Carcinoma of the prostate: race as a prognostic indicator in definitive radiation therapy

Evaluation of Social Determinants of Health and Prostate Cancer Outcomes Among Black and White Patients: A Systematic Review and Meta-analysis

IMPORTANCE

As the field of medicine strives for equity in care, research showing the association of social determinants of health (SDOH) with poorer health care outcomes is needed to better inform quality improvement strategies.

OBJECTIVE

To evaluate the association of SDOH with prostate cancer-specific mortality (PCSM) and overall survival (OS) among Black and White patients with prostate cancer.

DATA SOURCES

A MEDLINE search was performed of prostate cancer comparative effectiveness research from January 1, 1960, to June 5, 2020.

STUDY SELECTION

Two authors independently selected studies conducted among patients within the United States and performed comparative outcome analysis between Black and White patients. Studies were required to report time-to-event outcomes. A total of 251 studies were identified for review.

DATA EXTRACTION AND SYNTHESIS

Three authors independently screened and extracted data. End point meta-analyses were performed using both fixed-effects and random-effects models. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed, and 2 authors independently reviewed all steps. All conflicts were resolved by consensus.

MAIN OUTCOMES AND MEASURES

The primary outcome was PCSM, and the secondary outcome was OS. With the US Department of Health and Human Services Healthy People 2030 initiative, an SDOH scoring system was incorporated to evaluate the association of SDOH with the predefined end points. The covariables included in the scoring system were age, comorbidities, insurance status, income status, extent of disease, geography, standardized treatment, and equitable and harmonized insurance benefits. The scoring system was discretized into 3 categories: high (≥10 points), intermediate (5-9 points), and low (<5 points).

RESULTS

The 47 studies identified comprised 1 019 908 patients (176 028 Black men and 843 880 White men; median age, 66.4 years [IQR, 64.8-69.0 years]). The median follow-up was 66.0 months (IQR, 41.5-91.4 months). Pooled estimates found no statistically significant difference in PCSM for Black patients compared with White patients (hazard ratio [HR], 1.08 [95% CI, 0.99-1.19]; P = .08); results were similar for OS (HR, 1.01 [95% CI, 0.95-1.07]; P = .68). There was a significant race-SDOH interaction for both PCSM (regression coefficient, -0.041 [95% CI, -0.059 to 0.023]; P < .001) and OS (meta-regression coefficient, -0.017 [95% CI, -0.033 to -0.002]; P = .03). In studies with minimal accounting for SDOH (<5-point score), Black patients had significantly higher PCSM compared with White patients (HR, 1.29; 95% CI, 1.17-1.41; P < .001). In studies with greater accounting for SDOH variables (≥10-point score), PCSM was significantly lower among Black patients compared with White patients (HR, 0.86; 95% CI, 0.77-0.96; P = .02).

CONCLUSIONS AND RELEVANCE

The findings of this meta-analysis suggest that there is a significant interaction between race and SDOH with respect to PCSM and OS among men with prostate cancer. Incorporating SDOH variables into data collection and analyses are vital to developing strategies for achieving equity.

Race-specific prostate cancer outcomes in a cohort of low and favorable-intermediate risk patients who underwent external beam radiation therapy from 1990 to 2017

BACKGROUND

Previous research exploring the role of race on prostate cancer (PCa) outcomes has demonstrated greater rates of disease progression and poorer overall survival for African American (AA) compared to Caucasian American (CA) men. The current study examines self-reported race as a predictor of long-term PCa outcomes in patients with low and favorable-intermediate risk disease treated with external beam radiation therapy (EBRT).

METHODS

This retrospective cohort study examined patients who were consented to enrollment in the Center for Prostate Disease Research Multicenter National Database between January 01, 1990 and December 31, 2017. Men self-reporting as AA or CA who underwent EBRT for newly diagnosed National Comprehensive Cancer Network-defined low or favorable-intermediate risk PCa were included. Dependent study outcomes included: biochemical recurrence-free survival, (ii) distant metastasis-free survival, and (iii) overall survival. Each outcome was modeled as a time-to-event endpoint using race-stratified Kaplan-Meier estimation curves and multivariable Cox proportional hazards analysis.

RESULTS

Of 840 men included in this study, 268 (32%) were AA and 572 (68%) were CA. The frequency of biochemical recurrence, distant metastasis, and deaths from any cause was 151 (18.7%), 29 (3.5%), and 333 (39.6%), respectively. AA men had a significantly younger median age at time of EBRT and slightly higher biopsy Gleason scores. Multivariable Cox proportional hazards analyses demonstrated no racial differences in any of the study endpoints.

CONCLUSIONS

These findings reveal no racial disparity in PCa outcomes for AA compared to CA men, in a long-standing, longitudinal cohort of patients with comparable access to cancer care.

Rethinking active surveillance for prostate cancer in African American men

Active surveillance (AS) is a treatment modality for prostate cancer that aims to simultaneously avoid overtreatment and allow for the timely intervention of localized disease. AS has become the de facto standard of care for most men with low-risk prostate cancer. However, few African American (AA) men were included in the prospective observational cohorts that resulted in a paradigm shift in treatment recommendations from active intervention toward AS. It has been established that AA men have an increased prostate cancer incidence, higher baseline prostate-specific antigen (PSA) values, more aggressive prostate cancer features, greater frequency of biochemical recurrence after treatment, and higher overall cancer-specific mortality compared to their Caucasian counterparts. As such, this has given many physicians pause before initiating AS for AA patients. In the following manuscript, we will review the available literature regarding AS, with a particular focus on AA men. The preponderance of evidence demonstrates that AS is as viable a management method for AA with low-risk prostate cancer as it is with other racial groups.

Do African American Men Have Lower Survival From Prostate Cancer Compared With White Men? A Meta-analysis

Prostate cancer is the second leading cause of cancer-related mortality in men. This meta-analysis was conducted to investigate the relationship between race and survival from prostate cancer. A systematic review of articles published from 1968 to 2007 assessing survival from prostate cancer was conducted. Analysis of unadjusted studies reported that African American men have an increased risk of all-cause mortality (hazard ratio [HR] = 1.47, 95% confidence interval [CI] = 1.31-1.65, p < .001). However, examination of adjusted studies identified no difference (HR = 1.07, 95% CI = 0.94-1.22, p = .308). No statistically significant difference was observed in prostate cancer—specific survival in both analyses using unadjusted (HR = 1.11, 95% CI = 0.94-1.31, p = .209) and adjusted studies (HR = 1.15, 95% CI = 0.95-1.41, p = .157). This meta-analysis concludes that there are no racial differences in the overall and prostate cancer—specific survival between African American and White men.

Race and socioeconomic status influence outcomes of unrelated donor hematopoietic cell transplantation

Success of hematopoietic cell transplantation (HCT) can vary by race, but the impact of socioeconomic status (SES) is not known. To evaluate the role of race and SES, we studied 6207 unrelated-donor myeloablative (MA) HCT recipients transplanted between 1995 and 2004 for acute or chronic leukemia or myelodysplastic syndrome (MDS). Patients were reported by transplant center to be White (n = 5253), African American (n = 368), Asian/Pacific-Islander (n = 141), or Hispanic (n = 445). Patient income was estimated from residential zip code at time of HCT. Cox regression analysis adjusting for other significant factors showed that African American (but not Asian or Hispanic) recipients had worse overall survival (OS) (relative-risk [RR] 1.47; 95% confidence interval [CI] 1.29-1.68, P < .001) compared to Whites. Treatment-related mortality (TRM) was higher in African Americans (RR 1.56; 95% CI 1.34-1.83, P < .001) and in Hispanics (RR 1.30; 95% CI 1.11-1.51, P = .001). Across all racial groups, patients with median incomes in the lowest quartile (<$34,700) had worse OS (RR 1.15; 95% CI 1.04-1.26, P = .005) and higher risks of TRM (RR 1.21; 1.07-1.36, P = .002). Inferior outcomes among African Americans are not fully explained by transplant-related factors or SES. Potential other mechanisms such as genetic polymorphisms that have an impact on drug metabolism or unmeasured comorbidities, socioeconomic factors, and health behaviors may be important. Low SES, regardless of race, has a negative impact on unrelated donor HCT outcomes.

Predictors of aggressive therapy for nonmetastatic prostate carcinoma in Massachusetts from 1998 to 2002

BACKGROUND

Most studies have found that black men are less likely to receive aggressive therapy for nonmetastatic prostate cancer, even after controlling for covariates. However, previous studies have not accounted for the clustering of outcomes by facility.

OBJECTIVE

We sought to compare the proportions of black and white men receiving aggressive therapy for newly diagnosed nonmetastatic prostate cancer between 1998 and 2002, accounting for the clustering of outcomes by facility.

METHODS

We used the Massachusetts Cancer Registry of all cancer diagnosed in residents of Massachusetts. We used logistic regression, clustering by the facility where the tumor was diagnosed, to predict the probability that a patient would receive any aggressive therapy, and the specific therapeutic choices of radical prostatectomy, external-beam radiation therapy, and brachytherapy. Predictors included race, age, poverty, insurance status, marital status, year of diagnosis, and tumor grade.

RESULTS

Black men were similarly likely to receive aggressive therapy compared with white men (odds ratio [OR] 0.79, 95% confidence interval [CI] 0.62-1.01). However, there was a racial difference in the receipt of particular types of therapy: black men were significantly more likely to receive radiation therapy (OR 1.39, 95% CI 1.16-1.68) and less likely to receive radical prostatectomy (OR 0.53, 95% CI 0.38-0.74).

CONCLUSIONS

Among men diagnosed with nonmetastatic prostate cancer in Massachusetts from 1998 to 2002, black men received aggressive therapy at rates approaching those of whites. However, they were more likely to receive radiation therapy and less likely to receive radical prostatectomy.

Outcome of Ethnic Minorities With Acute or Chronic Leukemia Treated With Hematopoietic Stem-Cell Transplantation in the United States

Purpose

We previously reported a higher risk of mortality among Hispanics after allogeneic hematopoietic stem-cell transplantation (HSCT). However, it is not known how specific post-transplantation events (acute or chronic graft-versus-host disease [GVHD], treatment-related mortality [TRM], and relapse) may explain mortality differences. The purpose of this study was to examine the relationship between ethnicity and post-transplantation events and determine their net effect on survival.

Patients and Methods

We identified 3,028 patients with acute myeloid leukemia, acute lymphoblastic leukemia, or chronic myeloid leukemia reported to the International Bone Marrow Transplant Registry between 1990 and 2000 who received an HLA-identical sibling HSCT after a myeloablative conditioning regimen in the United States. There were 2,418 white patients (80%) and 610 ethnic minority patients (20%), of whom 251 were black (8%), 122 were Asian (4%), and 237 were Hispanic (8%). Cox proportional hazards regression was used to compare outcomes between whites and ethnic minorities while adjusting for other significant clinical factors.

Results

No statistically significant differences in the risk of acute or chronic GVHD, TRM, or relapse were found between whites and any ethnic minority group. However, Hispanics had higher risks of treatment failure (death or relapse; relative risk [RR] = 1.30; 95% CI, 1.08 to 1.54; P = .004) and overall mortality (RR = 1.23; 95% CI, 1.03 to 1.47; P = .02).

Conclusion

The higher risks of treatment failure and mortality among Hispanics may be the net result of modest but not statistically significant increases in both relapse and TRM and cannot be accounted for by any single transplantation-related complication. Further studies should examine the role of social, economic, and cultural factors.

Racial differences in prostate cancer treatment outcomes: a systematic review

Although differences in prostate cancer incidence and mortality between black and white men are widely accepted, the existence of racial differences in treatment outcomes remains controversial. We conducted a systematic review of racial differences in prostate cancer treatment outcomes. Systematic review of literature from 1992-2002 was conducted. Database searches were performed using the terms: "prostate cancer" (keyword) or "prostate neoplasm" (subject heading) + "blacks" (subject heading) or "blacks" (keyword) + "African-Americans" (subject heading or "African-Americans" (keyword). Two hundred fifty-eight relevant articles were identified; 29 fit the inclusion criteria. All but 3 were retrospective. Seven (24%) studies were conducted at Veterans Affairs medical centers. Treatment included radical prostatectomy (15 studies), hormonal therapy (5 studies), and radiotherapy (12 studies). Three studies included more than 1 treatment. Twenty-three (79%) studies, observed no significant difference in treatment outcomes between races. The remainder found worse outcomes among black men, including worse 5-year survival (HR range, 2.35-96.74) and higher rates of PSA failure (OR range, 1.15-1.69). Most studies investigating racial differences in prostate cancer treatment outcomes over the past 10 years found no difference between races after controlling for tumor and patient characteristics. Efforts to narrow the gap between black and white prostate cancer mortality should focus on ensuring that all patients receive optimal treatment and that all patients become informed about the use of screening for early cancer detection. Research should focus on interventions to reduce advanced presentation of the disease and disease-related mortality among black men.

Explaining racial differences in prostate cancer in the United States: sociology or biology?

Black men in the United States have the highest incidence and mortality from prostate cancer in the world. Even after adjusting for stage at diagnosis, black men have higher mortality rates than white men. Multiple reasons have been postulated to explain these findings including access to care, attitudes about care, socioeconomic and education differences, differences in type and aggressiveness of treatment, dietary, and genetic differences. While each reason may contribute to the higher incidence or higher mortality, likely combinations of reasons will best explain all the findings. Racial differences in socioeconomic status have been well established and we review the significance of these findings in relationship to prostate cancer. Also, with recent advances in the understanding of genetic variation in the human genome, in general, and in the genes involved in pathways relevant to prostate cancer biology, in particular, a number of genes with alleles which differ in frequency between black and white men have been proposed as a genetic cause or contributor to the increased prostate cancer risk in black men. However, the clinical significance of these genetic differences is not fully known. Finally, we conclude with some thoughts as to how to integrate the findings from sociological as well as biological studies and touch upon methods to reduce the disparate burden of prostate cancer among blacks in the United States.

Children from ethnic minorities have benefited equally as other children from contemporary therapy for rhabdomyosarcoma: a report from the Intergroup Rhabdomyosarcoma Study Group

PURPOSE

To define the clinical characteristics of rhabdomyosarcoma (RMS) occurring in children from ethnic minorities and determine whether these children have benefited equally from advances in therapy.

PATIENTS AND METHODS

This was a retrospective cohort analysis of children treated on the Intergroup Rhabdomyosarcoma Study Group protocols between 1984 and 1997. The clinical features and outcomes of 336 African-American children and 286 children from other ethnic minorities were compared with those of white children (n = 1,721).

RESULTS

African-American, other ethnic group, and white children enjoyed similar 5-year failure-free survivals (FFS) of 61%, 61%, and 66%, respectively, P =.15. Compared with white children, nonwhite patients more often had (1) invasive, T2 tumors (P =.03); (2) stage 2 or 3 tumors (P =.003); (3) large tumors (more than 5 cm, P <.006); and/or (4) tumors with positive regional nodes (ie, N1, P =.002). Using Cox proportional hazards analysis, seven patient risk categories were defined with significant differences in outcome. This model was then used to search for other factors associated with FFS after adjusting for these risk categories. Only T stage and age remained associated with FFS (P =.001 and P <.001, respectively). After adjusting for T stage, risk category, and age, we explored the relationship of ethnic group to FFS and found that, compared with whites, the relative risk of failure was 1.14 for African-American patients and 1.2 for other ethnic minority patients, values that are not significantly different.

CONCLUSION

Patients from ethnic minority groups more often have larger, invasive tumors with positive lymph nodes. Nevertheless, they have benefited as equally as white children from the dramatic progress in therapy of RMS.

Effect of race on biochemical disease-free outcome in patients with prostate cancer treated with definitive radiation therapy in an equal-access health care system: radiation oncology report of the Department of Defense Center for Prostate Disease Research

PURPOSE

To report on the first collaboration of the Department of Defense Center for Prostate Disease Research concerned with the relationship between African American race and biochemical disease-free outcomes after definitive radiation therapy.

MATERIALS AND METHODS

Information from the medical records of 1,806 patients (1,349 white, 343 African American, 42 of "other" races, and 72 of "unknown" races) treated with definitive radiation therapy between 1973 and 2000 was reviewed. Patients receiving adjuvant hormonal therapy or postoperative adjuvant or salvage radiation therapy were excluded. Biochemical failure was calculated in over 96% of cases by using ASTRO criteria; patients with fewer than three follow-up visits were considered to have biochemical failure with a prostate-specific antigen (PSA) value more than 10-fold the previous value or with any value greater than 50.0 ng/mL. Median radiation therapy doses were similar. The median follow-up was 58.4 months. Kaplan-Meier tests, Cox proportional hazards regression analysis, and log-rank tests were used for data analysis.

RESULTS

There was no statistically significant difference in biochemical disease-free survival according to race when patients were stratified according to T stage. African American race conferred a negative prognosis for patients with lesions of Gleason biopsy score 7 (P =.004) but not for patients with lesions of Gleason score 2-4 (P =.14), 5-6 (P =.79), or 8-10 (P =.86). Similarly, African American race conferred a negative prognosis in patients with PSA values of 20.1-50.0 ng/mL (P =.01) at presentation but not in patients with PSA values less than or equal to 4.0 ng/mL (P =.84), 4.1-10.0 ng/mL (P =.71), 10.1-20.0 ng/mL (P =.75), or above 50.0 ng/mL (P =.15) at presentation. At multivariate analysis, race was not a statistically significant predictor of outcome.

CONCLUSION

In the equal-access health care system of the Department of Defense, African American race is not associated with a consistently negative prognosis in patients treated with definitive radiation therapy for prostate cancer. Race appears to confer a negative prognosis only in patients with advanced disease at presentation.

The impact of race on biochemical disease-free survival in early-stage prostate cancer patients treated with surgery or radiation therapy

PURPOSE

To assess the impact of race on biochemical freedom from recurrence in patients with early-stage prostate cancer treated either by radical prostatectomy or radiation therapy.

METHODS

Between July 1989 and December 1994, 693 patients with early-stage prostate cancer were treated with radiation (302 patients) or by radical prostatectomy (391 patients) at Barbara Ann Karmanos Cancer Institute/Wayne State University. Stage, Gleason score, race, pretreatment PSA, and follow-up PSA values were abstracted. There were 387 Caucasian males (CM) and 306 African-American males (AAM). None of the patients received hormone therapy. Radiation therapy was delivered using photon irradiation (249 patients, median dose 69 Gy) or mixed neutron/photon irradiation (53 patients, median dose 10 NGy + 38 PGy). Median follow-up was 36 months (range 2-70) for CM and 35 months (range 1-70) for AAM.

RESULTS

Thirty-seven percent of patients treated surgically were AAM, compared to 53% in the radiation group (p = 0001). AAM had a higher median prostate-specific antigen (PSA) than CM (9.78 ng/ml vs. 8.0 ng/ml, p = 0.01). Thirty-three percent of AAM had a pretreatment PSA greater than 15 ng/ml compared to 20% of CM (p = 0.00001). Disease-free survival (DFS) by race was equivalent at 36 months, 81% for CM and 77% for AAM (p = NS). For patients with PSA < or =15, DFS rates were 87% and 85% for CM and AAM, respectively. DFS rates for patients with PSA >15 were 61% for CM and 64% for AAM (p = NS). Significant prognostic factors on multivariate analysis included pretreatment PSA (p = 0.0001) and Gleason score (p = 0.0001).

CONCLUSION

Race does not appear to adversely affect biochemical disease-free survival in males treated for early-stage prostate cancer. African-American males with early-stage prostate cancer should expect similar biochemical disease-free survival rates to those seen in Caucasian males.

Racial differences in prostate cancer related to loss of heterozygosity on chromosome 8p12-23

PURPOSE

To determine if there is a racial difference in prostate cancer related to loss of heterozygosity (LOH) on chromosome 8p12-23, the region most frequently altered in prostate cancer.

METHODS AND MATERIALS

A total of 51 prostate cancer patients, consisting of 23 African Americans and 28 Caucasians, were included in this study. All patients underwent radical prostatectomy, and patients in the two racial subgroups were matched for median serum PSA, Gleason score, and pathological stage of cancer. Paired normal prostate and cancer tissue DNA was isolated and amplified with 13 polymorphic markers mapped to 8p12-23 by radiolabeled polymerase chain reaction. The amplified products were resolved by polyacrylamide gel electrophoresis, autoradiographed, and analyzed for allelic losses.

RESULTS

The overall incidence of LOH at 8p12-23 was 53%, and 16% showed homozygous deletions. The incidence of LOH in Caucasians was 68% compared to 35% in African Americans. On univariate (p = 0.02) and multivariate logistic regression analysis (p = 0.02), only Caucasian race was a significant predictor for LOH. The other clinicopathologic parameters did not have any significant effect on incidence of LOH.

CONCLUSION

These results highlight the independent influence of Caucasian race on incidence of LOH at 8p12-23, and suggest that genetic differences at specific tumor suppressor loci may be a factor responsible for racial variations observed in prostate cancer.

Prostate-specific antigen to predict outcome of external beam radiation for prostate cancer: Walter Reed Army Medical Center experience, 1988-1995

OBJECTIVES

To assess the ability of pretreatment and post-treatment prostate-specific antigen (PSA) measurements, clinical tumor stage, tumor grade, Gleason sum, race, age, and radiation dose to predict the recurrence of prostate cancer following external beam radiation therapy (XRT) since the introduction of PSA as a tumor marker at one tertiary care center.

METHODS

The recurrence of prostate cancer among 371 evaluable patients of 389 patients treated with XRT at Walter Reed Army Medical Center was analyzed using Kaplan-Meier survival methodology and Cox multivariable regression models. Serologic (PSA) recurrence was determined using three consecutive rises in PSA after a nadir value. Clinical recurrence was defined as local recurrence (palpable or positive biopsy) and/or distant (radiographically evident) recurrence. Mean and median follow-up is 40.2 and 39.4 months, respectively (range 3.0 to 89.5), and minimum follow-up is 18 months for patients who were alive at the time of analysis. No patient received adjuvant hormonal therapy. Potential prognostic factors evaluated are pretreatment PSA, PSA nadir, age, race, clinical tumor stage, tumor grade, Gleason sum, and radiation dose.

RESULTS

Of the 371 evaluable patients, 125 had disease recurrence. The Kaplan-Meier 5-year disease-free survival (DFS) rates for significant pretreatment variables in univariate analyses are as follows: pretreatment PSA less than 4 (79%), 4.1 to 10 (67%), 10.1 to 20 (57%), 20.1 to 50 (27%), and more than 50 (0%); for clinical tumor Stage T1a-T1c (84%), T2a-T2c (51 %), and T3-T4 (29%); for tumor grade well (58%), moderate (58%), and poor (30%). Four-year DFS rates for Gleason sum are 2 to 4 (82%), 5 (72%), 6 (56%), and 7 to 10 (48%). In multivariable Cox regression analysis with backward elimination of nonsignificant variables, age, race, tumor grade, and radiation dose were eliminated, leaving pretreatment PSA, clinical tumor stage, and Gleason sum as significant prognostic factors. Analysis of a Cox model that included nadir PSA as a time-dependent variable showed it to be the strongest prognostic factor variable in the analysis.

CONCLUSIONS

XRT remains a suitable treatment modality for patients with pretreatment PSA less than 20.0, clinical tumor Stages T1-T2, and Gleason sum 2 to 6 prostate cancer. Patients achieving a nadir value less than 0.5 have more durable treatment outcomes.

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.

Predicting the outcome of radiotherapy for prostate carcinoma: a model-building strategy

BACKGROUND

Clinical research of prostate carcinoma could be enhanced by models that allow early and reliable prediction of outcome. In this study, the authors describe a model-building strategy and compare different models.

METHODS

The sample population was comprised of 158 patients treated definitively with radiotherapy. Univariate and multivariate logistic regression analyses were conducted to identify prognostic factors and select the best predictive model. Variables included age, race, method of diagnosis (needle biopsy vs. transurethral resection of the prostate), stage, grade, pretreatment prostate specific antigen (PSA), in-treatment PSA (PSA(tx)), posttreatment PSA (PSA(post)), and nadir PSA. The following indices were used to compare discriminatory power: log-likelihood function, Akaike information criterion, the generalized coefficient of determination, and the area under the receiver operating characteristic curve.

RESULTS

At last follow-up, 49 patients (31%) had recurrence of carcinoma. By univariate analysis, the failure rate was significantly higher in patients with advanced stage, higher grade, higher pretherapy PSA, and nadir PSA > 1 ng/mL (P < 0.0001). Pretherapy PSA was associated significantly with stage, age, and nadir PSA (P = 0.001, P = 0.001, and P = 0.001, respectively). All PSA measurements were significantly interrelated. Nadir PSA was the most predictive variable. Significant gains (P = 0.01) in predictive power were derived from inclusion of PSA(tx), but not PSA (post). Age, race, stage, grade, and method of diagnosis contributed predictive power in addition to that derived from PSA levels (P = 0.01, log-likelihood test). The authors' model of choice predicts outcome with an overall correctness, sensitivity, specificity, and false-negative rate of 81.8%, 87.2%, 79.6%, and 12.8%, respectively.

CONCLUSIONS

Applying the strategy described, a model was selected that allowed accurate prediction of failure shortly after the completion of therapy.

Genetic predisposition to prostate cancer: possible explanations for ethnic differences in risk

BACKGROUND

It seems unlikely that the large ethnic differences in prostate cancer risk can be explained completely by ethnic differences in diet or other lifestyle characteristics. Instead, the differences may be due to ethnic variation in endogenous factors, such as androgen metabolism or inherited susceptibility.

METHODS

We have reviewed the literature for evidence and support of ethnic variation in genetic susceptibility to prostate cancer as a reason for the ethnic differences in rates.

RESULTS

We distinguish two types of ethnic variation: 1) variation in the prevalence of certain alleles of specific genes that confer modestly increased risk. Such variation might be reflected in ethnic differences in serum levels of androgens, their metabolites, or indicators of metabolism in the prostate; 2) variation in the prevalence of rare germline mutations conferring substantially increased risk. Such variation would be reflected in ethnic differences in familial aggregation of prostate cancer. We discuss the evidence in support of each of these two possibilities.

CONCLUSIONS

Ethnic variation in polymorphic alleles of genes associated with modest fluctuations in risk could explain a large proportion of the ethnic difference in cancer risk. In contrast, rare mutations associated with substantially increased risk are likely to account for a smaller fraction of these differences.

Race and the histologic grade of prostate cancer

We collected data on the histologic grade, stage, and age at diagnosis of 4,114 cases of prostate cancer (1,380 blacks, and 2,734 whites) in the Chicago area. The relationship between histologic grade (high = poorly or undifferentiated vs. low = well or moderately differentiated) and race (black vs. white) was examined using logistic regression. After adjusting for stage (localized, regional, and distant), the odds of high histologic grade prostate cancer in blacks compared to whites equaled 1.7 (95% CI [1.4, 2.0], P < 0.0001). These data suggest that blacks have a significantly higher burden of high histologic grade prostate cancer than whites, even after adjustment for stage at presentation. This higher burden may explain, in part, their higher mortality rate from prostate cancer given the U.S. black vs. white difference in prostate cancer mortality of a similar magnitude.