RER(+) phenotype in prostate intra-epithelial neoplasia associated with human prostate-carcinoma development

High-grade prostatic intraepithelial neoplasia

High-grade prostatic intraepithelial neoplasia (HGPIN) has been established as a precursor to prostatic adenocarcinoma. HGPIN shares many morphological, genetic, and molecular signatures with prostate cancer. Its predictive value for the development of future adenocarcinoma during the prostate-specific antigen screening era has decreased, mostly owing to the increase in prostate biopsy cores. Nevertheless, a literature review supports that large-volume HGPIN and multiple cores of involvement at the initial biopsy should prompt a repeat biopsy of the prostate within 1 year. No treatment is recommended for HGPIN to slow its progression to cancer.

The 3-dimensional structure of isolated and small foci of prostatic adenocarcinoma: the morphologic relationship between prostatic adenocarcinoma and prostatic intraepithelial neoplasia

BACKGROUND

Transitional histopathologic changes from high-grade prostatic intraepithelial neoplasia (HGPIN) into early prostatic adenocarcinoma (PAC) have not been well studied to date. To investigate the histogenesis of PAC, we examined isolated and small foci of PAC (ISPAC) found in prostatectomy specimens and the 3-dimensional structure of these foci.

DESIGN

Twelve consecutive radical prostatectomy specimens having ISPAC, performed for peripheral zone PAC (10 cases) and for transitional zone PAC (2 cases), of Gleason score were studied. One to 2 tissue blocks with representative sections were used.

RESULTS

Eight ISPAC, with Gleason score 3 + 3 had complete serial sections of the entire lesion. PAC consisted of continuous, tortuous and branching tubules and acini arising from benign ducts displaying: (a) HGPIN in 5 ISPAC and (b) no HGPIN in 3 ISAPC. At the junctions between benign epithelia with or without HGPIN and malignant epithelia, there were transitional lesions with HGPIN involving small ducts and acini.

CONCLUSIONS

PAC develops as a result of multiple outpouchings of the epithelium with formation of small ducts and acini showing cytologic atypia and gradual or abrupt loss of basal cells. Grade 3 ISPAC consists of a system of continuous duct pushing into the stroma. There is also evidence suggestive of HGPIN as being both a precursor lesion and an accompanying lesion of PAC.

Potential pathologic markers for prostate chemoprevention studies

The field of exploring potential biomarkers for prostate cancer prevention continues to expand rapidly. In addition to a limited scope of histologic alterations, mainly PIN, a growing array of promising technologies (eg, computer-assisted analysis), and molecules involved in cell-cycle regulations, angiogenesis, and structural and numerical chromosomal alterations are potential candidates for surrogate endpoint biomarkers for prevention trials. Before any these potential candidates are adopted, however, the technical, interpretational, and validation requirements must be satisfied. More important, it is crucial to demonstrate that modulation of the frequency of the biomarker decreases the rate of cancer development.

Can the number of cores with high-grade prostate intraepithelial neoplasia predict cancer in men who undergo repeat biopsy?

OBJECTIVES

To evaluate whether the presence of, or the number of cores containing, high-grade prostatic intraepithelial neoplasia (PIN) found in men who underwent initial extended multisite biopsy could predict which men would have prostate cancer on subsequent repeat biopsies.

METHODS

Between June 1997 and January 2003, 1086 men underwent initial prostate biopsy for early detection of prostate cancer using an extended multisite biopsy scheme. Of these, 175 men without cancer underwent at least one repeat biopsy (range one to three; median interval between biopsies, 3 months). Among these 175 patients, 47 had high-grade PIN on initial biopsy.

RESULTS

The initial extended biopsy identified cancer in 33.8% (367 of 1086) and high-grade PIN in 20.8% (226 of 1086). The incidence of high-grade PIN only in patients found to have cancer on initial biopsy was 29.7% (109 of 367). The presence of high-grade PIN was associated with concurrent prostate cancer at the initial biopsy (P <0.0001). Overall, repeat biopsy identified cancer in 18.3% of the 175 men. Of the 47 men with high-grade PIN, 5 (10.6%) were found to have cancer on repeat biopsy. The number of biopsy specimens positive for high-grade PIN on initial biopsy was not associated with the likelihood of prostate cancer on repeat biopsy. Multivariate logistic regression analysis showed that neither the presence of high-grade PIN nor the number of cores containing high-grade PIN on initial biopsy were predictors for prostate cancer on repeat biopsy.

CONCLUSIONS

The number of cores positive for high-grade PIN was not predictive for cancer on repeat biopsy.

High-grade prostatic intraepithelial neoplasia

High-grade prostatic intraepithelial neoplasia (PIN) is now accepted as the most likely preinvasive stage of adenocarcinoma, almost two decades after its first formal description. PIN has a high predictive value as a marker for adenocarcinoma, and its identification warrants repeat biopsy for concurrent or subsequent invasive carcinoma. The only method of detection is biopsy; PIN does not significantly elevate serum prostate-specific antigen (PSA) concentration or its derivatives and cannot be detected by current imaging techniques, including ultrasound. Most patients with PIN will develop carcinoma within 10 years. PIN is associated with progressive abnormalities of phenotype and genotype, which are similar to cancer rather than normal prostatic epithelium, indicating impairment of cell differentiation with advancing stages of prostatic carcinogenesis. Androgen deprivation therapy decreases the prevalence and extent of PIN, suggesting that this form of treatment may play a role in chemoprevention.

Identification of isolated and early prostatic adenocarcinoma in radical prostatectomy specimens with correlation to biopsy cores: clinical and pathogenetic significance

Prostatic adenocarcinoma (PAC) is a multifocal disease. In this study, we identified isolated and small foci of PAC (ISPAC) in radical prostatectomy specimens, described the histopathologic features, investigated their zonal distribution in the prostate and their relationship with large tumor nodules, and correlated the findings with those of preceding biopsy cores. One hundred and thirty radical prostatectomy specimens performed for PAC or for urothelial carcinoma of the urinary bladder with incidental PAC were reviewed for identification of ISPAC. Prostates were serially sectioned in the horizontal plane and submitted in toto for microscopic examination. ISPAC were defined as foci of PAC measuring less than 3 mm in maximum diameter. There were 461 ISPAC identified in 114 cases. They were distributed in the transitional zone (TZ) (18 foci), the apex (73 foci), the anterior horn of the non-TZ (NTZ) (118 foci), the base (8 foci), and the remaining NTZ (244 foci). ISPAC usually consisted of groups of small acini with a GS ranging from 2 to 7 (3 + 4). GSs of ISPAC consisted of single grade or two consecutive grades equal to or lower than those of the main PAC. ISPAC were more often located in close proximity to large tumor nodules. The number of ISPAC increased with the tumor volume up to 3 cm3, then decreased as the PAC became more extensive (p value = 0.02, statistically significant). Prostates with NTZ PAC <1.5 cm3 and TZ PAC or prostates containing 4 or more than 4 ISPAC tended to be frequently associated with small foci of PAC in biopsy cores In this study, we identified ISPAC that likely represent foci of PAC in early development and account for the multicentricity and heterogeneity of PAC. ISPAC in the NTZ were common and may account for small foci of PAC or atypia in biopsy cores. Although these small foci of PAC or atypia in biopsy cores without accompanying higher GS PAC were often associated with significant PAC, they may also occasionally represent insignificant or vanishing PAC in subsequent radical prostatectomies.

High-grade prostatic intraepithelial neoplasia and prostate cancer risk reduction

High-grade prostatic intraepithelial neoplasia (PIN) is the earliest accepted stage in carcinogenesis, possessing most of the phenotypic and biochemical changes in cancer without invasion of the basal membrane of the acini. The support for high-grade PIN as the main premalignant lesion of prostate cancer is based on several lines of evidence derived from prostate cancer animal models, epidemiological, morphological, genetic, and molecular studies. The incidence of high-grade PIN averages 9% (range 4-16%) in prostate biopsies, representing 115,000 new cases of high-grade PIN diagnosed each year in the United States. Performing saturation prostate biopsies to rule out any coexistent prostate cancer followed by every 3-6 month serial repeated prostate biopsies is currently the only way in which to manage patients found to have high-grade PIN. Medical therapy for high-grade PIN may easily become the mainstay treatment for high-grade PIN. Treatment of high-grade PIN appears to be of clinical benefit notwithstanding the potential for prostate cancer risk reduction. These clinical benefits would reduce morbidity, enhance quality of life, delay surgery or radiation, and increase the interval for surveillance requiring invasive procedures.

Molecular disorders in transitional vs. peripheral zone prostate adenocarcinoma

Loss of heterozygosity (LOH) and microsatellite instability (MSI) have been shown to be mechanisms for tumor-suppressor gene inactivation in human oncogenesis. In our study, we examined LOH and MSI using 16 polymorphic markers of DNA for chromosomes 1, 3, 7, 8, 10 and 11. Microdissected tumor samples were isolated from 32 patients, representing 11 foci of incidentally discovered prostate cancer of the transitional zone (TZ), 12 prostate cancer of the peripheral zone (PZ) and 10 of high-grade PIN. We found loss of heterozygosity in the TZ group in 91% of informative cases (10/11) with al least 1 marker compared to 58% of cases (7/12) in PZ group and 70% of cases (7/10) in the HGPIN group. Chromosome 7 showed the highest rate of allelic loss in all 3 categories, with loss of 43% of loci in PIN, 37% in TZ tumors and 31% in PZ tumors. At chromosome 11, LOH was detected in 26% of loci in the TZ group, in 7% of loci in the PZ group and in 13% of loci in the PIN group. On chromosome 8, the PZ and HGPIN group showed allelic loss in 22% and 21% of loci, respectively, compared to 10% detected in the TZ group. The TZ group showed a significant higher rate of allelic instability compared to that observed in tumor samples from the peripheral zone: 73% of cases (8/11) showed genetic alterations (RER+ phenotype) in at least 4 loci analyzed compared to 8% and 10% in the PZ and HGPIN groups, respectively (p = 0.0006). These data suggest that transitional zone carcinoma and peripheral zone carcinoma display distinct and specific genetic alterations in different chromosomes. This diversity may help explain biologic and clinical differences between carcinomas arising in these distinct zones of the prostate. Also our results strongly suggest that the RER+ mutator phenotype could be linked to early development of transitional zone prostate carcinoma.

Histological markers of risk and the role of high-grade prostatic intraepithelial neoplasia

The marked discrepancy between the prevalence of preclinical prostate cancer and the incidence of clinically manifest disease indicates a long latency phase and significant heterogeneity in the progression potential of early neoplastic lesions. There are a variety of histologic changes within prostatic epithelium that have been termed atypical or dysplastic. The 2 most widely studied of these lesions are prostatic intraepithelial neoplasia (PIN) and atypical adenomatous hyperplasia (AAH). Although associations between AAH and adenocarcinoma are spurious, those linking high-grade PIN (HGPIN) to cancer are far more established. There is a significantly increased risk for patients with isolated HGPIN to have prostate cancer confirmed on subsequent biopsy, suggesting that HGPIN is a marker for prostate carcinoma in addition to its potential role as a premalignant lesion. Autopsy studies reveal that HGPIN is found in association with cancer in 63% to 94% of malignant and 25% to 43% of benign prostates. Data on age and race reveal that African American men develop more extensive HGPIN at a younger age than white men. A wide spectrum of molecular/genetic abnormalities appears to be common to both HGPIN and prostate cancer. Data loss of 8p, 10q, 16q, 18q, and gain of 7q31, 8q, multiple copies of the c-myc genes, along with changes in chromatin texture, telomerase activity, cell cycle status, and proliferative indices collectively suggest that HGPIN is intermediate between benign epithelium and prostatic carcinoma with respect to these markers. These data indicate that HGPIN is important in neoplastic progression, and may present an appropriate target/marker for chemoprevention.

Cellular and molecular pathology of prostate cancer precursors

Prostate cancer is usually heterogeneous and multifocal, with diverse clinical and morphologic manifestations. Current understanding of the molecular basis for this heterogeneity is limited, particularly for prostatic intraepithelial neoplasia (PIN), the only putative precursor which can be identified according to morphologic criteria. However, it is likely that prostatic adenocarcinoma might arise from precursor lesions other than PIN, although these cannot be recognized with certainty at the present time. In this review, we summarize the current state of knowledge regarding the cell-biological and genetic bases for linking PIN and prostatic adenocarcinoma. It is conceivable that a stem cell of basal phenotype, or an amplifying cell, is the target of prostatic carcinogenesis. Prominent genetic heterogeneity is characteristic of both PIN and carcinoma; and multiple foci of PIN arise independently within the same prostate. This observation suggests that a field effect probably underlies prostatic neoplasia. Multiple foci of cancer also often arise independently, lending additional support to this hypothesis. The strong genetic similarities between PIN and cancer strongly suggest that evolution and clonal expansion of PIN, or other precursor lesions, may account for the multifocal etiology of carcinoma. Uncertainties with respect to identification of those precursor lesions which are most likely to progress to invasive and metastatic prostate cancer reinforce the requirement for objective immunohistochemical or molecular biological markers of the aggressive phenotype.