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.

RNA-based markers in biopsy cores with atypical small acinar proliferation: Predictive effect of T2E fusion positivity and MMP-2 upregulation for a subsequent prostate cancer diagnosis

BACKGROUND

Atypical small acinar proliferation (ASAP) is a precursor lesion of prostate cancer (PC), and PC develops from this suspicious focus or an unsampled malignant gland nearby. However, PC-related molecular alterations that could guide the timing of repeat biopsies and help monitor PC risk in ASAP-diagnosed patients have not been investigated. The purpose of this study was to first investigate the expression of seven different PC-related RNAs that included serine 2 (TMPRSS2): erythroblastosis virus E26 oncogene homolog (ERG) gene (TMPRSS2-ERG, T2E) fusion, alpha-methylacyl-CoA racemase (AMACR), kallikrein related peptidase 3 (KLK3), androgen receptor (AR), prostate cancer specific antigen 3 (PCA3), and matrix metalloproteinases (MMP)-2 and 9.

METHODS

PC-related RNAs were evaluated using a real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) system in pathologically ASAP-diagnosed prostate biopsy cores from 55 patients presenting with a normal digital rectal examination and a PSA level of 4-10 ng/mL.

RESULTS

We detected that positive T2E fusion status (P = 0.013) and the expression of AMACR (P = 0.016), AR (P = 0.016) and MMP-2 (P = 0.013) were independently and significantly associated with PC risk in ASAP patients. There were also several statistically significant correlations between expression levels. Additionally, we demonstrated that T2E fusion positive ASAP patients with higher MMP-2 expression were more likely to be diagnosed with PC at a subsequent biopsy during the follow-up period (P = 0.003).

CONCLUSIONS

Although, more clinical validations are needed for the stratification of PC risk in ASAP-diagnosed biopsy cores, our current results indicate that the coexistence of T2E fusion positivity with MMP-2 upregulation may help clinicians adjust their biopsy timetable and/or assessment of PC risk in ASAP-diagnosed patients with a PSA level of 4-10 ng/mL.

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.

Differences in Postoperative Pathological Outcomes between Prostate Cancers Diagnosed at Initial and Repeat Biopsy

Purpose

We evaluated the differences in pathological outcomes between prostate cancers (PCas) diagnosed at initial and repeat biopsy.

Materials and Methods

We retrospectively reviewed the medical records of 287 patients who underwent radical retropubic prostatectomy from 2005 to 2010. We investigated preoperative factors, such as age, serum prostate-specific antigen (PSA), prostate volume (PV), digital rectal examination (DRE) results, biopsy schema, clinical stage, and number of prior biopsies, and postoperative pathological outcomes, including specimen volume, percent tumor volume, Gleason score (GS), tumor bilaterality, pathological stage, positive surgical margin (PSM), lymphovascular invasion (LVI), and perineural invasion (PNI). Patients were then classified into two groups by the number of prior biopsies (initial biopsy vs. repeat biopsy). We compared preoperative factors and postoperative pathological outcomes between the two groups.

Results

Of the 287 patients, 246 (85.7%) were diagnosed with cancer at the initial biopsy and 41 (14.3%) at the repeat biopsy. The repeat biopsy group was older (p=0.048), had a larger PV (p=0.009), had a significantly different biopsy schema (p<0.001), and had a lower (<10%) percentage tumor volume (p=0.016). In the multivariate analysis (after adjustment for biopsy schema, age, serum PSA, PV, and DRE), repeat biopsy was not an independent predictor of GS, tumor bilaterality, pathological stage, PSM, LVI, or PNI (p=0.212, 0.456, 0.459, 0.917, 0.991 and 0.827, respectively), but repeat biopsy could predict lower percentage tumor volume (p=0.037).

Conclusions

The pathological outcomes of PCas detected at repeat biopsy were not significantly different from those of PCas detected at initial biopsy except for a lower (<10%) percentage tumor volume.

Predictive factors of prostate cancer at repeat biopsy in patients with an initial diagnosis of atypical small acinar proliferation of the prostate

Purpose

The factors that predict prostate cancer detection on repeat biopsy were evaluated in patients with atypical small acinar proliferation (ASAP) on the initial biopsy.

Materials and Methods

From 2003 to 2008, 3,130 men with suspected prostate cancer underwent a prostate needle biopsy, and 244 (7.8%) were diagnosed as having ASAP. One hundred seventy of 244 patients were rebiopsied at least once more. They were classified into a prostate cancer group and a noncancer group according to the final pathological diagnosis. The database of rebiopsied patients included age, initial prostate-specific antigen (PSA), PSA density (PSAD), PSA velocity (PSAV), total prostate volume (TPV), and transitional zone volume of the prostate (TZV). We compared differences in the aforementioned parameters between the 2 groups.

Results

A total of 57 patients (33.5%) with ASAP were ultimately shown to have prostate cancer. Univariate analysis showed that PSAD (p=0.002), PSAV (p=0.001), TPV (p=0.035), and TZV (p=0.005) differed significantly between the cancer and noncancer groups. The results of the multivariate analysis showed that PSAD (p=0.022), PSAV (p<0.001), and TPV (p=0.037) had a statistically significant correlation with cancer detection.

Conclusions

PSAD, PSAV, and TPV are predictive factors of prostate cancer in patients with an initial diagnosis of ASAP of the prostate. Although repeat biopsy is mandatory irrespective of PSA values, the follow-up of PSA may help to estimate the probability of cancer in these men.

Pathologic results of radical prostatectomies in patients with simultaneous atypical small acinar proliferation and prostate cancer

PURPOSE

The incidence of adenocarcinoma on a subsequent biopsy following a diagnosis of atypical small acinar proliferation (ASAP) ranges from 34% to 60%. We reexamined radical prostatectomy (RP) specimens of patients diagnosed as having synchronous ASAP with prostate cancer (PCa) to evaluate pathological entities and the clinical significance of ASAP.

MATERIALS AND METHODS

From January 2007 to December 2008, a total of 118 patients who had been diagnosed with adenocarcinoma on prostate needle biopsy underwent RP. Forty-six of the 118 patients (39%) were diagnosed as having synchronous ASAP with PCa on the prostate needle biopsy. Using whole-mount sections and prostate mapping, we evaluated the RP specimens that were close sections to the ASAP on prostate needle biopsy. All tissues were examined by immunohistochemistry with high molecular weight cytokeratin (34betaE12), p63, and AMACR/P504S added to initial H&E stains by one pathologist.

RESULTS

Thirty-six of the 46 patients (78%) were diagnosed as having adenocarcinoma at sites of ASAP on the initial prostate needle biopsies. The Gleason score was 5 to 6 in 22 patients (61%), 7 in 3 (8%), and unknown due to multifocal and microfocal lesions in 11 (31%). The tumor volume of 14 of the 36 patients (39%) was 0.5 cc or less and was unknown due to multifocal and microfocal lesions in 8 (22%).

CONCLUSIONS

Most ASAP on initial prostate needle biopsy was a true pathological entity, in other words, prostatic adenocarcinoma. Aggressive approaches including more extended repeat biopsy with additional biopsy of the site of the ASAP are needed to diagnose PCa in patients with ASAP.