Presence Of Prostatic Intraepithelial Neoplasia Research Articles

Clinicopathological study of associated lesions in benign prostatic hyperplasia and prostatic adenocarcinoma in surgical biopsy specimens

Background: Benign prostatic hyperplasia (BPH) and prostatic adenocarcinoma are two principal conditions of prostate among elderly men. In spite of significant advances in early detection of prostatic carcinoma by transrectal ultrasound and serum prostatic specific antigen, major diagnostic problem exists in the diagnosis between adenocarcinoma and benign small acinar proliferations. This study aims to study the association of hyperplastic, metaplastic, inflammatory and premalignant lesions in prostate specimens over a period of 5 years and to analyze histological types and significance of associated lesions in BPH and different grades of prostatic adenocarcinoma. Methods: Prostate specimens over a period of 5 years were analyzed for gross and microscopic findings. All prostatic adenocarcinoma cases are graded using Gleason grading system and analyzed for the presence of prostatic intraepithelial neoplasia (PIN) and atypical adenomatous hyperplasia (AAH) and other associated lesions. Results: BPH constitute the commonest lesion (92.1%), followed by Adenocarcinoma (7.9%). All cases of focal acinar/cystic atrophy showed increase in trend towards increasing age. Among hyperplastic lesions, basal cell hyperplasia was found to be the most common epithelial lesion. Among premalignant lesions, PIN was found most commonly in association with prostatic adenocarcinoma. In concurrence with literature it was observed that high-grade PIN was the most common premalignant lesion associated with prostatic adenocarcinoma (51.2%) than AAH. Conclusion: LGPIN, HGPIN and chronic prostatitis were found to be associated with adenocarcinomas (statistically significant with P 0.05) when comparison is done between low- and high-grade adenocarcinoma. DOI:10.21276/APALM.1608

THE ROLE OF NEW MARKERS IN THE DIFFERENTIAL DIAGNOSIS OF PROSTATE CANCER

AIM: to determine the significance of [-2]proPSA and prostate health index for the diagnostics of prostate diseases in patients with PSA level in blood plasma less than 4 ng/ml. PATIENTS AND METHODS: 148 men were examined in the urology clinic of Pavlov First Saint Petersburg State Medical University for the exclusion of prostate cancer (PCa). The inclusion criteria were: the level of total PSA in blood plasma less than 4 ng/ml, the presence of changes in the prostate during digital rectal examination, the detection of hypoechoic sites according to transabdominal ultrasound examination of the prostate or a decrease in the ratio of free and total PSA in blood plasma less than 15%. For all the patients the level of [-2]proPSA was assessed, its percentage to total PSA and the prostate health index were calculated. Based on the results of the biopsy, all patients were divided into 3 groups. Patients with histopathomorphologically verified benign prostatic hyperplasia (BPH) were included in the first group (83 patients), in the second group (14 patients) - with prostatic intraepithelial neoplasia (PIN), in the third (51 patients) - patients who had focal atypia and/or adenocarcinoma of the prostate. Clinical and laboratory parameters were compared between the abovementioned groups. RESULTS: Prostate health index was found to be the most significant factor of difference comparing patients with BPH and PCa, as well as in the presence of PIN and PCa (p<0.001 for both), while a statistically significant difference in this indicator was not obtained comparing BPH and PIN patients. CONCLUSION: Prostate health index showed the greatest prognostic value in the diagnostics of prostate diseases in patients with PSA level in blood plasma less than 4 ng/ml.

Obesity and Future Prostate Cancer Risk among Men after an Initial Benign Biopsy of the Prostate

In general population studies, obesity has been associated with risk of high-grade prostate cancer, but little is known about obesity and future prostate cancer risk among men with an initial benign biopsy of the prostate; a high-risk population. Within a cohort of 6,692 men followed up after a biopsy or transurethral resection of the prostate (TURP) with benign findings, a nested case-control study was conducted of 494 prostate cancer cases and controls matched on age, race, follow-up duration, biopsy versus TURP and date of procedure. Body mass index at the time of the initial procedure was abstracted from medical records, and initial biopsy specimens were reviewed for the presence of prostatic intraepithelial neoplasia (PIN). Obesity was associated with the presence of PIN in the initial benign specimen [OR = 2.15; 95% confidence interval (CI) 1.13-4.11]. After adjustment for the matching variables, family history of prostate cancer, prostate-specific antigen (PSA) levels at the initial procedure, the number of PSA tests and digital rectal examinations during follow-up, obesity (OR = 1.57; 95% CI, 1.07-2.30) at the time of the initial procedure was associated with prostate cancer incidence during follow-up. Risk associated with obesity was confined to cases with follow-up less than 1,538 days, the median duration of follow-up among cases (OR = 1.95; 95% CI, 1.09-3.48). Obesity is associated with the presence of PIN in benign specimens and with future prostate cancer risk after an initial benign finding. Obesity may be a factor to consider when planning clinical follow-up after a benign biopsy.

Prostate Cancer and Prostatic Intraepithelial Neoplasia: True, True, and Unrelated?

Prostate Cancer and Prostatic Intraepithelial Neoplasia: True, True, and Unrelated?

High-level expression of forkhead-box protein A1 in metastatic prostate cancer

Expression of forkhead-box protein A1 (FOXA1), a transcription factor important for normal development of the prostate gland, is thought to be controlled by steroid hormones and GATA3. The aim of this study was to investigate the expression and potential role of FOXA1 and GATA3 transcription factors as prognostic factors in prostate cancer. Expression of FOXA1, GATA3 and androgen receptor (AR) was retrospectively analysed by immunohistochemistry in a series of 80 primary tumours and 28 metastatic prostate cancers, including 15 matched paired samples. Nuclear AR expression did not significantly differ between primary and metastatic tumours. High-level nuclear FOXA1 expression was seen in 19% of primary and 89% of metastatic tumours (P < 0.0001). FOXA1 expression correlated positively with tumour size, extraprostatic extension, angiolymphatic invasion, AR and lymph node metastases at diagnosis, but did not correlate with age, T stage, Gleason score, presence of prostatic intraepithelial neoplasia or multifocality, seminal vesicle or perineural invasion, or surgical excision margin status. Expression of GATA3 was not seen in either normal epithelium or tumour. Our preliminary analyses suggest that high-level FOXA1 expression is associated with the development of metastatic prostate cancer. If these data are confirmed, FOXA1 expression could be used to classify patients at higher risk for metastases.

Outcome for Repeated Biopsy of the Prostate

We studied the relationships between the outcome in the last follow-up prostate biopsy specimen and serum prostate-specific antigen (PSA), prostatic intraepithelial neoplasia (PIN), and atypical small acinar proliferations (ASAPs) at the occasion of the initial biopsy in 244 cases in which the initial specimen was negative for tumor and at least 1 follow-up biopsy was done. PSA levels and ASAPs were significantly associated with cancer in the follow-up biopsy specimen (<P < .005; logistic regression analysis); however, the presence of PIN in the initial biopsy specimen did not relate to cancer in the follow-up specimen (P > .1). Thus, the probability that a follow-up biopsy demonstrates cancer depends on PSA and ASAPs, and even when ASAPs are present, serum PSA exerts an influence. For example, low PSA values, 5 ng/mL (5 mug/L) or less, are associated with low probabilities of a positive follow-up biopsy result, even when ASAPs were present in the first biopsy specimen. For higher PSA values, the presence of ASAPs dramatically increases the probability of a positive follow-up biopsy result compared with cases with no atypia or PIN in the first biopsy specimen.

Eradication of prostatic high grade intraepithelial neoplasia: Hypothesis and clinical proof

1534 Background: Recently normal prostate tissue has been found to contain a high concentration of retinoid X receptors (RXRs), they are found in the highest concentrations in ectodermal tissue. Loss of these receptors is associated with prostatic intraepithelial neoplasia (PIN), and can be present in patients with a normal PSA. There are 115,000 cases of high grade PIN discovered yearly in the United States.The drug bexarotene used to treat cutaneous T cell lymphoma (CTCL). The compound is not a true retinoid in structure, perusal of the structure reveals two aromatic rings one of which contains a carboxy group which would make one anticipate strong hydrogen bonding when it undergoes binding to the RXRs as if it were a retinoid, resulting in “up regulation” of the tissue with increase in differentiation to normal tissue. Based upon this it was felt that it would be fruitful to try bexarotene in High Grade PIN. Method: The diagnosis was based upon 12 biopsies which were done in conjunction with ultrasound localization of the biopsy site, with careful recording of there anatomical position. The patient was started on bexarotene 225 mg per day. The drug was given as a single dose once daily; this dose is 40% of the dose normally used to treat CTCL. The drug was administered for 30 doses During the period of therapy the patient was on Atorvastin T4 total was within the normal range. Results: Four weeks following the last dose of bexarotene the prostate was rebiopsied with 12 biopsies taken. Six of the biopsies were taken from the putative area, the rest in an enlarging target like pattern. The repeat biopsy was negative for the presence of PIN. 14 months later 12 more biopsies were obtained using the same technique, these repeat biopsies were also found to be negative; ie. 24 negative biopsies over 14 months. It is unlikely that the previously involved area was missed. Conclusion: If a mechanism of action were to be formulated, the induction of and increase in RXRs in normal prostate cells would be reasonable. Cells that undergo the formation of PIN, strong hydrogen bonding and inability of those cells to produce more receptors could result in apoptosis. Undoubtedly further study is required to evaluate the effect of this drug in high grade PIN. No significant financial relationships to disclose.

Clinical predictors of gleason score upgrading

Brachytherapy, active surveillance, and watchful waiting are increasingly being offered to men with low-risk prostate cancer. However, many of these men harbor undetected high-grade disease (Gleason pattern > or =4). The ability to identify those individuals with occult high-grade disease may help guide treatment decisions in this patient cohort. The authors identified 175 cases of low-risk prostate cancer treated with radical prostatectomy. By using logistic regression analysis, 11 a priori-defined preoperative risk factors were evaluated for their ability to predict upgrading from Gleason 6 at biopsy to Gleason > or =7 at radical prostatectomy. An internally validated nomogram using all clinical variables was subsequently created to help physicians identify patients who had undetected high-grade disease. A total of 60 (34%) patients were upgraded to high-grade disease. On multivariate analyses, both prostate-specific antigen (PSA) level (P = .02) and the level of pathologist expertise (P = .007) were predictive of upgrading. The predictive nomogram contained these variables plus age, digital rectal examination, transrectal ultrasound results, biopsy scheme applied (sextant vs extended), presence of prostatic intraepithelial neoplasia, prostate gland volume, and percentage of cancer in the biopsy. The nomogram provided acceptable discrimination (C statistic 0.71). The authors identified significant predictors of upgrading for patients diagnosed with low-risk prostate cancer. A nomogram based on these study findings could help physicians further risk-stratify patients with low-risk prostate cancer before embarking on treatment. Caution should be exercised in recommending nonradical therapy to individuals with a high probability of undetected high-grade disease.

Functional heterogeneity of prostatic intra-epithelial neoplasia: Length of hormonal therapy influences response

4648 Background: Prostatic intraepithelial neoplasia (PIN) is a premalignant lesion of the prostate etiologically linked to prostate cancer. While androgen deprivation therapy (ADT) has been used to reduce prostate cancer, there are controversial data regarding the effect of ADT on PIN. We hypothesized that PIN is a heterogeneous entity with respect to hormone responsiveness, that this may explain aspects of the heterogeneity in the natural history of this disease, and have used the clinical model of ADT followed by radical prostatectomy as a test of this hypothesis. Methods: We performed a retrospective study on a cohort of patients who underwent prostatectomy with biopsy proven prostate cancer. Study patients were those who must have received at least 3 months of ADT at the discretion of their surgeons. Patients from the same cohort who did not undergo ADT were used as controls. Patients were randomly selected from the database and their pathology slides were reviewed by a blinded pathologist looking for presence of PIN with an independent observer. Fisher’s exact test was used to compare the proportions of subjects who had residual PIN in the study group and the control group. Exact logistic regression was used to evaluate the duration of ADT in PIN regression. Results: Eighteen patients initially diagnosed with PIN who did not receive hormonal therapy were identified; 28 patients with PIN who underwent hormonal therapy were also studied. All patients who did not receive hormonal therapy had residual PIN whereas 7 of 28 patients undergoing ADT had no residual PIN (p = 0.043). Evaluation of hormonal therapy between responders and non-responders showed statistically significant association between PIN regression and hormone therapy duration (p &lt; 0.001). However PIN response to ADT was not uniform as 16% of patients with ADT longer than 6 months had residual PIN, suggesting variable sensitivity of PIN to ADT. Conclusions: Our results demonstrate that ADT does cause PIN regression, and that there is heterogeneity in this effect with respect to hormonal duration. We propose for future prospective, multi-centered, randomized trials in which ADT impact on PIN is characterized further. No significant financial relationships to disclose.

Elevated Expression of Angiogenin in Prostate Cancer and Its Precursors

Angiogenin is a polypeptide involved in the formation and establishment of new blood vessels necessary for growth and metastasis of numerous malignant neoplasms, including prostatic adenocarcinoma. Antiangiogenin therapy inhibits the establishment, growth, and metastasis of prostatic adenocarcinoma in animal studies. In this study, we have investigated the expression of angiogenin in prostatic adenocarcinoma, high-grade prostatic intraepithelial neoplasia, and adjacent benign prostatic epithelium in a large cohort of prostatectomy specimens. We have studied the expression of angiogenin by immunohistochemistry in prostatic adenocarcinoma, high-grade prostatic intraepithelial neoplasia, and adjacent benign prostatic tissue in 107 human total prostatectomy specimens. The percentage of cells staining positively for angiogenin in benign prostatic glandular epithelium (mean = 17%) was significantly less than for high-grade prostatic intraepithelial neoplasia (mean = 58%, P < 0.001) and prostatic adenocarcinoma (mean = 60%, P < 0.001). Compared with adjacent benign prostatic epithelium, the staining intensity was significantly greater in high-grade prostatic intraepithelial neoplasia (P < 0.001) and prostatic adenocarcinoma (P < 0.001). Furthermore, staining intensity has significantly stronger in prostatic adenocarcinoma versus high-grade prostatic intraepithelial neoplasia (P = 0.0023). However, there was no correlation of angiogenin expression with various clinical and pathologic variables examined, including age at surgery, Gleason scores, pathologic stage, tumor extent, angiolymphatic invasion, extraprostatic extension, seminal vesical invasion, lymph node metastasis, surgical margin status, presence of prostatic intraepithelial neoplasia, and perineural invasion. Angiogenin expression in prostatic tissue increases as prostatic epithelial cells evolve from a benign to an invasive phenotype. The increasing expression of prostatic adenocarcinoma in the progression from benign prostate to high-grade prostatic intraepithelial neoplasia and ultimately to prostatic adenocarcinoma are consistent with previous studies showing the influential role that angiogenin plays in the growth, invasion, and metastasis of prostatic adenocarcinoma and many other malignant tumors.

Systematic transperineal ultrasound-guided template biopsy of the prostate: Three-year experience

Objectives To review the technique of transperineal saturation prostate biopsy and to update our results on patients at high risk of prostate cancer. Methods A total of 210 men who met the study inclusion criteria underwent systematic transperineal ultrasound-guided template biopsy of the prostate. All patients had previously undergone at least one set of transrectal prostate biopsies and 170 (81%) had undergone two or more. The mean number of prostate cores obtained before the template biopsy was 17.4. A mean of 21.2 cores (range 12 to 41) were obtained at the template biopsy, depending on prostate size. The study inclusion criteria included prostate-specific antigen level of 10 ng/mL or greater, prostate-specific antigen velocity of 0.75 ng/mL per year or greater, or the presence of prostatic intraepithelial neoplasia and/or atypical small cell acinar proliferation on the previous biopsy. Results Adenocarcinoma was detected in 78 men (37%). Cancer was detected in the transition zone in 60 (77%) of these 78 men, including 36 (46%) in whom cancer was identified uniquely in the transition zone. Gleason sum 6 (range 3 to 9) was the most common biopsy grade. Thirty patients underwent radical prostatectomy, and 27 (90%) had pathologic Stage pT2 disease as the final pathologic stage. Complications from biopsy were limited to postprocedural urinary retention in 11% of patients. Conclusions A systematic transperineal template biopsy provides uniform sampling of the entire prostate. This technique appears to enhance the identification of transition zone cancers not detected by previous transrectal prostate biopsy in patients at high risk of prostate adenocarcinoma.

Predictors of prostate cancer on repeat transrectal ultrasound-guided systematic prostate biopsy.

We analyzed the outcome of repeated transrectal ultrasound (TRUS)-guided systematic prostate biopsy in Japanese men whose clinical findings were suspected of prostate cancer after previous negative biopsies. Between January 1993 and March 2002, 1045 patients underwent TRUS-guided prostate biopsy. Among them, 104 patients underwent repeat biopsy due to indications of persistent elevated serum prostate-specific antigen (PSA), abnormal digital rectal examination (DRE) or TRUS, increased PSA velocity, and/or previous suspicious biopsy findings. Several clinicopathological factors were evaluated for their ability to predict the detection of prostate cancer on repeat biopsy. Prostate cancer was detected in 22 of 104 patients (21.2%) who underwent repeat biopsies. PSA concentration and PSA density at both the initial and repeat biopsies, and PSA velocity in men with positive repeat biopsy were significantly greater than those in men with negative repeat biopsy. The incidence of abnormal findings in DRE and TRUS at initial biopsy in men with positive repeat biopsy was also significantly higher than that in men with negative repeat biopsy. However, neither the presence of prostatic intraepithelial neoplasia nor number of biopsy cores at initial biopsy had a significant association with the results of the repeat biopsy. Furthermore, multivariate analysis revealed that PSA and PSA density at both the initial and repeat biopsies, PSA velocity, and DRE and TRUS findings at initial biopsy were independent predictors of malignant disease on repeat biopsy. Despite an initial negative biopsy, repeat TRUS-guided biopsy should be carried out to exclude prostate cancer in cases of suspicious clinical findings, such as elevated PSA or PSA-related parameters, or abnormal findings of DRE or TRUS.

Clinical Management of Premalignant Lesions of the Prostate

AbstractThe presence of high-grade prostatic intraepithelial neoplasia (PIN) in a prostate biopsy is a considerable risk factor for the presence of prostate cancer, with up to 73% of patients having cancer on rebiopsy. The risk is related to the clinical setting (screening vs urological practice) and patient factors such as prostatic serum antigen (PSA) and findings on digital rectal examination (DRE). Thus, high-grade PIN has serious clinical implications. The aim of this paper is to propose practical guidelines for the clinical management of PIN. Based on current knowledge we recommend that: Only patients considered for curative treatment of prostate cancer be further investigated for a PIN biopsy finding. A palpable nodule or tumor-suspicious transrectal ultrasonography (TRUS) finding, in conjunction with a finding of high-grade PIN on prostate biopsy, should prompt rebiopsy. An elevated PSA level or an elevated PSA density should also warrant repeat biopsy, as the most likely cause of PSA elevation is concomitant prostate cancer. The presence of high-grade PIN on biopsy without concomitant prostate cancer in patients suitable for curative treatment, notwithstanding normal DRE, TRUS or PSA, should prompt repeat biopsies, as the association with prostate cancer is significant. The presence of PIN alone on biopsy does not warrant treatment, as a substantial number of rebiopsies yield only PIN.

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.

Clinical significance of high-grade prostatic intraepithelial neoplasia in transurethral resection specimens

High-grade prostatic intraepithelial neoplasia (PIN) is the most likely precursor of invasive prostatic adenocarcinoma. The incidence and clinical significance of this lesion have not been previously defined in specimens from transurethral resections of the prostate (TURP). To determine the frequency of PIN in TURP specimens and its relationship with adenocarcinoma, we reviewed 698 resections performed at Mayo Clinic between 1989 and 1990. A mean of 6 slides was analyzed for each case (range 1 to 36). The presence, extent, and architectural pattern of PIN were recorded. The results were correlated with many clinical and pathologic features, including patient age, Gleason score, stage, serum prostate-specific antigen (PSA) concentration, and patient follow-up. In a 1:2 nested matching case-control study, we compared the outcome of cases with PIN alone with that of the control group. Each patient with PIN alone (16 patients) was matched randomly with 2 patients with benign prostatic hyperplasia (BPH) alone (32 patients) according to age (+/- 5 years) and serum PSA concentration (+/- 1 ng/mL). Of 698 TURP specimens, 570 (81.7%) contained BPH and 128 (18.3%) contained adenocarcinoma and BPH. High-grade PIN was identified in 29 cases (4.2%), including 16 (2.8%) of those with BPH and 13 (10.2%) of those with cancer and BPH. Follow-up revealed adenocarcinoma in 3 of 14 patients (21.4%) with PIN and BPH only after 3, 5, and 7 years, respectively; mean follow-up for the 14 patients was 6 years (range 4 to 7 years), and none of the patients died of prostate cancer. Conversely, none of the patients (0%) without PIN in TURP specimens in the case-control study had subsequent adenocarcinoma. The overall incidence of PIN in TURP specimens was 4.2%, including 2.8% without cancer and 10.2% with coexistent cancer. Prostatic adenocarcinoma was diagnosed within 7 years in 21.4% of patients with PIN in TURP specimen. Conversely, none of those without PIN matched for age and serum PSA had adenocarcinoma at follow-up. These results indicate that high-grade PIN is uncommon in TURP specimens and, when found, indicates a significant risk of cancer. The presence of PIN in TURP specimens should be reported by the pathologist; in addition, the entire specimen should be submitted for histologic examination to exclude carcinoma.

The alpha 6 beta 1 and alpha 6 beta 4 integrins in human prostate cancer progression.

Prostatic secretions are formed by glands composed of basal and luminal cells and surrounded by a basal lamina. The normal basal cells express several integrins (extracellular matrix receptors) including alpha 2, 3, 4, 5, 6, v, beta 1 and beta 4. These integrin units are polarized at the base of the cells adjacent to the basal lamina. The integrin alpha 6 beta 4 is associated with hemidesmosomal-like structures. The natural history of prostate cancer involves the presence of prostatic intraepithelial neoplasia (PIN) lesions (considered precursor lesions), carcinoma in situ and invasive carcinoma. Hemidesmosomal proteins and the alpha 3 beta 1 and alpha 6 beta 1 integrins (laminin receptors) are retained in the early PIN lesions. Expression of the integrins alpha 2, alpha 4, alpha 5, alpha v and beta 4 is lost in carcinoma. The alpha 3 beta 1 and alpha 6 beta 1 integrins remain associated with invasive carcinoma, the latter being predominant. Integrin expression in carcinoma is diffuse in the plasma membrane and not restricted to the basal aspects of the cell. The alpha 6 beta 1 integrin is fully functional as judged by an ability to adhere to laminin and contains the wild type alpha 6A cytoplasmic signaling domain. The alpha 6 beta 1 integrin is a leading candidate for conferring the invasive phenotype in prostatic carcinoma. Tumor cells with high expression of alpha 6 integrin are more invasive when tested in a SCID mouse model system. Following intraperitoneal injection, the human tumor cells invade the mouse diaphragm and move through the muscle on the surface of the laminin coated muscle cells. Our current working hypothesis is that the production of alpha 6 beta 1 and laminin in human tumor cells contributes to the invasive phenotype. Invasion could occur on the surfaces of laminin coated structures such as the nerves, blood vessels or muscle and account for the known patterns of human prostate tumor progression. Blockage of the expression or function of alpha 6 beta 1 or laminin or preventing the loss of beta 4 would be essential steps in confining the carcinoma to the prostate gland where conventional treatment has already proven effective.

Gene expression profiling reveals overexpression of TSPAN13 in prostate cancer

Prostate cancer is one of the most frequent malignancies in the Western world. The identification of additional molecular markers is needed to refine the diagnosis of prostate cancer and to develop more effective therapies. In order to identify molecular abnormalities involved in prostate cancer progression, we performed gene expression analysis of prostate cancer samples compared to matched normal tissue from the same patient using a cancer-related microarray. Amplified RNA was hybridized to a cDNA microarray containing 6386 genes and tissue microarrays were used to study protein expression levels. Using significance analysis of microarrays, we identified >1300 genes differentially expressed in prostate cancer compared to normal tissue. Forty-two of these genes were highly upregulated in prostate cancer while 169 were highly repressed. We found that the gene coding for tspan13 was upregulated >2-fold in 75% of the samples analyzed. Immunohistochemistry analysis of prostate cancer tissue microarrays showed that tspan13 is overexpressed in 80% of prostate cancer samples analyzed. We found that tspan13 expression inversely correlates with Gleason score (p=0.01) and PSA preoperative levels (p=0.11) and directly correlates with presence of prostatic intraepithelial neoplasia in tumor tissue (p=0.04). Moreover, we detected tspan13 expression in low-grade prostatic intraepithelial neoplasia. Thus, our results show that tspan13 is overexpressed in prostate cancer and its expression correlates with factors of favourable outcome. Therefore we suggest that tspan13 may have an important role in the progression of prostate cancer.