively evaluated 135 consecutive patients with persistent clinical suspicion of PCa, despite a set of negative TRUS-guided biopsies and increasing prostate-specific antigen levels; abnormal findings on digital rectal examination, TRUS, or magnetic resonance imaging; previous biopsy showing HGPIN; and previous biopsy showing atypical glands. Transperineal template saturation biopsy (TTSB) was performed at 5mm intervals to sample one core for each 1 mL of prostate volume.

Results

The median rate of biopsy cores per prostate volume was 1.00 (range: 0.75–1.39). The PCa detection rates in patients who were diagnosed with HGPIN, or had two or more cores of HGPIN or ASAP, were 53% (9/17), 89% (8/9), and 83% (10/12), respectively. Two or more HGPIN cores and ASAP were positive predictors of PCa on TTSB. The high-grade cancer rates (Gleason score [GS] ≥7) in patients with ASAP and two or more cores of HGPIN were 20% and 80%, respectively. The cancer detection rate represented by a GS score ≥8 in patients with ASAP or two or more cores of HGPIN at a previous TRUS-guided biopsy was 5.5% (1/18).

Conclusion

ASAP or two or more cores of HGPIN at a previous TRUS-guided biopsy strongly indicated the presence of PCa on TTSB.

Managing high-grade prostatic intraepithelial neoplasia (HGPIN) and atypical glands on prostate biopsy

Prostate biopsy is the gold standard for diagnosing prostate cancer and reliable pathological assessment is essential for guiding management. Research efforts over the past few years have aimed to establish a more universal approach to management according to pathological grading; however, high-grade prostatic intraepithelial neoplasia (HGPIN) and atypical glands suspicious for carcinoma are two diagnoses without standardized follow-up and treatment pathways. Much of this uncertainty is due to limited evidence describing the subsequent rates of cancer and high-grade cancer when HGPIN or atypical glands are detected on initial biopsy. Fortunately, data from the past decade have shed light on these phenomena, and an improved understanding of the implications of the presence of HGPIN and atypical glands on prostate biopsy means that clinical recommendations can be made for the management of patients with these diagnoses.

Typing the atypical: Diagnostic issues and predictive markers in suspicious prostate lesions

As much as 5% of prostate biopsies yield findings equivocal for malignancy even for skilled uropathologist; such "grey zone" lesions have been addressed in many ways, although the acronym ASAP (atypical small acinar proliferation) is the most widely used when referring to an atypical focus suspicious, but not diagnostic, for malignancy. Since the introduction of this diagnostic category more than 20 years ago, debate has ensued over its histological characterization and clinical significance. Pathology reporting of ASAP, commonly based on strict morphological criteria and traditional immunohistochemical markers such as basal cell antibodies, has been improved by recent availability of novel immunohistochemical markers such as AMACR and ERG. Further pathological issues, such as the role of pre-analytical variables, number of tissue levels, interobserver variability, and association with prostatic intraepithelial neoplasia also play a role in the optimal assessment of ASAP. Apart from diagnostic issues, a major issue is ASAP predictive value for prostate cancer on repeat biopsy. Therefore, attempts have been made to identify clinical and biological parameters that could predict subsequent diagnosis of malignancy as well as define time and modality of repeat biopsy. Finally, pathological features of cancers detected after a previous ASAP diagnosis are compared with those diagnosed at first prostate biopsy.

Racial Variation in the Outcome of Subsequent Prostate Biopsies in Men With an Initial Diagnosis of Atypical Small Acinar Proliferation

BACKGROUND

African American (AA) men are known to have more aggressive prostate cancer (PCa) compared with Caucasian American men. We sought to determine predictors of subsequent detection and risk stratification of PCa in a racially diverse group of men with atypical small acinar proliferation (ASAP) on initial prostate biopsy.

MATERIALS AND METHODS

A retrospective analysis was conducted on data from men with ASAP on initial prostate biopsy who subsequently received confirmatory biopsies between September 2000 and July 2015. Biopsies with more than 3 years between initial and confirmatory biopsies were excluded. Race, age, body mass index, transrectal ultrasound volume, serum prostate-specific antigen (PSA), PSA velocity, PSA density, and elapsed time between biopsies were assessed for predictive value in subsequent PCa diagnosis after an initial finding of ASAP.

RESULTS

Of 106 men analyzed, 75 (71%) were AA and 31 (29%) were non-AA. Baseline variables revealed AA men had higher PSA levels, PSA velocity, and PSA density (all P < .05). PCa was diagnosed in subsequent biopsy in 42 (40%) patients without significant racial variation; 30 (40%) AA versus 12 (39%) non-AA. Of the 42 PCa patients, 25 (24%) met Epstein criteria for significant disease without racial variation; 18 (24%) AA versus 7 (23%) non-AA. Only 10 (9%) patients had any component of Gleason 4; 7 (9%) AA versus 3 (10%) non-AA. In multivariate analysis, increasing age, PSA level, and PSA density were significant predictors of PCa.

CONCLUSION

AA men diagnosed with ASAP on initial prostate biopsy do not have increased risk of PCa on confirmatory biopsy compared with non-AA men.

Incidence, grade and distribution of prostate cancer following transperineal template-guided mapping biopsy in patients with atypical small acinar proliferation

PURPOSE

To evaluate the role of transperineal template-guided mapping biopsy (TTMB) in patients with atypical small acinar proliferation (ASAP) diagnosed via transrectal ultrasound-guided needle biopsy (TRUS).

METHODS

In total, 132 consecutive patients with TRUS-diagnosed ASAP underwent TTMB by means of an anatomic-based technique with sampling of 24 biopsy regions. For each of the 24 regions, 1-3 biopsy cores were obtained (depending on prostate size). No patient underwent pre-biopsy MRI imaging. The Gleason score, location of each positive biopsy core, the number of biopsy cores and percent involvement of each core were recorded. Anterior versus posterior cancer distribution was determined for both low- and high-grade (Gleason score ≥7) cancer.

RESULTS

The mean patient age was 63.8 years with a mean PSA of 6.8 ng/mL. Of the 132 patients, 86 (65.2%) were diagnosed with prostate cancer. Of the entire cohort, 47 patients (54.7% of cancer patients and 35.6% of the entire cohort) were diagnosed with Gleason score ≥7. For both low- and high-grade cancers, the anterior gland and especially the anterior apex were the most common cancer locations.

CONCLUSION

In patients with ASAP, TTMB diagnosed prostate cancer in 65.2% of patients and 35.6% of the entire cohort had high-grade prostate cancer. A predilection for anterior-based cancers, especially the anterior apex, was identified. Our study may serve as a baseline reference for MRI-guided biopsy regimens.