Clinical and pathologic tumor characteristics of prostate cancer as a function of the number of biopsy cores: a retrospective study.

OBJECTIVES: Many men with negative prostate biopsies and persistently elevated serum total prostate-specific antigen (tPSA) values will have cancer detected on a repeated biopsy. An important issue is whether the cancer would have been detected on the initial biopsy had more biopsy samples been obtained. The objective of our study was to retrospectively characterize the clinical and pathologic tumor features associated with men who underwent sextant core biopsies compared with men who needed more than six core biopsies during one or more biopsy sessions to detect prostate cancer. Transrectal ultrasound (TRUS)-estimated prostatic volume was evaluated to determine whether the number of biopsy cores needed for prostate cancer detection was influenced by gland size. METHODS: We retrospectively evaluated the number of biopsy core samples obtained in 185 men (mean age 63+/-6 years) enrolled in our PSA-based screening study for prostate cancer who were found to have prostate cancer and elected radical prostatectomy as treatment. Correlation coefficients were calculated and univariate analyses were performed to evaluate clinical (age, tPSA, TRUS volume, PSA density) and pathologic (Gleason score, pathologic weight, organ confinement, "possibly harmless" cancer) characteristics associated with men who required more biopsy cores to detect the cancer. RESULTS: Of the 185 men, 103 (56%) had 6 or fewer total biopsy cores taken and 82 (44%) had more than 6 cores (44 [24%] of 185 had 7 to 12 cores and 38 [20%] of 185 had 13 or more cores). There was a positive correlation between age, serum tPSA, TRUS-determined prostate volume, and pathologic specimen weight and an increasing number of total cores (all P values < 0.05). The number of biopsy cores was not associated with PSA density, Gleason score, cancer volume, organ confinement, or "possibly harmless" cancers (all P values > 0.05). Men with a TRUS volume 30 cc or less (46%) required a mean of 8 total cores to detect the cancer compared with a mean of 11 cores (P = 0.003) in men with a TRUS volume greater than 30 cc (54%). A greater percentage of men with a TRUS prostate volume greater than 30 cc compared with men whose volume was 30 cc or less would have had their cancer missed with only a six-core biopsy (64% versus 46%, P = 0.01). CONCLUSIONS: Sextant core biopsies may be inadequate to detect prostate cancer in some men. These data support the performance of more than six core biopsies to detect clinical prostate cancer. A prospective trial using TRUS-determined prostate volume to determine the number of cores to take is needed to accurately assess this issue.

Predicting the pathology results of radical prostatectomy from preoperative information: a validation study.

BACKGROUND: There are now over 13 published models for predicting the outcomes of radical prostatectomy using preoperative information. Because their ability to predict the pathology of the prostatectomy is key in deciding who benefits the most from this surgery, it is important to know how well these models work for new data. METHODS: The patients in this study were 100 men diagnosed with prostate carcinoma in the prostate specific antigen (PSA)-based screening program at Washington University Medical Center. To test the models, the authors used preoperative information and the published algorithms to predict postoperative pathology outcomes. Statistical methods included plots of predicted probability against observed probability, boxplots of predicted probability against observed outcomes, logistic regression, and linear regression. RESULTS: Although none of the published models predicted the outcomes of radical prostatectomy perfectly, those that predicted tumor volume performed best, and in general those that were multivariate also performed best. Nevertheless, the ability of any of these models to discriminate binary outcomes was not very great. CONCLUSIONS: The results of this study suggest that preoperative variables based on serum PSA and the results of needle biopsies can be used in multivariate models to predict tumor volume, but these models need to be improved. Predicting locally advanced tumor stage is likely to be more difficult and may require information beyond what needle biopsies can provide.

Minimal carcinoma in prostate needle biopsy specimens: diagnostic features and radical prostatectomy follow-up.

Prostate cancer screening and early detection efforts have resulted in the identification of smaller volume carcinomas of the prostate. We evaluated the diagnostic features of minimal (< 1 mm) carcinoma in sextant needle biopsy specimens of the prostate and in follow-up analyzed the features of the corresponding carcinomas in the whole gland. We reviewed specimens from 50 consecutive patients who had minimal carcinoma in needle biopsy tissue and who had undergone radical prostatectomy. Histologic grade, tumor size, pathologic stage, and margin status of the 50 carcinomas in the whole gland in which the carcinoma size was minimal in the sextant needle biopsy specimen were compared with those of 50 carcinomas in the whole gland in which carcinoma size was greater than 1 mm in the needle biopsy specimen. The most common morphologic features of these minimal carcinomas were nucleomegaly (96%), infiltrative growth pattern (88%), intraluminal secretions (78%), prominent nucleoli (64%), associated high-grade prostatic intraepithelial neoplasia (40%), amphophilic cytoplasm (36%), hyperchromatic nuclei (30%), and intraluminal crystalloids (22%). Perineural invasion (2%), collagenous micronodules (2%) and mitotic figures (2%) were uncommon. The mean tumor volume in the whole gland of carcinomas corresponding to minimal carcinoma in a needle biopsy specimen was significantly smaller (P=.029) at 1.1 mL than it was in carcinomas with tumor greater than 1 mm in the needle biopsy specimen at 1.6 mL, but other pathologic features of carcinoma in the whole gland were not significantly different. In conclusion, a constellation of morphologic attributes is important for establishment of a diagnosis of minimal carcinoma of the prostate in needle biopsy specimen. Most (82%) of the corresponding prostate cancers in the whole gland were pathologically significant.

Percentage of free serum prostate-specific antigen as a predictor of pathologic features of prostate cancer in a screening population.

OBJECTIVES: Measurement of the percentage of free prostate-specific antigen (%FPSA) in serum can improve the specificity of prostate cancer screening. We evaluated the ability of %FPSA to predict pathologic features of screen-detected clinically localized prostate cancer. METHODS: We evaluated the correlation between %FPSA in serum before cancer diagnosis and the pathologic features of the cancers detected in 108 men with clinically localized prostate cancer who were treated with radical prostatectomy and for whom complete embedding of the radical prostatectomy specimen was performed. Ninety-seven men (90%) had a previous negative screening evaluation before prostate cancer was detected. RESULTS: There was a negative correlation of %FPSA with penetration of cancer through the prostatic capsule, cancerous surgical margins, Gleason score, percentage of cancer in the gland, and tumor volume (r = -0.2 to -0.4). After controlling for other preoperative predictors, %FPSA predicted capsular penetration (adjusted odds ratio [OR] 1.6, 95% confidence interval [CI] 1.1 to 2.4, for each 5% decrease in %FPSA) and cancer volume 0.5 cc or greater (adjusted OR 1.6, 95% CI 1.1 to 2.3). Preoperative %FPSA also predicted possibly harmless cancer (OR 1.5, 95% CI 1.1 to 2.2, for each 5% increase in %FPSA). CONCLUSIONS: In a select group of men for whom cancer was detected early via screening, a lower %FPSA in serum suggests a potentially more threatening cancer. This information may aid patients and clinicians in making more informed decisions about the management of prostate cancer, such as selecting patients for watchful waiting. However, more research is needed to determine the performance characteristics of %FPSA in clinical practice.

A clinical-care pathway for decreasing hospital stay after radical prostatectomy.

OBJECTIVES: To evaluate the use of a clinical-care pathway that decreased the stay in hospital after radical retropubic prostatectomy from 3 to 2 days, assessing the costs and quality of care. PATIENTS AND METHODS: Forty-four consecutive men who underwent radical retropubic prostatectomy were evaluated prospectively. The first 22 men were hospitalized under the standard 3-day clinical-care pathway in use at our institution. This pathway was evaluated, shortened to construct a 2-day pathway, and a second group of 22 consecutive men hospitalized under the new pathway. Both groups were evaluated and compared 6 weeks post-operatively. RESULTS: The mean (SD) hospital stay was 2.1 (0.3) days for men in the 2-day and 2.9 (0.4) days for men in the 3-day pathway (P < 0.001). The mean (SD) hospital cost was $8468 (801) in the 2-day and $8806 (630) in the 3-day pathway (P=0.13). None of the men in the 2-day and one of 22 men in the 3-day pathway experienced a major complication (P=0.31). Two of 22 men in the 2-day and one of 22 in the 3-day pathway exceeded the expected stay by one day (P=0.55). CONCLUSION: The hospital stay after radical retropubic prostatectomy can be safely shortened from 3 to 2 days for most men. However, the shorter hospital stay does not result in significant cost savings. The shorter stay does not appear to compromise quality of care. Proper patient education and careful pre- and post-operative supervision are necessary for a successful outcome.

The significance of intraluminal crystalloids in benign prostatic glands on needle biopsy.

Based on data from autopsy, radical prostatectomy, and cystoprostatectomy specimens, it has been suggested that the finding of intraluminal crystalloids in benign glands on needle biopsy may indicate a concurrent carcinoma; therefore, repeat biopsy is recommended. We studied data from 56 consecutive needle biopsies from the Johns Hopkins Hospital and Dianon Systems in which the diagnosis of intraluminal crystalloids in benign glands was rendered and follow-up data were subsequently obtained. Cases in which crystalloids were present in glands suspicious for cancer, in glands of high-grade prostatic intraepithelial neoplasia, or in adenosis were excluded from the study. Follow-up data included repeat biopsy results and serum prostatic specific antigen levels. Of the 56 men, 31 (55%) had repeat biopsy (two underwent transurethral resection of the prostate [TURP]); the remaining men were either noncompliant or had medical conditions precluding subsequent biopsy. Of the 31 men who underwent repeat biopsies, 23 (74%) had benign diagnoses, one (3%) had high-grade prostatic intraepithelial neoplasia, and seven (23%) had adenocarcinoma. There was no difference in serum prostate-specific antigen values between those with and without cancer on repeat biopsy. In a control population of men with a benign first biopsy not showing crystalloids, the incidence of cancer on repeat biopsy was 16.2%, which was not statistically significantly different from the incidence found in our study group. We conclude that men with prostate biopsy results showing benign glands with crystalloids are at no significantly higher risk of having cancer on repeat biopsy than if crystalloids were not present.

Prostate-specific antigen as a screening test for prostate cancer. The United States experience.

Serum PSA-based early detection for prostate cancer has been studied fairly extensively for the past several years. It appears that we can state fairly categorically what the relative performances of total serum PSA, DRE, and TRUS are in detecting early-stage prostate cancer; that initial screening is effective in detecting histologically significant and pathologically organ-confined prostate cancer; that annual, serial, repetitive screening, at least over a 4- to 5-year horizon, does not overdetect prostate cancer, and that the results of early detection will improve as our ability to use certain PSA transformations such as PSA density, PSA slope, age-specific PSA adjustment, and knowledge of free versus total serum PSA is better characterized. These advances in our ability to diagnose early-stage prostate cancer likely will be coupled with an increased ability to predict the behavior, curability, and significance of individual tumors. It is hoped that information soon will be available to allow physicians to categorize an individual tumor as insignificant, significant and surgically curable, or significant and incurable by standard approaches. This ability, coupled with the demonstrated ability to detect prostate cancer, will make an even more compelling argument for widespread PSA-based screening. At present, annual DRE and total serum PSA measurements are recommended for men older than 50 and among younger men at high risk for prostate cancer. All suspicious DRE findings should be evaluated with prostatic biopsy. Among younger men, PSA levels over 2.5 ng/mL should be considered worrisome and further evaluated. For men older than 65, serum PSA levels above 4 ng/mL should be considered abnormal and warrant biopsy. Men with persistent serum PSA elevation and a negative biopsy should undergo repeat biopsy at least once, and perhaps more often if PSA slope exceeds 0.75 per year, if density is greater than 0.10, or if f-PSA is less than 20%.

Comparison of percent free prostate-specific antigen levels in men with benign prostatic hyperplasia treated with finasteride, terazosin, or watchful waiting.

OBJECTIVES: Finasteride is known to lower total serum prostate-specific antigen (PSA) levels by approximately 50%. Terazosin is thought to have little or no effect on serum PSA concentration. The objective of our study was to determine the effect of finasteride and terazosin on serum total and serum free PSA levels and the ratio of free to total PSA. METHODS: We identified 69 men with symptomatic benign prostatic hyperplasia (BPH) who had been receiving 5 mg/day (n = 33) of finasteride or 2 to 5 mg/day (n = 14) of terazosin or no therapy ("watchful waiting") (n = 22). The three groups were compared with respect to pretreatment total serum PSA levels and post-treatment total, free, and percent free serum PSA levels. RESULTS: Median (+/- semi-interquartile range [SIR]) pretreatment total serum PSA levels (ng/mL) were not significantly different in men taking finasteride (2.8 +/- 1.9), terazosin (2.2 +/- 2.5), or undergoing watchful waiting (5.5 +/- 1.4) (P = 0.12). The median (+/- SIR) post-treatment total serum PSA levels (ng/mL) were significantly lower in the finasteride group (1.1 +/- 1) when compared with the terazosin (2.5 +/- 1.5) or watchful waiting (4.3 +/- 2.8) groups (P = 0.016). Only the finasteride group had significantly lower post-treatment total serum PSA levels compared with pretreatment levels. The median (+/- SIR) post-treatment free PSA levels were significantly lower in the finasteride group (0.26 +/- 0.16) compared with the terazosin (0.54 +/- 0.5) and watchful waiting (0.85 +/- 0.5) groups (P = 0.0015). However, the median (+/- SIR) percent free PSA was not significantly different in the finasteride (23 +/- 6), terazosin (22 +/- 4), and watchful waiting (25 +/- 5) groups (P = 0.66). CONCLUSIONS: Finasteride appears to lower total and free PSA levels equally in men with BPH and does not appear to change the ratio of free to total serum PSA. Terazosin does not appear to alter total or free serum PSA levels in men with BPH. The percent free PSA could potentially be used to screen for prostate cancer in men taking finasteride. Prospective studies are needed to further evaluate this issue.

Prostate specific antigen density versus prostate specific antigen slope as predictors of prostate cancer in men with initially negative prostatic biopsies.

PURPOSE: We determined if prostate specific antigen (PSA) density and PSA slope alone or in combination could be used to predict which men with persistently elevated serum PSA and prior negative prostate biopsies will have prostate cancer on repeat evaluation. MATERIALS AND METHODS: In our PSA-1 data base we identified 327 men 50 years old or older with an initially negative prostate biopsy who had persistent PSA elevation, and compared those who did and did not have prostate cancer on subsequent serial prostatic biopsy. RESULTS: Of 70 men with a PSA density of 0.15 or more and PSA slope of 0.75 ng./ml. or more annually compared to 83 with a PSA density of less than 0.15 and PSA slope of less than 0.75 ng./ml. annually 32 (46%) and only 11 (13%), respectively, had prostate cancer on subsequent prostate biopsies (p < 0.0001). In a hierarchical logistic regression analysis PSA density and PSA slope were predictive of prostate cancer on subsequent biopsy (p = 0.001 and 0.03, respectively). PSA density of 0.15 or more alone or PSA slope of 0.75 ng./ml. or more annually alone as the indicator for repeat biopsy would have missed 35 and 40% of cancers, respectively. CONCLUSIONS: In men with persistently elevated serum PSA after an initially negative prostate biopsy, PSA density and PSA slope alone or in combination provide useful predictive information about the results of repeat prostate biopsies. However, these parameters are not sufficiently sensitive to identify all patients with detectable prostate cancer.

Repeat biopsy strategy in men with isolated prostatic intraepithelial neoplasia on prostate needle biopsy.

PURPOSE: Isolated high grade prostatic intraepithelial neoplasia on needle biopsy of the prostate is a strong predictor of malignancy on repeat biopsy. However, the optimal repeat biopsy technique for these patients has not been defined. MATERIALS AND METHODS: We reviewed the records of 66 men in whom isolated prostatic intraepithelial neoplasia was found on needle biopsy of the prostate. We evaluated the side and/or quadrant and grade of prostatic intraepithelial neoplasia on initial biopsy, and compared the findings to the location of cancer on repeat biopsy. RESULTS: Of 66 men 31 (47%) had cancer on repeat biopsy, with disease on the same side of the prostate as prostatic intraepithelial neoplasia in 20 (64%). The quadrant locations of prostatic intraepithelial neoplasia and cancer matched in 6 of 12 cases (50%). Low and high grade prostatic intraepithelial neoplasia predicted the side of cancer on repeat biopsy in 3 of 5 (60%) and 17 of 26 (65%) cases, respectively. CONCLUSIONS: Directing repeat biopsy solely to the side with prostatic intraepithelial neoplasia will miss cancer in approximately 35% of cases. The optimal repeat biopsy technique for patients with high grade prostatic intraepithelial neoplasia should include systematic biopsy of the prostate.

Clinical and pathological features of hereditary prostate cancer.

PURPOSE: We determined whether the clinical and pathological features of hereditary prostate cancer differ from those of sporadic prostate cancer. MATERIALS AND METHODS: We compared the clinical and pathological features of radical prostatectomy specimens from 50 men with and 50 without a family history of prostate cancer who were matched for age and date of surgery. RESULTS: Median serum prostate specific antigen concentration was not significantly different in the 2 groups. Mean Gleason score plus or minus standard deviation in the 50 men with sporadic prostate cancer was 6.2 +/- 1 compared to 5.6 +/- 0.9 in those with hereditary disease (p = 0.008). Of the 50 hereditary and 50 sporadic prostate cancers 35 (70%) and 33 (66%), respectively, were pathologically organ confined (p = 0.69). Median percentage of carcinoma within the gland (determined morphometrically) in men with hereditary disease was 11.4 +/- 8.3 compared to 10.9 +/- 8.9 for those with sporadic cancer (p = 0.63). CONCLUSIONS: In our study population hereditary prostate cancers have significantly lower Gleason scores compared to sporadic carcinomas. Otherwise, there appear to be no substantial clinical or pathological differences.

Prospective characterization of pathological features of prostatic carcinomas detected via serum prostate specific antigen based screening.

PURPOSE: Many small (less than 0.5 cc), well differentiated, organ-confined prostate carcinomas remain clinically undetected during the life of the patient and are identified only at postmortem examination. Thus, these cancers are often called latent or autopsy cancers. There is concern that serum prostate specific antigen (PSA) based screening may preferentially detect these cancers. There are limited prospective data concerning the pathological features of carcinomas of the prostate detected in a screening program. We determined if prostatic carcinomas detected via PSA based screening resembled autopsy cancers. MATERIALS AND METHODS: We assessed the pathological features of carcinomas in 100 consecutive, completely embedded radical prostatectomy specimens from men whose cancer was detected in a PSA based screening program. The tumors were evaluated for pathological stage, surgical margin status, Gleason histological grade and intraglandular tumor extent (morphometrically quantified as percentage carcinoma and tumor volume). RESULTS: Of 100 carcinomas 68 (68%) were larger than 0.5 cc in volume (mean 1.7, range 0.1 to 10.7). Mean amount of carcinoma in the surgical specimen was 10.3% (range 0.1 to 41.6). Of the 100 carcinomas 94 had a Gleason score of 5 to 8 (mean 5.7) and only 6 (6%) were well differentiated (Gleason score of 4 or less). Locally advanced disease was noted in 41 cases (41%) as judged by the presence of extracapsular carcinoma and/or cancerous surgical margins. CONCLUSIONS: We concluded that the pathological features of most prostatic carcinomas detected via PSA based screening do not resemble those of autopsy cancers, and that most prostatic cancers detected in screening programs are likely to be clinically important.

Familial aspects of prostate cancer: a case control study.

PURPOSE: We evaluated the importance of positive family history, age at diagnosis and history of vasectomy in predicting the risk for prostate cancer in the brothers of prostate cancer patients. MATERIALS AND METHODS: A total of 1,084 men with newly diagnosed prostate cancer responded by interview to a family history survey, which included detailed information on the diagnosis of any cancer in the parents of the proband, diagnosis of prostate cancer in male relatives and age at onset of prostate cancer in the proband. A history of vasectomy was also obtained from the proband. The control cases consisted of 935 spouses of the probands who were administered the same questionnaire in an identical fashion. RESULTS: Prostate cancer was not significantly associated with other types of cancer in proband parents. The presence of prostate cancer in the father, grandfather or uncle of the proband significantly increased the risk of prostate cancer in proband brothers. Early age at onset in the proband was also associated with an increased risk to the proband brothers. CONCLUSIONS: Men with a family history of prostate cancer are at a significantly increased risk for prostate cancer, especially if the affected relative had early onset of cancer. Prostate cancer does not seem to be associated with a higher incidence of other cancers in family members.

Prostatic transition zone biopsies in men with previous negative biopsies and persistently elevated serum prostate specific antigen values.

PURPOSE: In men with persistently elevated serum prostate specific antigen (PSA) concentrations and prostatic biopsies that show no cancer an important question is whether the PSA elevation is caused by undetected cancer in the transition zone of the prostate gland. MATERIALS AND METHODS: To evaluate this issue further we examined 166 men age 50 years of older who participated in a PSA based screening trial for prostate cancer. All men had an initially elevated serum PSA concentration of 4.1 ng./ml. or greater. They had undergone 1 or 2 sets of negative peripheral zone biopsies of the prostate but elevated serum PSA concentrations persisted. They underwent repeat biopsy of the peripheral zone as well as 2 core biopsies from the right and 2 from the left transition zone region of the prostate. RESULTS: Peripheral and transition zone biopsies revealed cancer in 3 of 19 cases (16%). Cancer was present in the peripheral zone only biopsy in 14 of 19 cases (74%). Two of 19 cancers (10%) were detected only in the transition zone. Overall 17 of the 19 cancers (89%) were detected by peripheral zone biopsy. CONCLUSIONS: Transition zone biopsy detects few additional prostate cancers in men with persistent serum PSA elevations and previous negative biopsies.

Morphometric analysis and clinical followup of isolated prostatic intraepithelial neoplasia in needle biopsy of the prostate.

PURPOSE: We evaluate the significance of grade and extent of isolated prostatic intraepithelial neoplasia in prostate needle biopsies as a predictor of cancer on repeat biopsy. MATERIALS AND METHODS: We reviewed our experience with 58 men 50 years or older who had isolated prostatic intraepithelial neoplasia on initial prostate needle biopsy during a prostate specific antigen (PSA) based screening trial for prostate cancer. All 58 men underwent repeat biopsy to follow the initial findings of prostatic intraepithelial neoplasia. We assessed the relationship of patient age, digital rectal examination, serum PSA concentration, PSA density, prostatic intraepithelial neoplasia grade, number of foci of neoplasia and linear extent of prostatic intraepithelial neoplasia in the initial biopsy specimen to the finding of cancer on the repeat biopsy. We also compared the cancer detection rate in the 58 men with and 427 without prostatic intraepithelial neoplasia in the same screening trial. RESULTS: Of 21 men with low grade and 37 with high grade prostatic intraepithelial neoplasia 4 (19%) and 19 (51%), respectively, had cancer on repeat biopsy (p < 0.02), compared to 82 of 427 (19%) without cancer or prostatic intraepithelial neoplasia on the initial biopsy. High grade prostatic intraepithelial neoplasia was a significant predictor of malignancy on repeat biopsy (p < 0.05). The number of foci of neoplasia and the linear extent of prostatic intraepithelial neoplasia on initial biopsy were not predictive of cancer on repeat biopsy. CONCLUSIONS: Our results demonstrate that the presence of high grade prostatic intraepithelial neoplasia is a strong predictor of prostate cancer in men with elevated serum PSA concentrations and they should be followed with repeat biopsy.

Cryosurgical ablation of the prostate.

A new surgical procedure, cryosurgical ablation of the prostate, offers patients with organ-confined prostate cancer another treatment option. The advantages of this cryosurgical technique are complete ablation of prostatic cancers without radical prostatectomy procedures, less blood loss, decreased hospital stays, reduced health care costs, and minimal associated morbidity. Some possible complications of cryosurgical ablation of the prostate procedures include incontinence, impotence, rectal freezing from inadequate monitoring of the freezing process, urethrocutaneous and urethrorectal fistula formations, and urethral tissue sloughing. The intraoperative nurse's prime responsibility is to monitor the subfreezing temperatures of the cryoprobes. Postoperatively, patients have only a few perineal incisions covered with sterile dressings and a suprapubic catheter. Most patients have minimal discomfort that is managed easily with opiate analgesics.

Medical therapy for benign prostatic hyperplasia.

Benign prostatic hyperplasia (BPH) is a common clinical entity in elderly men. We review the epidemiology of BPH and the mechanisms by which it causes bladder outlet obstruction. The currently available medical therapies are examined with respect to mechanism of action, effectiveness, side effects, and cost. They are briefly compared with the more traditional treatment options of watchful waiting and transurethral prostatectomy. A logical approach to the treatment of symptomatic BPH is discussed.

Development of a mouse model for nonbacterial prostatitis.

Nonbacterial prostatitis is a common clinical entity which is often difficult to diagnose and treat. Little is known with regard to the etiology and pathogenesis of this disease process. To develop an animal model and characterize the immune parameters of nonbacterial prostatitis, we harvested the prostates from SJL, AJ, Balb/c, C57bl/6 and C57bl/6 lpr mice. These prostates were homogenized and injected into syngeneic mice. Controls were injected with Freund's complete adjuvant only. Mice from each group were sacrificed 30 days after injection, and the prostates were harvested. Prostatic tissue was examined histologically for degree of inflammation. None of the Balb/c mice exhibited prostatic inflammation. The SJL and AJ mice exhibited varying degrees of prostatic inflammation. All of the C57bl/6 mice were found to have lymphocytic infiltration of the stroma and periglandular region. The C57bl/6 lpr mice did not appear to be more susceptible than the parental strain. Adoptive transfer studies demonstrated the prostatic inflammation to be at least in part immune mediated. We conclude that injection of syngenic prostate antigen induces prostatic inflammation similar to clinical nonbacterial prostatitis. Nonbacterial prostatitis may be an autoimmune process.