The extent and multicentricity of high-grade prostatic intraepithelial neoplasia in clinically localized prostatic adenocarcinoma

Extent and zonal distribution of prostatic intraepithelial neoplasia in patients with prostatic carcinoma in Japan: analysis of whole-mounted prostatectomy specimens

BACKGROUND

Prostatic intraepithelial neoplasia (PIN), an intraluminar proliferation of epithelial cells in ducts and acini, is divided into high-grade (HGPIN) and low-grade (LGPIN), based on morphologies. HGPIN is considered to be a putative precursor of prostatic adenocarcinoma (PCA). Information on PIN has been limited in Japan, because PIN had not been regarded as a precursor lesion for PCA.

METHODS

In this study, extent and zonal distribution of PIN together with its relationship with PCA were examined in totally embedded radical prostatectomy specimens obtained from 70 patients with PCA. Fifty-three patients received androgen deprivation therapy (castrated) and remaining 17 did not (noncastrated).

RESULTS

Frequency of HGPIN in noncastrated cases (76%) was much higher than that in castrated cases (26%) (P < 0.001). LGPIN showed the same tendency, but the difference was smaller. Difference in mean number of HGPIN in noncastrated and castrated cases (12.0 and 6.4, respectively) was more marked than in LGPIN (6.4 and 5.1, respectively). Reduction rate of mean size in HGPIN (26%) by the androgen deprivation therapy was larger than in LGPIN. When evaluated in noncastrated cases, the coexistence of PCA and HGPIN was found in 76% of cases in the nontransition and 53% in the transition zone. Close association of PCA and PIN (</=2 mm distance between lesions) was more frequently found in HGPIN (55% of lesions) than in LGPIN (37%) (P < 0.05). Frequency of close association of HGPIN with PCA was 65% in the nontransition and 35% in transition zone.

CONCLUSIONS

The present study from Japan supports the etiological importance of HGPIN in the development of PCA. The effect of androgen deprivation therapy is much more marked in HGPIN than in LGPIN.

Correlation of margin status and extraprostatic extension with progression of prostate carcinoma

BACKGROUND

The correlation of surgical margins and extraprostatic extension (EPE) with progression is uncertain with regard to prostate carcinoma patients treated by radical prostatectomy. The objective of this study was to define factors predictive of cancer progression; emphasis was placed on surgical margins and their relation to extraprostatic extension.

METHODS

The study group consisted of 377 patients who were treated by radical retropubic prostatectomy and bilateral pelvic lymphadenectomy at the Mayo Clinic between 1986 and 1993. All specimens were totally embedded and whole-mounted. Patients ranged in age from 41 to 79 years (mean, 65 years). Those with seminal vesicle invasion or lymph node metastasis and those treated preoperatively with radiation or androgen deprivation were excluded. Final pathologic T classifications were pT2a (41 patients), pT2b (237), and pT3a (99). Progression was defined as biochemical failure (prostate specific antigen [PSA] >0.2 ng/mL), clinical or biopsy-proven local recurrence, or distant metastasis. The mean follow-up was 5.8 years (range, 0.2-11.4 years). Seventy-nine patients who received adjuvant treatment within 3 months after surgery were excluded from survival analysis.

RESULTS

The overall margin positivity rate was 29%. Seventy-two patients (19%) had only positive surgical margins without evidence of EPE ("surgical incision"), 53 (14%) had only EPE, 37 (10%) had both, and 215 (57%) had neither. Positive margins were correlated with the finding of EPE (P = 0.003). Progression free survival rates at 5 and 10 years were 88% and 67%, respectively. In univariate analysis, preoperative PSA concentration, positive surgical margins, Gleason grade, cancer volume, and DNA ploidy were significant in predicting progression (P values, <0.001, <0.001, 0.01, 0.007, and <0.001, respectively). In multivariate analysis, margin status and DNA ploidy were independent predictors of progression (relative risk for margin status, 1.9; 95% confidence interval [CI], 1.1-3.4; P = 0.03; relative risk for DNA ploidy, 5.1; 95% CI, 2.4-10.9; P<0.001). Among patients with positive margins, 5-year progression free survival was 78% for those with negative EPE and 55% for those with positive EPE.

CONCLUSIONS

Surgical margin status and DNA ploidy were independent predictors of progression after radical prostatectomy. To improve cancer control, adjuvant therapy may be considered for patients with positive surgical margins or nondiploid cancer.

Histopathologic effects of three-dimensional conformal external beam radiation therapy on benign and malignant prostate tissues

We reviewed 137 prostate sextant needle biopsies from 137 patients obtained at a median of 35.7 months after three-dimensional conformal external beam radiation therapy (3DCRT). Thirty-one patients (23%) received 3 months of androgen deprivation therapy (ADT) before 3DCRT. We also retrospectively reviewed and assigned a combined Gleason score to the pre-3DCRT needle biopsies (97 patients) or transurethral resection of the prostate gland (1 patient). High-molecular-weight cytokeratin (34betaE12) and prostate-specific antigen (PSA) immunohistochemistry was performed in select cases. After 3DCRT, histopathologic changes in benign prostate gland consisted of glandular atrophy, cytologic atypia, and basal cell prominence. The benign glands showed intensely positive reactions with antibodies to high-molecular-weight cytokeratin (34betaE12) and negative to weakly positive reactions to PSA. Paneth cell-like change was seen in 44 (32%) of the biopsies, mucinous metaplasia in 29 (21%), luminal blue-tinged mucinous secretions in 14 (10%), and squamous metaplasia in 8 (6%). The changes in benign prostate tissues were similar between patients treated with ADT and 3DCRT and those treated with 3DCRT alone. After 3DCRT, we recognized two histologic patterns of prostate cancer: (1) prostate cancer showing radiation therapy (RT)-related changes characterized by PSA-positive/34betaE12-negative poorly formed glands or individual cells with abundant clear to finely granular cytoplasm, and (2) prostate cancer showing no apparent RT effect. High-grade prostatic intraepithelial neoplasia (PIN) was seen in 12 post-3DCRT biopsies (8.8%). The use of neoadjuvant ADT had a significant impact on the results of post-RT biopsy. Of the 31 patients treated with neoadjuvant ADT and 3DCRT, 3 (10%) had post-3DCRT biopsies showing prostate cancer without RT effect compared to 44 of 106 men (41%) treated with 3DCRT alone (p = 0.004). Compared to the Gleason score pre-RT, the Gleason score of cancers showing no RT effect was the same in 25 patients (71%), +/-1 point in 8 patients (23%), and +2 points in 2 patients (6%). The mean combined Gleason score post-RT was slightly, although significantly, higher than that pre-RT (7.29 +/- 0.71 versus 7.00 +/- 0.59, p = 0.01). Serum PSA at the time of post-3DCRT biopsy correlated with biopsy results. Prostate cancer without therapy effect was seen in only one of 43 patients (2%) with a serum PSA level < or = 1 ng/ml compared to 46 of 94 patients (49%) with a PSA level > 1 ng/ml (p = 0.0001). After 3DCRT, benign prostate glands show profound histopathologic changes and may be confused with prostate cancer. The effects of 3DCRT on prostate cancer are variable, with some cases showing profound therapy-related changes and others showing no apparent therapy effect.

Treatment changes in prostatic hyperplasia and cancer, including androgen deprivation therapy and radiotherapy

Substantial and characteristic changes occur in the microscopic appearance and immunophenotype of the hyperplastic prostate and adenocarcinoma following androgen deprivation therapy and radiotherapy. These changes are rarely seen in untreated cancer, and in the authors' opinion, the combinations of features following therapy are sufficiently distinctive to warrant recognition. Pathologists must be aware of these distinct changes because of the reliance placed on nuclear and nucleolar size in the identification of prostate cancer, particularly in small specimens and lymph node metastases.

Prevalence and distribution of prostatic intraepithelial neoplasia in salvage radical prostatectomy specimens after radiation therapy

High-grade prostatic intraepithelial neoplasia (PIN) is the most likely precursor of prostate cancer. The effect of radiation therapy (RT) on the prevalence of PIN is uncertain. We studied 86 patients who underwent salvage radical prostatectomy after irradiation failure at the Mayo Clinic. The prevalence, volume, multicentricity, spatial proximity to cancer, and architectural patterns of PIN were evaluated. High-grade PIN was identified in 53 (62%) of 86 prostatectomy specimens. Multiple architectural patterns were usually observed, including tufting in 87%, micropapillary in 66%, cribriform in 38%, and flat in 17%. The mean volume of PIN was 0.12 cm3 (range, 0.05-1.20 cm3). PIN was usually multicentric (70%), with a mean number of PIN foci of 2.5 (range, 1-10). Ninety-four percent of PIN foci were located within 2 mm of invasive cancer. There was no correlation between PIN and pathologic stage, surgical margin, tumor size, DNA ploidy, post-RT Gleason score, time interval from RT to biopsy-proven recurrence, postoperative prostate-specific antigen level, distant metastasis-free survival, or cancer-specific survival. Our examination of salvage radical prostatectomy specimens indicated that the prevalence and extent of PIN appeared to be reduced after RT compared to published studies of prostatectomies without prior RT.

Molecular analysis of multifocal prostate cancer lesions

To analyse the origin of multifocal prostate cancer lesions, radical prostatectomy specimens from 17 patients were examined. As a marker of genetic lineage, the allelotype based on 33 microsatellite loci was compared between the different tumours present in a given case. Some results provide evidence suggestive of a clonal origin of multiple tumours in a subset of the prostates. In five cases, for example, comparison of multifocal tumour lesions within a given case revealed at least two concordant changes in allelic imbalance (AI) sequence dosages at different loci. In addition, considerable heterogeneity of allelotype was found within and among tumour foci of a given case. In five of the six tumours analysed for intratumour heterogeneity, for example, more than five discordant AI changes were found in one tumour region but not in the other. Conclusions regarding the clonality of such heterogeneous lesions are difficult to draw. A high frequency of AI changes in four lesions exhibiting prostatic intraepithelial neoplasia (mean 6.5 changes per lesion, range 3-6) was found, compared with eight primary tumours present in the same cases (mean 5.8 changes per lesion, range 3-6). The interpretation of AI associated with clinically detected prostate cancer remains a highly complex issue. The fact that no clear evidence was obtained for either a clonal or a non-clonal origin of multiple lesions in a given prostate indicates that several different mechanisms are likely to operate in establishing the allelotype and that additional evidence from unique mutations or selective gene inactivation may be necessary to obtain definitive results.

Allelic imbalance in the clonal evolution of prostate carcinoma

BACKGROUND

To understand better the genetic basis of the clonal evolution of prostate carcinoma, the authors analyzed the pattern of allelic loss in 25 matched primary and metastatic prostate tumors.

METHODS

Twenty-five cases were selected from the surgical pathology files of the Mayo Clinic from patients who had undergone radical retropubic prostatectomy and bilateral lymphadenectomy between 1987-1991. All patients had regional lymph node metastases at the time of surgery. DNA samples for the analysis of allelic loss pattern were prepared from primary tumors and matched synchronous lymph node metastases by tissue microdissection. The oligonucleotide primer pairs for the microsatellite DNA markers were D8S133, D8S136, D8S137, ANK1 on chromosome 8p12-21, LPLTET on chromosome 8p22, and D17S855 (intragenic to the BRCA1 gene) on chromosome 17q21. One case was not informative at any of the loci tested and was excluded from further analysis.

RESULTS

The overall frequency of allelic imbalance was 79% in primary tumors and 88% in paired metastases. Of 24 informative cases, 14 patients (58%) showed the same pattern of allelic loss or retention in matched primary and metastatic tumors at all marker locus; discordant allelic loss was observed in the remaining 10 patients (42%). Four patients showed loss of the same allele at one or more marker loci in both primary and metastatic tumors, but discordant allelic loss was observed at other marker loci. Five patients showed allelic loss in at least one genetic marker in the metastatic tumor but not in its matched primary tumor. Five patients displayed loss of one allele at one or more marker loci in a primary tumor but not in the matched metastases. There was no significant difference in the frequency of allelic imbalance between primary and metastatic tumors at any marker analyzed (P>0.05).

CONCLUSIONS

These data suggest that different patterns of allelic deletion may be acquired during cancer progression to metastases. The differences in genetic composition between primary prostate carcinoma and its metastases may be related to intrinsic cancer heterogeneity, overall genetic instability, and clonal divergence.

Independent origin of multiple foci of prostatic intraepithelial neoplasia: comparison with matched foci of prostate carcinoma

BACKGROUND

Prostate carcinoma usually is heterogeneous and multifocal, with diverse clinical and morphologic manifestations. Understanding of the molecular basis for this heterogeneity is limited, particularly for the putative precursor, high grade prostatic intraepithelial neoplasia (PIN). In this study, the authors attempted to determine the genetic relation between multiple foci of PIN and matched foci of carcinoma, and whether they are independent in origin.

METHODS

The distribution and prevalence of allelic imbalance at 6 microsatellite polymorphic markers on chromosomes 7q, 8p, 8q, and 18q were examined in 84 microscopically excised PIN foci (mean, 1.6 foci/case) and 95 foci of prostate carcinoma (mean, 1.8 foci/case) from 52 completely embedded, mapped whole mount prostates.

RESULTS

PIN contained a lower overall proportion of allelic imbalance than matched prostate carcinoma foci for the 6 polymorphic microsatellite markers (65% vs. 82%), but this difference was not significant. The rate of allelic imbalance in PIN was similar to that in prostate carcinoma at 5 of 6 loci studied; the exception, D18S34 (18q12.2-12.3), had a significantly lower rate of allelic imbalance in PIN than in prostate carcinoma (19% vs. 52%), suggesting that genetic alterations in this chromosomal region may be important in carcinogenesis. Of 22 cases with allelic imbalance in at least 1 focus of PIN and 1 focus of prostate carcinoma, 21 informative cases (95%) showed a similar pattern of allelic imbalance at > or = 1 markers in the matched PIN and prostate carcinoma foci. Significant genetic heterogeneity was observed in both PIN and prostate carcinoma. Allelic imbalance was observed in at least 1 focus in 11 of 25 cases with multiple foci of PIN (44%) and 20 of 25 cases with multiple foci of prostate carcinoma (80%). There was no significant correlation between allelic imbalance and pathologic stage or tumor grade.

CONCLUSIONS

Our findings indicate that multiple foci of PIN arise independently within the same prostate. This observation suggests that a field effect underlies prostatic neoplasia. Multiple foci of prostate carcinoma also often arise independently, lending additional support for this hypothesis. The strong genetic similarities between PIN and prostate carcinoma strongly suggest that evolution and clonal expansion of PIN may account for the multifocal etiology of carcinomas.

Is prostatic intraepithelial neoplasia in the transition/central zone a true precursor of cancer? A long-term retrospective study in Norway

Prostatic intraepithelial neoplasia (PIN) has been considered as a precursor of prostatic cancer. Few reports have dealt with the long-term follow-up of PIN lesions, and there is still a lack of proof that PIN is a true premalignant lesion. The objective of this study was to evaluate PIN in the transition/central zone as a marker for subsequent development of prostatic cancer. The PIN status of tissue specimens from 789 men without prostate cancer was determined in 508 transurethral resections and 281 transvesical prostatic enucleations. All slides were reviewed blind and independently by two pathologists. The patients were followed for an average of 11 years, and the incidence of subsequent cancer and cause-specific survival were analysed. Thirty-six cases of clinical prostatic cancer occurred among the cohort of 789 men through follow-up. No association between the presence of PIN in the transition/central zone and subsequent cancer development was found. There was also no difference in survival related to PIN status among the subsequent cancer patients.

Digital image analysis of proliferative index: two distinct populations of high-grade prostatic intraepithelial neoplasia in close proximity to adenocarcinoma of the prostate

A considerable amount of data has been collected showing the association of high-grade prostatic intraepithelial neoplasia (HGPIN) with adenocarcinoma of the prostate, and many studies have yielded results that suggest that HGPIN is a precursor of carcinoma. A few studies have indicated that HGPIN may, in some cases, be a sequela of prostatic adenocarcinoma. We examined the proliferative indices of HGPIN, carcinoma, and benign prostatic epithelium by computer-aided counting of Ki-67-positive nuclei in 15 cases in which HGPIN and carcinoma were in close proximity. There were 13 radical prostatectomy specimens with prostate cancer and two cystoprostatectomy specimens with both transitional cell carcinoma and prostatic adenocarcinoma. First, we showed the accuracy of the computer-aided counting method compared with direct counting through the binoculars of the microscope. Then proliferative activity was assessed for each case by picking the two areas of carcinoma, the two areas of HGPIN, and the one area of benign epithelium with the greatest density of carcinomatous, dysplastic, and benign Ki-67-positive nuclei, respectively. The total number of nuclei and the number of positive nuclei were counted. Basal cells were not counted. The mean proliferative index was higher for cancer (caindex, average 0.054) than for HGPIN (pinindex, average 0.048) (P < .05). We found that the 15 cases fell into two distinct groups. The average ratio of pinindex to caindex (pinindex/caindex) was lower in group 1 (0.72) than in group 2 (1.54) (P=.17), and when the results were corrected for the nonzero gamma-intercepts of the regression lines of pinindex versus caindex, the ranges were widely separated, and the difference between the means was statistically significant (0.15 v 0.62; P < .0001). A greater subjective similarity between the nuclear features in the HGPIN and those of the corresponding carcinoma was noted for the cases in group 2. The average value of bngnindx was 0.014. The value of bngnindx did not correlate with either caindex or pinindex. We conclude that there may be two types of lesions with the morphological appearance of HGPIN and that they may have different relationships to carcinoma. Computer-aided counting of digitized microscopic images is both labor-saving and as accurate as enumeration directly through the binoculars of the microscope.

Evidence of independent origin of multiple tumors from patients with prostate cancer

BACKGROUND

In men with prostate cancer, the gland usually contains two or more widely separate tumors. A critical issue of prostatic carcinogenesis is whether these multiple tumors are independent in origin. Molecular analysis of microsatellite (i.e., highly repeated, short nucleotide sequences) alterations in the DNA from separate tumors in the same prostate can be used to determine whether or not these separate tumors arise independently.

METHODS

Four microsatellite polymorphic markers (D8S133, D8S136, and D8S137, for a putative tumor suppressor gene on chromosome 8p, and D17S855, for the BRCA1 gene on chromosome 17q) were used to examine the pattern of allelic loss in prostate cancer from 19 patients who had two or more distantly separate tumors (i.e., located on contralateral sides or separated by at least half the anterior-posterior diameter of the prostate). Forty distantly separate tumors were microdissected, DNA samples were prepared from formalin-fixed, paraffin-embedded wholemount prostate tissue section, and the overall frequencies of loss of heterozygosity at the four loci were determined.

RESULTS

The pattern of allelic loss was compatible with independent tumor origin in 15 of 18 informative cases. A random discordant pattern of allelic deletion was observed in distantly separate tumors, whereas the same allele was consistently lost in cells from different regions of the same tumor. For three patients, the results were compatible with either intraglandular dissemination or independent origin of prostate cancer.

CONCLUSIONS

Our data suggest that multiple tumors in some patients with prostate cancer have independent origin.

Prostatic intraepithelial neoplasia does not appear to raise serum prostate-specific antigen concentration

OBJECTIVES

Conflicting findings have been reported regarding the relationship between prostatic intraepithelial neoplasia (PIN) and serum prostate-specific antigen (PSA) concentration. This study evaluates whether high-grade PIN significantly raises serum PSA concentration.

METHODS

We evaluated 194 totally embedded whole-mounted radical prostatectomy specimens removed for clinically localized prostate cancer. No patient received preoperative therapy. In each specimen, the volume of high-grade PIN and carcinoma was calculated using the grid-counting method. Serum PSA concentration was determined prior to surgery. Cancer volume, gland weight, Gleason score, extraprostatic extension, and PIN volume were then compared according to serum PSA concentration and PSA density.

RESULTS

Of the 194 patients, 170 (88%) had high-grade PIN-associated cancer and 24 (12%) had PIN-free cancer within the specimen. PIN volume ranged from 0 to 8.1 cc (mean, 1.3) and cancer volume ranged from 0 to 56.9 cc (mean, 9.1). In a subset of 93 patients with small cancers (less than 6.0 cc), PIN volume ranged from 0 to 6.1 (mean, 0.83) and did not correlate with serum PSA concentration or PSA density (P = 0.80 and P = 0.69, respectively). In the entire study group, PIN volume did not correlate with PSA density (P = 0.17), but did correlate with serum PSA concentration (P = 0.005). Using multiple regression analysis, adjusting for cancer volume, gland weight, Gleason score, and extraprostatic extension, log PIN volume did not contribute to log serum PSA concentration (regression coefficient -0.108; P = 0.51) or log PSA density (regression coefficient -0.104; P = 0.56) in small cancers (less than 6.0 cc). In the entire study group, log PIN volume did not contribute to log serum PSA concentration (regression coefficient -0.182; P = 0.05) or log PSA density (regression coefficient -0.202; P = 0.56).

CONCLUSIONS

Our data indicate that high-grade PIN does not significantly contribute to serum PSA concentration. We suggest that patients with elevated serum PSA concentration found to have high-grade PIN on transrectal biopsy should not have their elevated serum PSA concentration attributed to high-grade PIN.