The prognostic significance of DNA ploidy in clinically localized prostate cancer treated with radiation therapy

In Treating Localized Prostate Cancer the Efficacy of Cryoablation is Independent of DNA Ploidy Type

While the prognostic value of DNA ploidy has been well established for radical prostatectomy, external beam radiation, brachytherapy and androgen deprivation therapy its role as a survival outcome predictor for prostate cancer patients treated with cryoablation has not yet been examined. Anecdotal evidence suggesting that cryoablation may be independent of DNA ploidy type led to the implementation of the current study. Retrospective analysis of data including flow digital cytometry was performed on 447 archival specimens taken from patients who had undergone cryosurgical ablation of primary prostate cancer. Five-year biochemical disease free survivals (bDFS) (defined as PSA thresholds of 0.5 and 1.0 ng/ml) were determined with Kaplan-Meier analysis. Patients were grouped according to DNA ploidy types then stratified by Gleason grade, risk group, pre-surgical PSA level, and disease stage.

Mean and median age of the cohort was 65 and 64.6 years. Mean follow-up was 65.7 months. The DNA ploidy status of the population was found to be 59% diploid, 13% tetraploid, and 28% aneuploid. Using PSA < 1.0 ng/ml criterion, the bDFS rates for diploid, tetraploid, and aneuploid were 78%, 75%, and 79% respectively. The bDFS rates using a PSA < 0.5 ng/ml criterion were 67%, 59%, and 69% for diploid, tetraploid, and aneuploid groups. No significant outcome differences were found in stratified analysis. This investigation demonstrates that the efficacy of cryoablation is independent of DNA ploidy type.

Tissue biomarkers for prostate cancer radiation therapy

Prostate cancer is the most common cancer and second leading cause of cancer deaths among men in the United States. Most men have localized disease diagnosed following an elevated serum prostate specific antigen test for cancer screening purposes. Standard treatment options consist of surgery or definitive radiation therapy directed by clinical factors that are organized into risk stratification groups. Current clinical risk stratification systems are still insufficient to differentiate lethal from indolent disease. Similarly, a subset of men in poor risk groups need to be identified for more aggressive treatment and enrollment into clinical trials. Furthermore, these clinical tools are very limited in revealing information about the biologic pathways driving these different disease phenotypes and do not offer insights for novel treatments which are needed in men with poor-risk disease. We believe molecular biomarkers may serve to bridge these inadequacies of traditional clinical factors opening the door for personalized treatment approaches that would allow tailoring of treatment options to maximize therapeutic outcome. We review the current state of prognostic and predictive tissue-based molecular biomarkers which can be used to direct localized prostate cancer treatment decisions, specifically those implicated with definitive and salvage radiation therapy.

Identification of patients with low-risk for aneuploidy: comparative discriminatory models using linear and machine-learning classifiers in prostate cancer

BACKGROUND

Prostate needle biopsy (PNB) ploidy status has proven utility to predict adverse outcomes after prostatectomy. We sought to develop models to predict ploidy status using clinicopathologic variables.

METHODS

We identified a cohort of 169 patients with a diagnosis of prostatic adenocarcinoma on PNB, and estimated ploidy status (determined using Feulgen stained biopsy tissue) using four predictors, including age, prebiopsy PSA, highest Gleason score (GS), and the percentage of involvement by carcinoma at the biopsy site with the highest GS (PCARBX). Logistic regression (LR), Neural Network (NN), and CART classifiers were constructed.

RESULTS

Univariate analyses revealed all four predictors to be significantly associated with ploidy status. On multivariable analyses, LR identified a 2-parameter model, including GS and PCARBX that had a significant ability to predict ploidy status with a 74% and 75% correct classification rate (CCR), respectively. Using the same variables, CART and NN yielded similar CCRs of 70.4%. Within GS = 6 cohort, the CART model classified over 90% of biopsies as diploid when patients had a PCARBX < 55% and a log(PSA) < 1.7.

CONCLUSIONS

Our study demonstrates that models using GS and PCARBX are able to predict PNB ploidy status with acceptable accuracy. While machine learning classifier-derived models yield similar accuracy as LR-derived models, the latter methodology has the distinct advantage of being applicable in future datasets to estimate case-specific predictions. This information may be useful in identifying potentially aneuploid patients, who can then be targeted for more aggressive therapy.

The 20-Yr Outcome in Patients with Well- or Moderately Differentiated Clinically Localized Prostate Cancer Diagnosed in the Pre-PSA Era: The Prognostic Value of Tumour Ploidy and Comorbidity

OBJECTIVE

This observational cohort study describes the long-term outcome of patients with clinically localized prostate cancer managed with watchful waiting, the prognostic value of tumour ploidy, and the impact of comorbidity.

METHODS

A total of 119 patients with clinically localized (T1-2) prostate cancer consecutively diagnosed from 1978 to 1982 were prospectively managed by watchful waiting, with treatment given if progression occurred.

RESULTS

Median age was 68 yr. Median observation time was 24 yr+/-6.25 (SD). Of the 112 patients who died, 42 died of prostate cancer. Disease-specific survival rates were 85% (95% CI: 77-93%), 58% (46-70%), and 32% (19-46%) at 10, 15, and 20 yr, respectively. Treatment-free survival rate was 43% (95% CI: 33-54%) at 10 yr. Patients aged 70 yr and over had a statistically significant increased risk of dying from any cause. There was a statistically significant increased risk of dying from prostate cancer for patients with nondiploid tumours.

CONCLUSION

In the present series from the pre-PSA era, watchful waiting yielded a relatively high long-term disease-specific survival rate in patients with well- or moderately differentiated clinically localized prostate cancer, and almost half were not treated 10 yr after diagnosis. Watchful waiting may be an option at least for such patients with a 10- to 15-yr life expectancy. Age of 70 yr or more predicted an increased overall mortality. High comorbidity increased the risk (although not statistically significant) for death from any cause and for death from prostate cancer. Patients with nondiploid tumours were at an increased risk to die from prostate cancer.

Prostate cancer DNA ploidy and response to salvage hormone therapy after radiotherapy with or without short-term total androgen blockade: an analysis of RTOG 8610

PURPOSE

DNA ploidy has consistently been found to be a correlate of prostate cancer patient outcome. However, a minority of studies have used pretreatment diagnostic material and have involved radiotherapy (RT)-treated patients. In this retrospective study, the predictive value of DNA ploidy was evaluated in patients entered into Radiation Therapy Oncology Group protocol 8610. The protocol treatment randomization was RT alone versus RT plus short-course (approximately 4 months) neoadjuvant and concurrent total androgen blockade (RT+TAB).

PATIENTS AND METHODS

The study population consisted of 149 patients, of whom 74 received RT alone and 75 received RT+TAB. DNA content was determined by image analysis of Feulgen stained tissue sections; 94 patients were diploid and 55 patients were nondiploid. Kaplan-Meier univariate survival, the cumulative incidence method, and Cox proportional hazards multivariate analyses were used to evaluate the relationship of DNA ploidy to distant metastasis and overall survival.

RESULTS

DNA nondiploidy was not associated with any of the other prognostic factors in univariate analyses. In Kaplan-Meier analyses, 5-year overall survival was 70% for those with diploid tumors and 42% for nondiploid tumors. Cox proportional hazards regression revealed that nondiploidy was independently associated with reduced overall survival. No correlation was observed between DNA ploidy and distant metastasis. The diminished survival in the absence of an increase in distant metastasis was related to a reduction in the effect of salvage androgen ablation; patients treated initially with RT+TAB and who had nondiploid tumors had reduced survival after salvage androgen ablation.

CONCLUSIONS

Nondiploidy was associated with shorter survival, which seemed to be related to reduced response to salvage hormone therapy for those previously exposed to short-term TAB.

Predicting prostate carcinoma volume and stage at radical prostatectomy by assessing needle biopsy specimens for percent surface area and cores positive for carcinoma, perineural invasion, Gleason score, DNA ploidy and proliferation, and preoperative serum prostate specific antigen: a report of 454 cases

BACKGROUND

DNA ploidy analysis of prostate carcinoma is a generally accepted prognostic marker, particularly when tumors are extraprostatic at the time of surgery. In the past decade, the DNA content of prostate carcinoma frequently has been assessed in needle biopsy specimens based on the assumption that ploidy, in conjunction with serum prostate specific antigen (PSA) and Gleason score, provides valuable pretreatment information.

METHODS

Between 1995 and 1998, the authors identified a consecutive series of 454 prostate carcinomas, verified by needle biopsies and followed by radical retropubic prostatectomies (RRP). Based on the needle biopsies, DNA ploidy and MIB-I immunostaining were measured by digital image analysis (DIA). The authors also quantified the percent of nuclei in four categories from the DNA histograms. The DIA data were combined with the age of the patient at diagnosis, the serum PSA, Gleason score, percent cores and percent surface area positive for carcinoma, and status of perineural invasion in multivariate models using tumor volume and risk of extraprostatic extension (EPE) at RRP as the outcome variables.

RESULTS

Joint predictors of tumor volume at RRP were the percent cores positive for carcinoma (P < 0.0001), serum PSA (P < 0.0001), the percent surface area positive for carcinoma (P < 0.0001), and the percent nuclei classified by DNA quantification to be in the "S-phase" category (P = 0.03). Joint predictors of risk of EPE were the percent cores positive for carcinoma (P = 0.0004), a Gleason score of 7 (P < 0.0001), a Gleason score of 8 or 9 (P < 0.0001), serum PSA (P = 0.006) and perineural invasion (P = 0.02).

CONCLUSIONS

After adjusting for traditional prognostic markers, DNA ploidy interpretation and MIB-I quantitation of prostate carcinoma did not appear to jointly predict either outcome variable in the multivariate models. However, a quantitative measure related to both ploidy and proliferation, the percent of nuclei in the putative "S-phase" category from the DIA histograms, was found to jointly predict for tumor volume.

Relationship of Ki-67 labeling index to DNA-ploidy, S-phase fraction, and outcome in prostate cancer treated with radiotherapy

BACKGROUND

Our purpose was to evaluate the relationship of Ki-67 labeling index (Ki67-LI) to deoxyribonucleic acid (DNA) ploidy, S phase fraction (SPF), other clinical prognostic factors, and clinical outcome for patients with prostate cancer treated by external beam radiotherapy.

METHODS

Tissue was retrieved from 42 patients who underwent transurethral resection of the prostate before treatment with external beam radiotherapy between 1987-1993. DNA histogram profiles were classified as diploid (diploid + near-diploid) and nondiploid (tetraploid + aneuploid). Immunohistochemical staining of Ki-67 by the MIB-1 monoclonal antibody was used to calculate Ki67-LI. Median patient follow-up was 62 months. Treatment failure was defined as two consecutive rises in serum prostate-specific antigen (PSA) or clinical evidence of disease recurrence.

RESULTS

The mean and median Ki67-LIs were 3.1 and 2.4, respectively (range, 0-12.4). Mean Ki67-LI values were significantly associated with higher stage, Gleason score, and pretreatment PSA. Nondiploid tumors had significantly higher Ki67-LIs, as did patients who failed radiotherapy over the follow-up period. SPF was not significantly correlated with Ki67-LI. As a categorical variable, the most significant relationships were seen when Ki67-LI was subdivided into thirds around the median (Ki67-LI </=1.5%, Ki67-LI >1.5-3.5%, and Ki67-LI >3.5%). This trichotomous variable correlated significantly with pretreatment PSA (P = 0.0008), tumor stage (P = 0.016), Gleason score (P = 0.024), and treatment failure (P = 0.0015), but not with DNA-ploidy (P = 0.15). In actuarial univariate analyses, Ki67-LI appeared to be a more significant predictor of patient outcome (P = 0.003) than DNA-ploidy (P = 0.035).

CONCLUSIONS

The Ki67-LI correlated with known prognostic factors such as pretreatment PSA, tumor stage, and Gleason score, and was also weakly related to DNA-ploidy. In comparison to DNA-ploidy, Ki67 LI seems to be a better correlate of treatment outcome.

Familial prostate cancer: outcome following radiation therapy with or without adjuvant androgen ablation

PURPOSE

To compare the outcome of familial versus sporadic prostate carcinoma after definitive external radiation.

METHODS AND MATERIALS

Between 1987 and 1996, 1214 men with clinically localized prostate cancer (T1-T4, N0/NX, M0) received definitive radiation therapy in our department. By retrospective review of charts and questioning of patients, a record on the presence or absence of prostate cancer in a first degree relative was obtained in 1164 men. Univariate and multivariate analysis was performed on these cases with relapse or rising prostate-specific antigen (PSA), local recurrence, metastasis, and survival as endpoints.

RESULTS

Familiar prostate cancer was present in 148 of 1164 men (13%). Men with familial disease were slightly but significantly younger (mean 66 years) at diagnosis than those with sporadic disease (mean 68 years) (p = 0.02). Apart from this there were no significant differences between the two groups in T-stage, Gleason score, pretreatment PSA levels, DNA ploidy, or serum testosterone levels. There were no significant differences in treatment parameters including radiation dose and the use of adjuvant androgen ablation. With a median follow-up of 42 months, there was no difference in freedom from relapse or rising PSA at 6 years between those with a family history (54%) and those without a family history (58%) (p = 0.171). Likewise there was no difference between the two groups when local recurrence or metastasis was the endpoint. Multiple subgroup analyses (younger and older; T1/T2 and T3; low Gleason and high Gleason; no androgen ablation and androgen ablation; race) failed to reveal any differences in outcome in any category between familial and sporadic disease. Among patients with a rising post-treatment PSA profile, PSA doubling times were similar in those with sporadic and familial disease.

CONCLUSIONS

This study provides no evidence for any substantial difference between familial and sporadic prostate cancer either in clinicopathological features, in response to treatment, or in ultimate outcome.

Prostate cancer in African-American men: outcome following radiation therapy with or without adjuvant androgen ablation

PURPOSE

To compare the outcome of irradiated clinically localized prostate cancer in African-American and white patients.

METHODS AND MATERIALS

This was a retrospective review of 1,201 men, 116 African-American and 1,085 white, with T1-T3, N0/NX, M0 prostate cancer receiving external radiation between 1987 and 1996. Pretreatment characteristics, treatment parameters, and outcome (relapse or rising prostate-specific antigen [PSA] levels, local recurrence, metastatic relapse, and survival) were compared between the groups using univariate and multivariate statistical methods.

RESULTS

There were no significant differences between African-American and white patients in T-stage, Gleason score, prostatic acid phosphatase (PAP) level, and testosterone level. African-Americans had a significantly lower incidence of abnormal digital rectal findings and a proportionally higher incidence of obstructive urinary symptoms at presentation and tended to be somewhat younger. A major difference between the two groups was in the significantly higher PSA levels among African-Americans (median, 14 ng/ml) than among white patients (median, 9.5 ng/ml). This translated into a higher incidence of unfavorable disease according to our criteria (39% vs. 25%) among African-Americans and, thus, to the more frequent use of adjuvant androgen ablation and to somewhat higher radiation doses in these patients. With a median follow-up of 42 months the overall 6-year freedom from relapse for African-Americans was 63% compared to 61% for whites (p = 0.634). We found no significant differences in biochemical relapse rates between any subgroups of African-Americans and whites. Specifically, even patients who did not have androgen ablation, when stratified by PSA levels, had similar outcomes regardless of race. Likewise, local recurrence and metastasis rates were not significantly different between the two groups.

CONCLUSIONS

Although African-American patients tend to have higher pretreatment PSA levels than white patients, the outcome for the disease is similar in the two groups when stratified by known pretreatment prognostic factors. Our data provide no evidence for the hypothesis that prostate cancer in African-Americans is intrinsically more virulent than in whites.

The significance of DNA-ploidy and S-phase fraction in node-positive (stage D1) prostate cancer treated with androgen ablation

BACKGROUND

The prognostic significance of primary tumor DNA-ploidy and S-phase fraction (SPF) was evaluated in patients treated with androgen ablation for regionally localized node-positive prostate cancer.

METHODS

All patients were diagnosed with lymph node involvement by pelvic lymphadenectomy between 1984 and 1992 and were treated only with androgen ablation. Median follow-up was 45 months. Adequate material for DNA/nuclear protein flow cytometric analysis was available in 33 patients.

RESULTS

The tumors were classified as diploid in 11, near-diploid in 4, tetraploid in 10, and aneuploid in 8 cases. Grouping the patients by nonaneuploidy (diploid and near-diploid and tetraploid) and aneuploidy revealed actuarial 4-year disease progression rates of 14 and 48% (log-rank, P = 0.04), and overall survival rates of 100 and 61% (P = 0.008); however, biochemical progression (rising prostate-specific antigen profile) rates were similar at around 70%. In contrast, SPF was not significantly related to any of the endpoints tested. Several other potential prognostic factors were examined and none correlated significantly with disease progression or survival.

CONCLUSIONS

The biochemical progression rates for patients with nonaneuploid and aneuploid tumors were comparable and high, while the disease progression rates were higher and survival rates lower for those with aneuploid tumors. These data indicate that the lead time from biochemical to disease progression and death was shorter with aneuploidy. That these relationships were observed in such a small patient population attest to the strength of DNA-ploidy as a prognostic factor in this cohort.

A multiple prognostic index predictive of disease outcome after irradiation for clinically localized prostate carcinoma

BACKGROUND

This investigation was conducted to identify independent pretherapy disease-related factors associated with disease outcome in patients with clinically localized carcinoma of the prostate (CaP) and to develop models that incorporated relevant covariates for estimating the risk of disease relapse after irradiation (RT).

METHODS

The outcome of 500 patients treated only with RT between March 1987 and June 1993 for clinical Stages T1-4N0,XM0 CaP was evaluated. The risk of disease relapse as a function of individual prognostic variables, and combinations thereof, was determined using logistic regression.

RESULTS

With a median follow-up of 43 months (range, 4-103 months), 69 patients (14%) had clinical evidence of local recurrence (27 patients), regional lymph node relapse (4 patients), or metastatic relapse (38 patients) within 5 years of RT. Forty additional patients (8%) had biochemical relapse based solely on the post-RT serum prostate specific antigen (PSA) profile. Clinical tumor stage (P = 0.0006), Gleason score (P = 0.001) of the diagnostic biopsy specimen, and pretherapy PSA (P < 0.0001) were associated with disease relapse. The risk of any relapse within 5 years of RT was determined and graphically displayed as risk estimate plots for combinations of these pretherapy prognostic variables.

CONCLUSIONS

The combination of pretherapy clinical tumor (T) stage, Gleason score, and PSA level can be used to obtain improved estimates of the risk for disease relapse in patients treated solely with RT for clinically localized CaP. Risk estimate plots of this type may facilitate exchange of therapeutic outcome information, be instrumental in pretherapy decision-making for the new patient with this condition, and aid in the selection of patients for future studies.

Prostate-specific antigen and radiation therapy for clinically localized prostate cancer

PURPOSE

This study was undertaken to: (a) define the prognostic significance of pretreatment serum prostate-specific antigen (PSA) levels in localized prostate cancer treated with radiation; (b) define the prognostic usefulness of postradiation PSA levels; (c) evaluate the outcome of radiation using PSA as an endpoint.

METHODS AND MATERIALS

Disease outcome in 707 patients with Stages T1 (205 men), T2 (256 men), T3 (239 men), and T4 (7 men), receiving definitive external radiation as sole therapy, was evaluated using univariate and multivariate techniques.

RESULTS

At a mean follow-up of 31 months, 157 patients (22%) developed relapse or a rising PSA. Multivariate analysis revealed pretreatment PSA level to be the most significant prognostic factor, with lesser though significant contributions due to Gleason grade (2-6 vs. 7-10) and transurethral resection in T3/T4 disease. The following four prognostic groupings were defined: group I, PSA < or = 4 ng/ml, any grade; group II, 4 < PSA < or = 20, grades 2-6; group III, 4 < PSA < or = 20, grades 7-10; group IV, PSA > 20, any grade. Five-year actuarial relapse rates in these groups were: I, 12%; II, 34%; III, 40%; and IV, 81%. Posttreatment nadir PSA was an independent determinant of outcome and only patients with nadir values < 1 ng/ml fared well (5-year relapse rate 20%). Using rising PSA as an endpoint the 461 patients with T1/T2 disease had an actuarial freedom from disease rate of 70% at 5 years, which appeared to plateau, suggesting that many were cured. No plateau was evident for T3/T4 disease.

CONCLUSION

Pretreatment serum PSA is the single most important predictor of disease outcome after radiation for local prostate cancer. Tumor grade has a lesser though significant prognostic role. Postirradiation nadir PSA value during the first year is a sensitive indicator of response to treatment. Only nadir values < 1 ng/ml are associated with a favorable outlook. A significant fraction of men with T1/T2 disease may be cured with radiation. There was no evidence for a cured fraction among patients with T3/T4 disease.

Significance of tumor angiogenesis in clinically localized prostate carcinoma treated with external beam radiotherapy

OBJECTIVES

To determine the prognostic significance of microvessel density (a measure of tumor angiogenesis) in comparison with other prognostic factors for patients with clinically localized prostatic carcinoma treated with external beam radiotherapy.

METHODS

Microvessel density was quantified within the initial invasive carcinoma from the diagnostic transurethral resection specimen of 25 patients with a mean follow-up of 44 months. Microvessels were identified by immunohistochemical staining of endothelial cells for factor VIII-related antigen in formalin-fixed, paraffin-embedded tissue. Microvessels were counted in a x200 field (0.754 mm2) in the area of maximal angiogenesis.

RESULTS

Microvessel density correlated with several pretreatment prognostic factors, including prostate-specific antigen (PSA) (p < 0.0001), tumor grade (p = 0.006), and ploidy (p = 0.016). The degree of tumor angiogenesis also correlated with outcome following external beam radiotherapy. The mean microvessel count in the nine tumors from patients who failed radiotherapy (ie, had rising PSA and/or clinical relapse) was 97.0 +/- 33.6 (+/- SD) per x200 field compared with 46.1 +/- 17.1 for the 16 patients with no evidence of failure (p < 0.0001). Increased microvessel density was also associated with a significantly worse actuarial outcome at 4 years using either biochemical relapse (rising PSA) or a composite endpoint of rising PSA or clinical relapse (p = 0.0003).

CONCLUSIONS

The intratumoral quantification of tumor angiogenesis may prove valuable as a prognostic indicator in patients with clinically localized prostate cancer treated with radiotherapy.

Relationship of tumor DNA-ploidy to serum prostate-specific antigen doubling time after radiotherapy for prostate cancer

OBJECTIVES

DNA-ploidy is a strong prognostic factor for prostate cancer patients treated with definitive external beam radiotherapy. Using DNA/nuclear protein flow cytometry, three prognostic groups based on DNA-ploidy were identified: from good to poor, these are diploid, near-diploid, and nondiploid tumors. Since recent evidence indicates that the rate at which prostate-specific antigen (PSA) increases in the presence of biochemical failure is predictive of the time to clinical relapse, we examined the relationship between DNA-ploidy and PSA doubling time (PSA-DT).

METHODS

Formalin-fixed paraffin-embedded tissues from 76 patients treated at M.D. Anderson Cancer Center with definitive radiotherapy alone were analyzed for ploidy using DNA/nuclear protein flow cytometry. Of these, 24 of the 27 patients with a rising PSA profile had three or more post-treatment PSA values from which the PSA-DTs were calculated. PSA-DTs were estimated using nonlinear regression techniques.

RESULTS

The average PSA-DT for the 24 patients in this cohort was 11.3 +/- 10.5 months (+/- SD) with a median of 8.4 months. Diploidy (n = 3) was associated with a PSA-DT of 27.0 +/- 22.8 months, near-diploidy (n = 7) with a PSA-DT of 12.2 +/- 5.7 months, and non-diploidy (n = 14) with a PSA-DT of 7.5 +/- 5.7 months (p = 0.004, Spearman rank test). Stage, grade, and pretreatment PSA, as well as the endpoints of local control, freedom from metastases, and freedom from any relapse, did not correlate significantly with PSA-DT values. However, when patients were subdivided by PSA-DT into those with values 10 months or less (n = 14) and those more than 10 months (n = 10), there was a correlation with 3-year actuarial freedom from relapse: 28% and 74%, respectively (p < 0.01, log-rank). This subdivision of PSA-DT also correlated with DNA-ploidy (p = 0.03, chi-square) and stage (p = 0.04).

CONCLUSIONS

The results show that there is a significant correlation of DNA-ploidy with PSA-DT. Diploidy was associated with the longest PSA-DTs, near-diploidy with intermediate PSA-DTs, and nondiploidy with short PSA-DTs. Patients with short PSA-DTs also had significantly higher actuarial rates of disease relapse at 3 years. These data confirm that PSA-DT is a strong predictor of tumor behavior and that patients who have nondiploid tumors probably require more aggressive, combined modality, treatment.

Prostate cancer

Prostate cancer is the most common noncutaneous malignancy diagnosed in American men, and in 1994 it will pass lung cancer as the most common cancer diagnosed in the United States, with an estimated 200,000 new cases. The molecular biology of prostate carcinogenesis is rapidly advancing, and it is clear that, to a degree, prostate cancer is a heritable disease. The use of serum prostate-specific antigen (PSA) as a screening tool has been widely accepted by the medical community, although the evidence to support the efficacy of screening is not yet available. The curative approaches to organ-confined, clinically localized prostate cancer include radiation therapy, radical prostatectomy, and close observation in selected patients. The absence of well-designed clinical trials contributes to the confusion surrounding which curative treatment is the best option in individual patients. The standard approach to patients with evidence of extracapsular spread without distant metastases has been external-beam radiotherapy, although the results with radiation therapy alone in these patients has left considerable room for improvement. Innovative combined-modality approaches are currently being investigated at a number of institutions for these poor-prognosis patients. Three-dimensional conformal radiation therapy is currently being investigated at multiple institutions and offers some hope for improved results. The treatment of metastatic disease remains hormonal manipulation, although the exact nature of optimal androgen deprivation is currently a matter of considerable debate. In patients with hormone-refractory disease newer regimens using novel chemotherapy regimens offer some promise.