The North Carolina-Louisiana Prostate Cancer Project (PCaP): methods and design of a multidisciplinary population-based cohort study of racial differences in prostate cancer outcomes

Cigarette smoking and prostate cancer aggressiveness among African and European American men

PURPOSE

Smoking is a modifiable lifestyle factor that has not been established as a prostate cancer risk factor, nor emphasized in prostate cancer prevention. Studies have shown that African American (AA) smokers have a poorer cancer prognosis than European Americans (EAs), while having a lower prevalence of heavy smoking. We examined the relationship between cigarette smoking and prostate cancer aggressiveness and assessed racial differences in smoking habits on the probability of high-aggressive prostate cancer.

METHODS

Using data from the North Carolina-Louisiana Prostate Cancer Project (n = 1,279), prostate cancer aggressiveness was defined as high or low based on Gleason scores, serum prostate-specific antigen levels, and tumor stage. Cigarette smoking was categorized as current, former, or never smokers. Multivariable logistic regression was used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Self-reported current (OR = 1.99; 95% CI 1.30-3.06) smoking was associated with high-aggressive prostate cancer relative to never smokers. When stratified by self-reported race, the odds of having high-aggressive cancer increased among AA current (OR = 3.58; 95% CI 2.04-6.28) and former smokers (OR = 2.21; 95% CI 1.38-3.53) compared to AA never smokers, but the odds were diminished among the EA stratum (Pself-reported race x smoking status = 0.003).

CONCLUSION

Cigarette smoking is associated with prostate cancer aggressiveness, a relationship modulated by self-reported race. Future research is needed to investigate types of cigarettes smoked and metabolic differences that may be contributing to the racial disparities observed.

The impact of marital status on tumor aggressiveness, treatment, and screening among black and white men diagnosed with prostate cancer

PURPOSE

To examine the association of marital status with prostate cancer outcomes in a racially-diverse cohort.

METHODS

The study population consisted of men (1010 Black; 1070 White) with incident prostate cancer from the baseline North Carolina-Louisiana Prostate Cancer (PCaP) cohort. Marital status at time of diagnosis and screening history were determined by self-report. The binary measure of marital status was defined as married (including living as married) vs. not married (never married, divorced/separated, or widowed). High-aggressive tumors were defined using a composite measure of PSA, Gleason Score, and stage. Definitive treatment was defined as receipt of radical prostatectomy or radiation. Multivariable logistic regression was used to examine the association of marital status with (1) high-aggressive tumors, (2) receipt of definitive treatment, and (3) screening history among Black and White men with prostate cancer.

RESULTS

Black men were less likely to be married than White men (68.1% vs. 83.6%). Not being married (vs. married) was associated with increased odds of high-aggressive tumors in the overall study population (adjusted Odds Ratio (aOR): 1.56; 95% Confidence Interval (CI): 1.20-2.02) and both Black and White men in race-stratified analyses. Unmarried men were less likely to receive definitive treatment in the overall study population (aOR: 0.68; 95% CI: 0.54-0.85). In race-stratified analyses, unmarried Black men were less likely to receive definitive treatment. Both unmarried Black and White men were less likely to have a history of prostate cancer screening than married men.

CONCLUSION

Lower rates of marriage among Black men might signal decreased support for treatment decision-making, symptom management, and caregiver support which could potentially contribute to prostate cancer disparities.

Interactions of SNPs in Folate Metabolism Related Genes on Prostate Cancer Aggressiveness in European Americans and African Americans

Background: Studies showed that folate and related single nucleotide polymorphisms (SNPs) could predict prostate cancer (PCa) risk. However, little is known about the interactions of folate-related SNPs associated with PCa aggressiveness. The study’s objective is to evaluate SNP–SNP interactions among the DHFR 19-bp polymorphism and 10 SNPs in folate metabolism and the one-carbon metabolism pathway associated with PCa aggressiveness. Methods: We evaluated 1294 PCa patients, including 690 European Americans (EAs) and 604 African Americans (AAs). Both individual SNP effects and pairwise SNP–SNP interactions were analyzed. Results: None of the 11 individual polymorphisms were significant for EAs and AAs. Three SNP–SNP interaction pairs can predict PCa aggressiveness with a medium to large effect size. For the EA PCa patients, the interaction between rs1801133 (MTHFR) and rs2236225 (MTHFD1), and rs1801131 (MTHFR) and rs7587117 (SLC4A5) were significantly associated with aggressive PCa. For the AA PCa patients, the interaction of DHFR-19bp polymorphism and rs4652 (LGALS3) was significantly associated with aggressive PCa. Conclusions: These SNP–SNP interactions in the folate metabolism-related genes have a larger impact than SNP individual effects on tumor aggressiveness for EA and AA PCa patients. These findings can provide valuable information for potential biological mechanisms of PCa aggressiveness.

Prostate cancer aggressiveness and financial toxicity among prostate cancer patients

INTRODUCTION

Financial toxicity (FT) is a growing concern among cancer survivors that adversely affects the quality of life and survival. Individuals diagnosed with aggressive cancers are often at a greater risk of experiencing FT. The objectives of this study were to estimate FT among prostate cancer (PCa) survivors after 10-15 years of diagnosis, assess the relationship between PCa aggressiveness at diagnosis and FT, and examine whether current cancer treatment status mediates the relationship between PCa aggressiveness and FT.

METHODS

PCa patients enrolled in the North Carolina-Louisiana Prostate Cancer Project (PCaP) were recontacted for long-term follow-up. The prevalence of FT in the PCaP cohort was estimated. FT was estimated using the COmprehensive Score for Financial Toxicity, a validated measure of FT. The direct effect of PCa aggressiveness and an indirect effect through current cancer treatment on FT was examined using causal mediation analysis.

RESULTS

More than one-third of PCa patients reported experiencing FT. PCa aggressiveness was significantly independently associated with high FT; high aggressive PCa at diagnosis had more than twice the risk of experiencing FT than those with low or intermediate aggressive PCa (adjusted odds ratio [aOR] = 2.13, 95% CI = 1.14-3.96). The proportion of the effect of PCa aggressiveness on FT, mediated by treatment status, was 10%, however, the adjusted odds ratio did not indicate significant evidence of mediation by treatment status (aOR = 1.05, 95% CI = 0.95-1.20).

CONCLUSIONS

Aggressive PCa was associated with high FT. Future studies should collect more information about the characteristics of men with high FT and identify additional risk factors of FT.

Using health insurance claims data to assess long-term disease progression in a prostate cancer cohort

BACKGROUND

Long-term population-based cohort studies of men diagnosed with prostate cancer are limited. However, adverse outcomes can occur many years after treatment. Herein, we aim to assess the utility of using claims data to identify prostate cancer progression 10-15 years after diagnosis.

METHODS

The study population was derived from the North Carolina-Louisiana Prostate Cancer Project (PCaP). PCaP-North Carolina (NC) included 1031 men diagnosed with prostate cancer from 2004 to 2009. An initial follow-up with a survey and manual medical record abstraction occurred from 2008 to 2011 (Follow-up 1). Herein, we extended this follow-up with linkage to healthcare claims data from North Carolina (2011-2017) and a second, supplementary 10-year follow-up survey (2018-2020) (Follow-up 2). Vital statistics data also were utilized. Long-term oncological progression was determined using these data sources in combination with expert clinical input.

RESULTS

Among the 1031 baseline PCaP-NC participants, 652 were linked to medical claims. Forty-two percent of the men had insurance coverage for the entire 72 months of follow-up. In addition, 275 baseline participants completed the supplementary 10-year follow-up survey. Using all sources of follow-up data, we identified a progression event in 259 of 1031 (25%) men with more than 10 years of follow-up data after diagnosis.

CONCLUSIONS

Understanding long-term clinical outcomes is essential for improving the lives of prostate cancer survivors. However, access and utility of long-term clinical outcomes with claims alone remain a challenge due to individualized agreements required with each insurer for data access, lack of detailed clinical information, and gaps in insurance coverage. We were able to utilize claims data to determine long-term progression due to several unique advantages that included the availability of detailed baseline clinical characteristics and treatments, detailed manually abstracted clinical data at 5 years of follow-up, vital statistics data, and a supplementary 10-year follow-up survey.

Deconstructing, Addressing, and Eliminating Racial and Ethnic Inequities in Prostate Cancer Care

CONTEXT

Men of African ancestry have demonstrated markedly higher rates of prostate cancer mortality than men of other races and ethnicities around the world. In fact, the highest rates of prostate cancer mortality worldwide are found in the Caribbean and Sub-Saharan West Africa, and among men of African descent in the USA. Addressing this inequity in prostate cancer care and outcomes requires a focused research approach that creates durable solutions to address the structural, social, environmental, and health factors that create racial disparities in care and outcomes.

OBJECTIVE

To introduce a conceptual model for evaluating racial inequities in prostate cancer care to facilitate the development of translational research studies and interventions.

EVIDENCE ACQUISITION

A collaborative review of literature relevant to racial inequities in prostate cancer care and outcomes was performed. Existing literature was used to highlight various components of the conceptual model to inform future research and interventions toward equitable care and outcomes.

EVIDENCE SYNTHESIS

Racial inequities in prostate cancer outcomes are driven by a series of structural and social determinants of health that impact exposures, mediators, and outcomes. Social determinants of equity, such as laws/policies, economic systems, and structural racism, affect the inequitable access to environmental and neighborhood exposures, in addition to health care access. Although the incidence disparity remains problematic, various studies have demonstrated parity in outcomes when social and health factors, such as access to equitable care, are normalized. Few studies have tested interventions to reduce inequities in prostate cancer among Black men.

CONCLUSIONS

Worldwide, men of African ancestry demonstrate worse outcomes in prostate cancer, a phenomenon driven largely by social factors that inform biologic, environmental, and health care risks. A conceptual model was presented that organizes the many factors that influence prostate cancer incidence and mortality. Within that framework, we must understand the current state of inequities in clinical prostate cancer practice, the optimal state of what equitable practice would be, and how achieving equity in prostate cancer care balances costs, benefits, and harms. More robust characterization of the sources of prostate cancer inequities should inform testing of ambitious and innovative interventions as we work toward equity in care and outcomes.

PATIENT SUMMARY

Men of African ancestry demonstrate the highest rates of prostate cancer mortality, which may be reduced through social interventions. We present a framework for formalizing the identification of the drivers of prostate cancer inequities to facilitate the development of interventions and trials to eradicate them.

Recreational and occupational physical activity in relation to prostate cancer aggressiveness: the North Carolina-Louisiana Prostate Cancer Project (PCaP)

PURPOSE

To examine associations between recreational and occupational physical activity and prostate cancer aggressiveness in a population-based, case-only, incident prostate cancer study.

METHODS

Data were analyzed from the cross-sectional North Carolina-Louisiana Prostate Cancer Project of African-American (n = 1,023) and European-American (n = 1,079) men newly diagnosed with prostate cancer (CaP). High-aggressive CaP was defined as Gleason sum ≥ 8, or prostate-specific antigen > 20 ng/ml, or Gleason sum ≥ 7 and clinical stage T3-T4. Metabolic equivalent tasks (MET) were estimated from self-reported recreational physical activity in the year prior to diagnosis assessed retrospectively via a validated questionnaire and from occupational physical activity based on job titles. Associations between physical activity variables and high-aggressive prostate cancer were estimated using logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for multiple confounders.

RESULTS

There was suggestive evidence that walking for 75-150 min/week for exercise is associated with lower odds of high-aggressive prostate cancer compared to no walking (OR = 0.69, 95% CI 0.47-1.01). Physical activity at the current job was associated with 24% lower odds of high-aggressive prostate cancer (highest vs. lowest tertile OR = 0.76, 95% CI 0.56-1.04). However, total MET-h/week of recreational physical activity and accumulation of high-level physical activity at the longest-held job were not associated with high-aggressive prostate cancer. Results did not vary by race.

CONCLUSIONS

The odds of high-aggressive prostate cancer were lower among men who walk for exercise and those engaged in occupations with high activity levels.

Neighborhood deprivation and risk of mortality among men with prostate cancer: Findings from a long-term follow-up study

BACKGROUND

The overall survival rate of prostate cancer (PCa) has improved over the past decades. However, huge socioeconomic and racial disparities in overall and prostate cancer-specific mortality exist. The neighborhood-level factors including socioeconomic disadvantage and lack of access to care may contribute to disparities in cancer mortality. This study examines the impact of neighborhood deprivation on mortality among PCa survivors.

METHODS

North Carolina-Louisiana Prostate Cancer Project (PCaP) data were used. A total of 2113 men, 1046 AA and 1067 EA, with PCa were included in the analysis. Neighborhood deprivation was measured by the Area Deprivation Index (ADI) at the census block group level using data from the US Census Bureau. Quintiles of ADI were created. Cox proportional hazards and competing risk models with mixed effects were performed to estimate the effect of neighborhood deprivation on all-cause and PCa-specific mortality adjusted for age, race, study site, insurance status, and comorbidities.

RESULTS

Participants living in the most deprived neighborhoods had an increased risk for all-cause mortality (quintiles 4 + 5: adjusted hazard ratio [aHR] = 1.51, 95% confidence interval [CI] = 1.16-1.96) compared to those in the least deprived (quintile 1) neighborhoods. The risk of prostate cancer-specific mortality was also higher among those living in the deprived neighborhoods (quintiles 4 + 5: aHR = 1.90, 95% CI = 1.10-3.50) than those in the least deprived neighborhood.

CONCLUSIONS

The findings suggest neighborhood-level resources or health interventions are essential to improve survival among men with PCa. Additional research should focus on the mechanisms of how the neighborhood environment affects mortality.

Differential Associations of SLCO Transporters with Prostate Cancer Aggressiveness between African Americans and European Americans

BACKGROUND

Androgen receptor signaling is crucial to prostate cancer aggressiveness. Members of the solute carrier family of the organic anion transporting peptides (SLCO) are potential regulators of androgen availability in prostate tissue. It remains unknown whether genetic variations in SLCOs contribute to the differences in prostate cancer aggressiveness in African Americans (AA) and European Americans (EA).

METHODS

SNPs in 11 SLCO members were selected, with addition of 139 potentially functional SNPs and 128 ancestry informative markers. A total of 1,045 SNPs were genotyped and analyzed in 993 AAs and 1,057 EAs from the North Carolina-Louisiana Prostate Cancer Project. Expression and cellular localization of SLCOs were examined using qRT-PCR, IHC, and in situ RNA hybridization in independent sets of prostate cancer cases.

RESULTS

Significant associations with prostate cancer characteristics were found for SNPs in SLCO2A1 and SLCO5A1. The associations differed by race (P _interaction < 0.05). SNPs in SLCO2A1 were associated with reduced tumor aggressiveness and low Gleason score in AAs; whereas, SNPs in SLCO5A1 were associated with high clinical stage in EAs. In prostate tissue, SLCO2A1 and SLCO5A1 were the most expressed SLCOs at the mRNA level and were expressed predominantly in prostate endothelial and epithelial cells at the protein level, respectively.

CONCLUSIONS

SLCO2A1 and SLCO5A1 play important but different roles in prostate cancer aggressiveness in AAs versus EAs.

IMPACT

The finding calls for consideration of racial differences in biomarker studies of prostate cancer and for investigations on functions of SLCO2A1 and SLCO5A1 in prostate cancer.

Understanding the Relationship between Environmental Arsenic and Prostate Cancer Aggressiveness among African-American and European-American Men in North Carolina

High-level exposure to arsenic, a known carcinogen and endocrine disruptor, is associated with prostate cancer (PCa) mortality. Whether low-level exposure is associated with PCa aggressiveness remains unknown. We examined the association between urinary arsenic and PCa aggressiveness among men in North Carolina. This cross-sectional study included 463 African-American and 491 European-American men with newly diagnosed, histologically confirmed prostate adenocarcinoma. PCa aggressiveness was defined as low aggressive (Gleason score < 7, stage = cT1–cT2, and PSA < 10 ng/mL) versus intermediate/high aggressive (all other cases). Total arsenic and arsenical species (inorganic arsenic (iAs^III + iAs^V), arsenobetaine, monomethyl arsenic, and dimethyl arsenic)) and specific gravity were measured in spot urine samples obtained an average of 23.7 weeks after diagnosis. Multivariable logistic regression was used to estimate the covariate-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for PCa aggressiveness in association with arsenic tertiles/quantiles overall and by race. The highest (vs. lowest) tertile of total arsenic was associated with PCa aggressiveness ORs of 1.77 (95% CI = 1.05–2.98) among European-American men, and 0.94 (95% CI = 0.57–1.56) among African-American men (P_Interaction = 0.04). In contrast, total arsenic and arsenical species were not associated with PCa aggressiveness in unstratified models. Low-level arsenic exposure may be associated with PCa aggressiveness among European-Americans, but not among African-Americans.

Identification of Plasma Glycosphingolipids as Potential Biomarkers for Prostate Cancer (PCa) Status

Prostate cancer (PCa) is the most common male cancer and the second leading cause of cancer death in United States men. Controversy continues over the effectiveness of prostate-specific antigen (PSA) for distinguishing aggressive from indolent PCa. There is a critical need for more specific and sensitive biomarkers to detect and distinguish low- versus high-risk PCa cases. Discovery metabolomics were performed utilizing ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) on plasma samples from 159 men with treatment naïve prostate cancer participating in the North Carolina-Louisiana PCa Project to determine if there were metabolites associated with aggressive PCa. Thirty-five identifiable plasma small molecules were associated with PCa aggressiveness, 15 of which were sphingolipids; nine common molecules were present in both African-American and European-American men. The molecules most associated with PCa aggressiveness were glycosphingolipids; levels of trihexosylceramide and tetrahexosylceramide were most closely associated with high-aggressive PCa. The Cancer Genome Atlas was queried to determine gene alterations within glycosphingolipid metabolism that are associated with PCa and other cancers. Genes that encode enzymes associated with the metabolism of glycosphingolipids were altered in 12% of PCa and >30% of lung, uterine, and ovarian cancers. These data suggest that the identified plasma (glyco)sphingolipids should be further validated for their association with aggressive PCa, suggesting that specific sphingolipids may be included in a diagnostic signature for PCa.

Association among plasma 1,25(OH)2 D, ratio of 1,25(OH)2 D to 25(OH)D, and prostate cancer aggressiveness

BACKGROUND

African-American (AA) men tend to present with more aggressive prostate cancer (Gleason score >7) than European-American (EA) men. Vitamin D and its metabolites are implicated in prostate cancer biology with vitamin D deficiency, indicated by its metabolite levels in serum or plasma, usually observed in AA men.

OBJECTIVE

To determine if 1, 25-dihydroxy vitamin D3 [1,25(OH)2 D] plasma levels in AA and EA prostate cancer patients alter the risk of having aggressive prostate cancer.

DESIGN

Research subjects from the North Carolina-Louisiana Prostate Cancer Project (AA n = 435 and EA n = 532) were included. Plasma metabolites 1,25(OH)2 D and 25-hydroxyvitamin D3 [25(OH)D] were measured using liquid chromatography with tandem mass spectrophotometry. Research subjects were classified into low (Gleason sum < 7, stage T1-T2, and Prostate-specific antigen (PSA) < 9 ng/mL) or high (Gleason sum > 8 or Gleason sum = 7 with 4 + 3, or PSA > 20 ng/mL, or Gleason sum = 7 and stage T3-T4) aggressive disease.

RESULTS

Research subjects in the second and third tertiles of plasma levels of 1, 25(OH)2 D had lower odds of high aggressive prostate cancer (AA [ORT2vsT1 : 0.66, 95%CI: 0.39-1.12; ORT3vsT1 : 0.83, 95%CI: 0.49-1.41] and EA [ORT2vsT1 : 0.68, 95%CI: 0.41-1.11; ORT3vsT1 : 0.67, 95%CI: 0.40-1.11]) compared with the first tertile, though confidence intervals included the null. Greater 1,25(OH)2 D/25(OH)D molar ratios were associated with lower odds of high aggressive prostate cancer more evidently in AA (ORQ4vsQ1 : 0.45, CI: 0.24-0.82) than in EA (ORQ4vsQ1 : 0.64, CI: 0.35-1.17) research subjects.

CONCLUSIONS

The 1,25(OH)2 D/25(OH)D molar ratio was associated with decreased risk of high aggressive prostate cancer in AA men, and possibly in EA men. Further studies analyzing vitamin D polymorphisms, vitamin D binding protein levels, and prostatic levels of these metabolites may be useful. These studies may provide a better understanding of the vitamin D pathway and its biological role underlying health disparities in prostate cancer.

Prevalence and predictors of probable depression in prostate cancer survivors

BACKGROUND

The early diagnosis and treatment of depression are cancer care priorities. These priorities are critical for prostate cancer survivors because men rarely seek mental health care. However, little is known about the epidemiology of depression in this patient population. The goal of this study was to describe the prevalence and predictors of probable depression in prostate cancer survivors.

METHODS

The data were from a population-based cohort of North Carolinian prostate cancer survivors who were enrolled from 2004 to 2007 in the North Carolina-Louisiana Prostate Cancer Project (n = 1031) and were prospectively followed annually from 2008 to 2011 in the Health Care Access and Prostate Cancer Treatment in North Carolina study (n = 805). Generalized estimating equations were used to evaluate an indicator of probable depression (Short Form 12 mental composite score ≤48.9; measured at enrollment and during the annual follow-up) as a function of individual-level characteristics within the longitudinal data set.

RESULTS

The prevalence of probable depression fell from 38% in the year of the cancer diagnosis to 20% 6 to 7 years later. Risk factors for probable depression throughout the study were African American race, unemployment, low annual income, younger age, recency of cancer diagnosis, past depression, comorbidities, treatment decisional regret, and nonadherence to exercise recommendations.

CONCLUSIONS

Depression is a major challenge for prostate cancer survivors, particularly in the first 5 years after the cancer diagnosis. To the authors' knowledge, this is the first study to demonstrate an association between treatment decisional regret and probable depression.

Patterns and predictors of self-reported clinical diagnosis and treatment for depression in prostate cancer survivors

Background

Appropriate depression care is a cancer‐care priority. However, many cancer survivors live with undiagnosed and untreated depression. Prostate cancer survivors may be particularly vulnerable, but little is known about their access to depression care. The goal of this study was to describe patterns and predictors of clinical diagnosis and treatment of depression in prostate cancer survivors.

Methods

Generalized estimating equations were used to evaluate indicators of self‐reported clinical diagnosis and treatment depression as a function of individual‐level characteristics within a longitudinal dataset. The data were from a population‐based cohort of North Carolinian prostate cancer survivors who were enrolled from 2004 to 2007 on the North Carolina‐Louisiana Prostate Cancer Project (N = 1,031), and prospectively followed annually from 2008 to 2011 on the Health Care Access and Prostate Cancer Treatment in North Carolina (N = 805).

Results

The average rate of self‐reported clinical diagnosis of depression was 44% (95% CI: 39%‐49%), which declined from 60% to 40% between prostate cancer diagnosis and 5‐7 years later. Factors associated with lower odds of self‐reported clinical diagnosis of depression include African‐American race, employment, age at enrollment, low education, infrequent primary care visits, and living with a prostate cancer diagnosis for more than 2 years. The average rate of self‐reported depression treatment was 62% (95% CI: 55%‐69%). Factors associated with lower odds of self‐reported depression treatment included employment and living with a prostate cancer diagnosis for 2 or more years.

Conclusion

Prostate cancer survivors experience barriers when in need of depression care.

The association of metformin use with prostate cancer aggressiveness among Black Americans and White Americans in a population-based study

PURPOSE

Metformin has been associated with a reduced incidence of prostate cancer and improved prostate cancer outcomes. However, whether race modifies the association between metformin use and prostate cancer aggressiveness remains uncertain. The association between metformin use and prostate cancer aggressiveness was examined separately in Black Americans (Blacks) and White Americans (Whites).

METHODS

The study population consisted of 305 Black and 195 White research participants with incident prostate cancer and self-reported diabetes from the North Carolina-Louisiana Prostate Cancer Project. High-aggressive prostate cancer was defined using a composite measure of Gleason sum, prostate-specific antigen, and clinical stage. Multivariable logistic regression was used to assess the association between metformin use and high-aggressive prostate cancer at diagnosis, separately among Whites and Blacks, with adjustment for age, screening history, site, education, insurance, and body mass index.

RESULTS

Metformin use was associated positively with high-aggressive prostate cancer in Blacks (OR 2.01; 95% CI 1.05, 3.83). By contrast, a weak inverse association between metformin use and high-aggressive prostate cancer was found in Whites (OR 0.80, 95% CI 0.34, 1.85).

CONCLUSIONS

The association between metformin use and prostate cancer aggressiveness may be modified by race.

Dietary patterns based on the Mediterranean diet and DASH diet are inversely associated with high aggressive prostate cancer in PCaP

BACKGROUND

Several foods and nutrients have been linked to the development of prostate cancer, but the association between healthy dietary patterns and prostate cancer aggressiveness is less studied. The aim of this study was to evaluate the relationship between the Mediterranean diet (MED) and Dietary Approaches to Stop Hypertension (DASH) diet scores and prostate cancer aggressiveness by race.

METHODS

Data from the population-based, case-only North Carolina-Louisiana Prostate Cancer Project (PCaP) were used to examine the association between diet quality, measured by MED and DASH scores, and prostate cancer aggressiveness in 1899 African American (AA) and European American (EA) research subjects. Dietary intake was assessed using a modified National Cancer Institute Diet History Questionnaire. Logistic regression was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for high versus low-intermediate aggressive prostate cancer.

RESULTS

Higher MED scores were inversely associated with high aggressive prostate cancer overall (OR: 0.66; 95% CI: 0.46, 0.95 for high versus low scores); results were similar for AA and EA men. A weaker inverse association between DASH scores and prostate cancer aggressiveness was found (OR: 0.76; 95% CI: 0.55, 1.06).

CONCLUSIONS

Higher diet quality, as represented by a Mediterranean-style diet or DASH diet, may reduce the odds of high aggressive prostate cancer.

Statin use, high cholesterol and prostate cancer progression; results from HCaP-NC

BACKGROUND

Statin use is associated with lower advanced prostate cancer risk and reduced prostate cancer-specific mortality, but prior studies were conducted mainly in white men. We examined the effect of statin use on risk of prostate cancer progression in a population-based, minority-enriched cohort.

METHODS

We used data from prostate cancer cases (45% African American) diagnosed between 2004 and 2007 who participated in the Health Care Access and Prostate Cancer Treatment in North Carolina cohort (HCaP-NC). We abstracted statin use at diagnosis. Men reported if they had ever been diagnosed with high cholesterol. Multivariable Cox proportional hazards analysis was used to examine associations between statin use and risk of prostate cancer progression (biochemical recurrence or secondary treatment), overall and by race. In secondary analysis, we examined the association between high cholesterol and risk of progression, overall, and by statin use.

RESULTS

Of 669 men, 244 (36%) were statin users at diagnosis. During 3.8 years median follow-up, 138 men experienced prostate cancer progression. There was no association between statin use and risk of progression, either overall (HR 1.03; 95%CI 0.72-1.46) or stratified by race. High cholesterol was inversely associated with risk of progression, particularly among statin users (HR 0.43; 95%CI 0.20-0.94; p-interaction = 0.22) and in men with higher perceived access to care (HR 0.57; 95%CI 0.36-0.90; p-interaction = 0.03). Study limitations included a relatively small sample size, short follow-up, and lack of data regarding post diagnosis statin use.

CONCLUSIONS

Statin use at diagnosis was not associated with prostate cancer progression in the population-based, minority-enriched HCaP-NC. Greater healthcare engagement, including actively controlling serum cholesterol, may be linked to better prostate cancer-specific outcomes.

Modelling attrition and nonparticipation in a longitudinal study of prostate cancer

Background

Attrition occurs when a participant fails to respond to one or more study waves. The accumulation of attrition over several waves can lower the sample size and power and create a final sample that could differ in characteristics than those who drop out. The main reason to conduct a longitudinal study is to analyze repeated measures; research subjects who drop out cannot be replaced easily. Our group recently investigated factors affecting nonparticipation (refusal) in the first wave of a population-based study of prostate cancer. In this study we assess factors affecting attrition in the second wave of the same study. We compare factors affecting nonparticipation in the second wave to the ones affecting nonparticipation in the first wave.

Methods

Information available on participants in the first wave was used to model attrition. Different sources of attrition were investigated separately. The overall and race-stratified factors affecting attrition were assessed. Kaplan-Meier survival curve estimates were calculated to assess the impact of follow-up time on participation.

Results

High cancer aggressiveness was the main predictor of attrition due to death or frailty. Higher Charlson Comorbidity Index increased the odds of attrition due to death or frailty only in African Americans (AAs). Young age at diagnosis for AAs and low income for European Americans (EAs) were predictors for attrition due to lost to follow-up. High cancer aggressiveness for AAs, low income for EAs, and lower patient provider communication scores for EAs were predictors for attrition due to refusal. These predictors of nonparticipation were not the same as those in wave 1. For short follow-up time, the participation probability of EAs was higher than that of AAs.

Conclusions

Predictors of attrition can vary depending on the attrition source. Examining overall attrition (combining all sources of attrition under one category) instead of distinguishing among its different sources should be avoided. The factors affecting attrition in one wave can be different in a later wave and should be studied separately.

Frailty and Comorbidities Among Survivors of Adolescent and Young Adult Cancer: A Cross-Sectional Examination of a Hospital-Based Survivorship Cohort

PURPOSE

Cancer survivors are at increased risk for the early development of age-related chronic medical conditions compared with peers without a history of cancer; however, little is known regarding the burden of these conditions among survivors of adolescent and young adult (AYA) cancers. In response, we sought to determine the prevalence of specific comorbidities and frailty among AYAs (15-39 years old at diagnosis) enrolled in a cancer survivorship cohort.

METHODS

Using a cross-sectional survey of a tertiary medical center-based cancer survivorship cohort, we determined the prevalence of specific comorbidities and frailty using the survey-based FRAIL assessment. In separate models adjusting for age, we estimated prevalence ratios (PRs) for the associations between patient characteristics and (1) any comorbidity and (2) frailty or prefrailty using log-binomial models.

RESULTS

We identified 271 AYA cancer survivors, most of whom were 30-39 years old at survey (57%). A majority of survivors (n = 163, 60%) reported having at least one comorbidity with the most common being depression (28%), anxiety (27%), asthma (17%), high cholesterol (15%), and hypertension (15%). Of the 184 AYA survivors at least 1 year from cancer diagnosis, 19 (10%) were classified as frail and 39 (21%) as prefrail. Survivors who were smokers (PR 2.0, 95% confidence interval [CI]: 1.16-3.56); obese (PR 1.7, 95% CI: 1.10-2.55); uninsured (PR 2.7, 95% CI: 1.63-4.59); or who reported comorbid depression or anxiety (PR 2.4, 95% CI: 1.51-3.67) were more likely to be frail or prefrail.

CONCLUSIONS

The prevalence of frailty and comorbidities is high among AYA cancer survivors suggestive of accelerated aging.

eHealth Literacy and Partner Involvement in Treatment Decision Making for Men With Newly Diagnosed Localized Prostate Cancer

PURPOSE/OBJECTIVES

To examine how the eHealth literacy of partners of patients with newly diagnosed prostate cancer affects their involvement in decision making, and to identify the factors that influence their eHealth literacy.
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DESIGN

Cross-sectional exploratory study.
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SETTING

North Carolina.
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SAMPLE

142 partners of men with newly diagnosed localized prostate cancer. 
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METHODS

A telephone survey and descriptive and multiple linear regression analyses were used.
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MAIN RESEARCH VARIABLES

The partners' eHealth literacy, involvement in treatment decision making, and demographics, and the health statuses of the patients and their partners. 
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FINDINGS

Higher levels of eHealth literacy among partners were significantly associated with their involvement in getting a second opinion, their awareness of treatment options, and the size of the social network they relied on for additional information and support for treatment decision making for prostate cancer. The factor influencing eHealth literacy was the partners' access to the Internet for personal use, which explained some of the variance in eHealth literacy.
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CONCLUSIONS

This study described how partners' eHealth literacy influenced their involvement in treatment decision making for prostate cancer and highlighted the influencing factors (i.e., partners' access to the Internet for personal use).
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IMPLICATIONS FOR NURSING

When helping men with prostate cancer and their partners with treatment decision making, nurses need to assess eHealth literacy levels to determine whether nonelectronically based education materials are needed and to provide clear instructions on how to use eHealth resources.

The Association of Diabetes and Obesity With Prostate Cancer Progression: HCaP-NC

BACKGROUND

The role of race in modifying the association among diabetes, obesity, and prostate cancer (CaP) progression is not well studied. We evaluated diabetes and obesity in association with time to CaP progression in White Americans (Whites) and Black Americans (Blacks).

METHODS

Our study sample consisted of 363 White and 284 Black research participants from the Health Care Access and CaP Treatment in North Carolina (HCaP-NC) cohort. The association between self-reported diabetes or obesity and CaP progression (mean follow-up time approximately 5 years) was assessed using Cox proportional hazards modeling, with adjustment for potential confounders. Stratum-specific hazard ratio (HR) estimates for Whites and Blacks were evaluated.

RESULTS

Self-reported diabetes was not associated with CaP progression in the cohort as a whole (HR: 0.86, 95%CI: 0.54, 1.35), or among racially defined groups (Whites, HR: 1.03, 95%CI: 0.50, 2.13 or Blacks, HR: 0.77, 95%CI: 0.43, 1.39). Obesity was positively associated with CaP progression among Whites, in models including (HR: 1.79, 95%CI: 1.08, 2.97), and excluding (HR: 1.80, 95%CI: 1.09, 2.96) diabetes as a covariate. No association was observed between obesity and CaP progression in Blacks or the cohort as whole.

CONCLUSIONS

Self-reported diabetes was not associated with CaP progression In HCaP-NC. Obesity was associated with CaP progression only among White research participants. Prostate 77:878-887, 2017. © 2017 Wiley Periodicals, Inc.

Unit Nonresponse in a Population-Based Study of Prostate Cancer

Low unit response rates can increase bias and compromise study validity. Response rates have continued to fall over the past decade despite all efforts to increase participation. Many factors have been linked to reduced response, yet relatively few studies have employed multivariate approaches to identify characteristics that differentiate respondents from nonrespondents since it is hard to collect information on the latter. We aimed to assess factors contributing to enrollment of prostate cancer (PCa) patients. We combined data from the North Carolina-Louisiana (LA) PCa Project's LA cohort, with additional sources such as US census tract and LA tumor registry data. We included specific analyses focusing on blacks, a group often identified as hard to enroll in health-related research. The ability to study the effect of Hurricane Katrina, which occurred amidst enrollment, as a potential determinant of nonresponse makes our study unique. Older age (≥ 70) for blacks (OR 0.65) and study phase with respect to Hurricane Katrina for both races (OR 0.59 for blacks, OR 0.48 for whites) were significant predictors of participation with lower odds. Neighborhood poverty for whites (OR 1.53) also was a significant predictor of participation, but with higher odds. Among blacks, residence in Orleans parish was associated with lower odds of participation (OR 0.33) before Katrina. The opposite occurred in whites, with lower odds (OR 0.43) after Katrina. Our results overall underscore the importance of tailoring enrollment approaches to specific target population characteristics to confront the challenges posed by nonresponse. Our results also show that recruitment-related factors may change when outside forces bring major alterations to a population's environment and demographics.

The association of diabetes and obesity with prostate cancer aggressiveness among Black Americans and White Americans in a population-based study

PURPOSE

Few studies have investigated the role of race in the association of diabetes and obesity with prostate cancer aggressiveness. Here we evaluate the independent association between diabetes and obesity with prostate cancer aggressiveness in White Americans and Black Americans.

METHODS

Our cross-sectional, case-only study consisted of 1,058 White Americans and 991 Black Americans from the North Carolina-Louisiana Prostate Cancer (PCaP) project. Diabetes status was determined by self-report. Obesity was determined using body mass index and calculated based on anthropometric measurements. High aggressive prostate cancer was defined as Gleason sum ≥8, or prostate-specific antigen >20 ng/ml, or Gleason sum = 7 and clinical stage cT3-cT4. The association between diabetes and obesity with high aggressive prostate cancer at diagnosis was evaluated using multivariable logistic regression and adjusted for potential confounders.

RESULTS

Diabetes was not associated with high aggressive prostate cancer in the overall sample (OR 1.04; 95% CI 0.79, 1.37), White Americans (OR 1.00; 95% CI 0.65, 1.57) or Black Americans (OR 1.07; 95% CI 0.75, 1.53). Obesity, independent of diabetes, was positively associated with high aggressive prostate cancer in White Americans (OR 1.98; 95% CI 1.14, 3.43), but not in the overall sample (OR 1.37; 95% CI 0.99, 1.92) or Black Americans (OR 1.09; 95% CI 0.71, 1.67).

CONCLUSIONS

Diabetes was not associated with prostate cancer aggressiveness, overall, or in either race group. Obesity, independent of diabetes, was associated with high aggressive prostate cancer only in White Americans.

Carotenoid intake and adipose tissue carotenoid levels in relation to prostate cancer aggressiveness among African-American and European-American men in the North Carolina-Louisiana prostate cancer project (PCaP)

BACKGROUND

Associations between carotenoid intake and prostate cancer (CaP) incidence have varied across studies. This may result from combining indolent with aggressive disease in most studies. This study examined whether carotenoid intake and adipose tissue carotenoid levels were inversely associated with CaP aggressiveness.

METHODS

Data on African-American (AA, n = 1,023) and European-American (EA, n = 1,079) men with incident CaP from North Carolina and Louisiana were analyzed. Dietary carotenoid intake was assessed using a detailed-food frequency questionnaire (FFQ), and abdominal adipose tissue samples were analyzed for carotenoid concentrations using high-performance liquid chromatography. Multivariable logistic regression was used in race-stratified analyses to calculate odds ratios (ORs) and 95% confidence intervals (95%CI) comparing high aggressive CaP with low/intermediate aggressive CaP.

RESULTS

Carotenoid intake differed significantly between AAs and EAs, which included higher intake of lycopene among EAs and higher β-cryptoxanthin intake among AAs. Comparing the highest and lowest tertiles, dietary lycopene was associated inversely with high aggressive CaP among EAs (OR = 0.55, 95%CI: 0.34-0.89, Ptrend  = 0.02), while an inverse association was observed between dietary β-cryptoxanthin intake and high aggressive CaP among AAs (OR = 0.56, 95%CI: 0.36-0.87, Ptrend  = 0.01). Adipose tissue α-carotene and lycopene (cis + trans) concentrations were higher among EAs than AAs, and marginally significant inverse linear trends were observed for adipose α-carotene (Ptrend  = 0.07) and lycopene (Ptrend  = 0.11), and CaP aggressiveness among EAs only.

CONCLUSIONS

These results suggest that diets high in lycopene and β-cryptoxanthin may protect against aggressive CaP among EAs and AAs, respectively. Differences in dietary behaviors may explain the observed racial differences in associations. Prostate 76:1053-1066, 2016. © 2016 Wiley Periodicals, Inc.

Dietary Total Antioxidant Capacity is Inversely Associated with Prostate Cancer Aggressiveness in a Population-Based Study

The purpose of this study was to determine the relationship between total antioxidant capacity (TAC) from diet and supplements and prostate cancer aggressiveness among 855 African Americans (AA) and 945 European Americans (EA) in the North Carolina-Louisiana Prostate Cancer Project (PCaP). Cases were classified as either high aggressive, low aggressive, or intermediate aggressive. TAC was calculated from the vitamin C equivalent antioxidant capacity of 42 antioxidants measured via food frequency questionnaire. EA reported greater dietary TAC from diet and supplements combined (P < 0.0001). In both minimally and fully adjusted logistic regression models, TAC from diet and supplements combined was associated with a reduced odds of high aggressive prostate cancer in all men, AA and EA: odds ratios for highest vs. lowest level (>1500 vs. <500 mg vitamin C equivalent/day): 0.31 [95% confidence interval (CI): 0.15, 0.67; P-trend < 0.01], 0.28 (95% CI: 0.08, 0.96; P-trend < 0.001), and 0.36 (95% CI: 0.15, 0.86; P-trend = 0.58), respectively. These associations did not appear to differ between AA and EA. These data suggest that greater intake of antioxidants is associated with less aggressive prostate cancer. Additional research is needed to confirm these results and determine the underlying mechanisms.

Intake of dietary antioxidants is inversely associated with biomarkers of oxidative stress among men with prostate cancer

Prostate cancer is the most common non-cutaneous cancer and the second leading cause of cancer-related mortality among men in the USA. Growing evidence suggests that oxidative stress is involved in the development and progression of prostate cancer. In this study, the association between antioxidants from diet and supplements and biomarkers of oxidative stress in blood (n 278), urine (n 298) and prostate tissue (n 55) were determined among men from the North Carolina-Louisiana Prostate Cancer Project. The association between antioxidant intake and oxidative stress biomarkers in blood and urine was determined using linear regression, adjusting for age, race, prostate cancer aggressiveness and smoking status. Greater antioxidant intake was found to be associated with lower urinary 8-isoprostane concentrations, with a 10% increase in antioxidant intake corresponding to an unadjusted 1·1% decrease in urinary 8-isoprostane levels (95% CI -1·7, -0·3%; P value<0·01) and an adjusted 0·6% decrease (95% CI -1·4, 0·2%; P value=0·16). In benign prostate tissue, thioredoxin 1 was inversely associated with antioxidant intake (P=0·02). No significant associations were found for other blood or urinary biomarkers or for malignant prostate tissue. These results indicate that antioxidant intake may be associated with less oxidative stress among men diagnosed with prostate cancer.

Dietary, supplement, and adipose tissue tocopherol levels in relation to prostate cancer aggressiveness among African and European Americans: The North Carolina-Louisiana Prostate Cancer Project (PCaP)

BACKGROUND

Controversies remain over the safety and efficacy of vitamin E (i.e., α-tocopherol) supplementation use for the prevention of prostate cancer (CaP); however, associations of different tocopherol forms and CaP aggressiveness have yet to be examined.

METHODS

This study examined whether food intake of tocopherols, vitamin E supplement use, and adipose tissue biomarkers of tocopherol were associated with CaP aggressiveness among African-American (AA, n = 1,023) and European-American (EA, n = 1,079) men diagnosed with incident CaP. Dietary tocopherols were estimated from a food frequency questionnaire, supplement use from questionnaire/inventory, and biomarkers from abdominal adipose samples measured using high-performance liquid chromatography. Odds ratios (ORs) and 95% confidence intervals (95%CIs) were estimated from logistic regression comparing high-aggressive CaP to low/intermediate aggressive CaP, adjusting for covariates.

RESULTS

Dietary intakes of α-and δ-tocopherol were related inversely to CaP aggressiveness among EAs [OR (95%CI), highest versus lowest quartile: α-tocopherol, 0.34 (0.17-0.69), P(trend)  = 0.006; δ-tocopherol, 0.45 (0.21-0.95) P(trend)  = 0.007]. Inverse associations between dietary and supplemental α-tocopherol and CaP aggressiveness were observed among AAs, though these did not reach statistical significance [OR (95%CI), highest versus lowest quartile: dietary α-tocopherol, 0.58 (0.28-1.19), P(trend)  = 0.20; supplemental α-tocopherol, 0.64 (0.31-1.21) P(trend)  = 0.15]. No significant association was observed between adipose tocopherol levels and CaP aggressiveness [OR (95%CI), highest versus lowest quartiles of α-tocopherol for EAs 1.43 (0.66-3.11) and AAs 0.66 (0.27-1.62)].

CONCLUSIONS

The inverse associations observed between dietary sources of tocopherols and CaP aggressiveness suggests a beneficial role of food sources of these tocopherols in CaP aggressiveness.

Thioredoxin 1 in Prostate Tissue Is Associated with Gleason Score, Erythrocyte Antioxidant Enzyme Activity, and Dietary Antioxidants

Background. Prostate cancer is the most common noncutaneous cancer and second leading cause of cancer-related mortality in men in the US. Growing evidence suggests that oxidative stress is involved in prostate cancer. Methods. In this study, thioredoxin 1 (Trx 1), an enzyme and subcellular indicator of redox status, was measured in prostate biopsy tissue from 55 men from the North Carolina-Louisiana Prostate Cancer Project. A pathologist blindly scored levels of Trx 1. The association between Trx 1 and the Gleason score, erythrocyte antioxidant enzyme activity, and dietary antioxidant intake was determined using Fisher's exact test. Results. Trx 1 levels in benign prostate tissue in men with incident prostate cancer were positively associated with the Gleason score (P = 0.01) and inversely associated with dietary antioxidant intake (P = 0.03). In prostate cancer tissue, Trx 1 levels were associated with erythrocyte glutathione peroxidase activity (P = 0.01). No association was found for other erythrocyte enzymes. Greater Gleason score of malignant tissue corresponds to a greater difference in Trx 1 levels between malignant and benign tissue (P = 0.04). Conclusion. These results suggest that the redox status of prostate tissue is associated with prostate cancer grade and both endogenous and exogenous antioxidants.

Genetic variations of the ADIPOQgene and risk of prostate cancer in Chinese Han men

Adiponectin secreted by adipose tissue has been implicated in prostate carcinogenesis. Genetic variations in ADIPOQ are thought to influence the activity of adiponectin, thus relating to cancer occurrence. In this hospital-based case-control study of 917 prostate cancer (PCa) cases and 1036 cancer-free controls, we evaluated the association of single nucleotide polymorphisms in ADIPOQ with risk of PCa and adiponectin levels in Chinese Han men. Variants of ADIPOQ were genotyped by Taqman polymerase chain reaction method. The plasma adiponectin concentrations were measured by enzyme-linked immunosorbent assay (ELISA) in a subset of cases and controls. We found that the ADIPOQ rs3774262 variant AA genotype was associated with both decreased PCa risk [adjusted odds ratio (OR): 0.66, 95% confidence interval (CI) =0.48–0.92] and increased plasma adiponectin levels (P = 0.036 and 0.043), with significant difference by tumor grade, clinical stage, and aggressiveness. A significant interaction between ADIPOQ rs3774262 and body mass index was observed in modifying the risk of PCa (P = 6.7 × 10⁻³). ADIPOQ rs266729 and rs182052 were not related to PCa risk or plasma adiponectin levels. Our data support that ADIPOQ rs3774262 may affect PCa risk in combination with plasma adiponectin levels in Chinese Han men. It may contribute to the molecular basis for the association between obesity and PCa.

Two novel PRKCI polymorphisms and prostate cancer risk in an Eastern Chinese Han population

The atypical protein kinase C (aPKCι), encoded by the PRKCI gene, has been recently found to be a unique human oncoprotein, compared with some other diverse PKC isozymes. Genetic variations in PRKCI have also been reported to be associated with prostate cancer (PCa) risk in Caucasian populations, but no similar studies have been reported for Chinese populations. We genotyped two well-described PRKCI single nucleotide polymorphisms (SNPs) rs546950 and rs4955720 in 1015 PCa patients and 1044 cancer-free controls of Eastern Chinese men. SNPs in the vicinity of those two variants of PRKCI were evaluated using the in silico analysis. Logistic regression was then used to estimate their associations with and interactions in PCa risk. Although no significant main effects were found for the two tested SNPs in the single locus analysis, individuals carrying homozygote wide-type form of these two SNPs had slightly reduced PCa risk (adjusted OR = 0.63, 95% CI = 0.40-0.99, P = 0.045), compared with those carrying any of heterozygous or homozygous variant genotypes. Our results indicated that the two PRKCI SNPs were jointly associated with PCa risk in an Eastern Chinese population. Larger studies with multiethnic groups are warranted to confirm these findings and to explore the role of PRKCI SNPs in the etiology of PCa.

Association between Plasma 25-Hydroxyvitamin D, Ancestry and Aggressive Prostate Cancer among African Americans and European Americans in PCaP

BACKGROUND

African Americans (AAs) have lower circulating 25-hydroxyvitamin D3 [25(OH)D3] concentrations and higher prostate cancer (CaP) aggressiveness than other racial/ethnic groups. The purpose of the current study was to examine the relationship between plasma 25(OH)D3, African ancestry and CaP aggressiveness among AAs and European Americans (EAs).

METHODS

Plasma 25(OH)D3 was measured using LC-MS/MS (Liquid Chromatography Tandem Mass Spectrometry) in 537 AA and 663 EA newly-diagnosed CaP patients from the North Carolina-Louisiana Prostate Cancer Project (PCaP) classified as having either 'high' or 'low' aggressive disease based on clinical stage, Gleason grade and prostate specific antigen at diagnosis. Mean plasma 25(OH)D3 concentrations were compared by proportion of African ancestry. Logistic regression was used to calculate multivariable adjusted odds ratios (OR) and 95% confidence intervals (95%CI) for high aggressive CaP by tertile of plasma 25(OH)D3.

RESULTS

AAs with highest percent African ancestry (>95%) had the lowest mean plasma 25(OH)D3 concentrations. Overall, plasma 25(OH)D3 was associated positively with aggressiveness among AA men, an association that was modified by calcium intake (ORT 3vs.T1: 2.23, 95%CI: 1.26-3.95 among men with low calcium intake, and ORT 3vs.T1: 0.19, 95%CI: 0.05-0.70 among men with high calcium intake). Among EAs, the point estimates of the ORs were <1.0 for the upper tertiles with CIs that included the null.

CONCLUSIONS

Among AAs, plasma 25(OH)D3 was associated positively with CaP aggressiveness among men with low calcium intake and inversely among men with high calcium intake. The clinical significance of circulating concentrations of 25(OH)D3 and interactions with calcium intake in the AA population warrants further study.

Treatment decisional regret among men with prostate cancer: Racial differences and influential factors in the North Carolina Health Access and Prostate Cancer Treatment Project (HCaP-NC)

BACKGROUND

It has been demonstrated that treatment decisional regret affects quality of life in patients with prostate cancer (CaP); however, there are limited studies that identify factors associated with treatment decisional regret, particularly within a racially diverse patient population that has extended follow-up.

METHODS

Logistic regression analysis was used to determine associations between decisional regret and potential predictors in a population-based cohort of 348 African American men and 446 Caucasian American men approximately 3 years after CaP diagnosis.

RESULTS

Of 794 research participants, 12% experienced treatment decisional regret. Decisional regret was associated with androgen-deprivation therapy (odds ratio [OR], 2.1; 95% confidence interval [CI], 1.1-4.0), recent urinary bother (OR, 3.4; 95% CI, 1.6-7.3), satisfaction with understanding potential treatment side effects (very unsatisfied: OR, 13.3; 95% CI, 5.5-32.2; somewhat unsatisfied: OR, 5.0; 95% CI, 2.3-11.2; neutral: OR, 3.8; 95% CI, 1.9-7.6), and CaP treatment effect on the spousal relationship (very affected: OR, 3.9; 95% CI, 2.0-7.6; somewhat affected: OR, 3.1; 95% CI, 1.4-7.3; neutral: OR, 2.4; 95% CI, 1.9-7.6). Younger African Americans were more likely to experience regret than older African Americans (OR, 3.0; 95% CI, 1.1-8.1), and older African Americans were less likely to experience regret than older Caucasian Americans (OR, 0.2; 95% CI, 0.1-0.7).

CONCLUSIONS

Treatment decisional regret remains an important issue in CaP survivors beyond initial treatment. Potential interventions should involve younger African Americans and patient spouses. Increased regret may reflect the unexpected influence of treatment side effects on the patient's everyday life; helping the patient relate potential side effects to his individual situation could improve patient satisfaction.

Associations between patient-provider communication and socio-cultural factors in prostate cancer patients: a cross-sectional evaluation of racial differences

OBJECTIVE

To examine the association between socio-cultural factors and patient-provider communication and related racial differences.

METHODS

Data analysis included 1854 men with prostate cancer from a population-based study. Participants completed an assessment of communication variables, physician trust, perceived racism, religious beliefs, traditional health beliefs, and health literacy. A multi-group structural equation modeling approach was used to address the research aims.

RESULTS

Compared with African Americans, Caucasian Americans had significantly greater mean scores of interpersonal treatment (p<0.01), prostate cancer communication (p<0.001), and physician trust (p<0.001), but lower mean scores of religious beliefs, traditional health beliefs, and perceived racism (all p values <0.001). For both African and Caucasian Americans, better patient-provider communication was associated with more physician trust, less perceived racism, greater religious beliefs (all p-values <0.01), and at least high school education (p<0.05).

CONCLUSION

Socio-cultural factors are associated with patient-provider communication among men with cancer. No evidence supported associations differed by race.

PRACTICE IMPLICATION

To facilitate patient-provider communication during prostate cancer care, providers need to be aware of patient education levels, engage in behaviors that enhance trust, treat patients equally, respect religious beliefs, and reduce the difficulty level of the information.

Admixture mapping of prostate cancer in African Americans participating in the North Carolina-Louisiana Prostate Cancer Project (PCaP)

BACKGROUND

Few genetic risk factors have been uncovered that contribute specifically to the racial disparity in prostate cancer (CaP) observed in African Americans (AA). With the advent of ancestry informative marker (AIM) single nucleotide polymorphism (SNP) panels and powerful genetic strategies such as mapping by admixture linkage disequilibrium (MALD) it is possible to discover genes that underlie ethnic variation in disease risk.

METHODS

One thousand one hundred thirty AA CaP cases enrolled in the North Carolina-Louisiana Prostate Cancer Project (PCaP) were genotyped using a 1,509 AIM SNP panel. MALD was performed using ADMIXMAP to test for linkage between CaP risk and ancestry estimates at each AIM SNP.

RESULTS

The largest increase of African ancestry was observed at marker rs12543473 (P = 0.0011), located on chromosome 8q24.21, and the greatest excess of European ancestry was observed at marker rs10768140 (P = 0.0004) at chromosome 11p13.

CONCLUSIONS

The study confirmed the 8q24 risk loci and identified a novel genomic region on 11p13 that is associated with CaP risk. These findings should be replicated in larger AA populations and combined with fine mapping data to further refine the novel 11p13 CaP risk loci.

The influence of mistrust, racism, religious participation, and access to care on patient satisfaction for African American men: the North Carolina-Louisiana Prostate Cancer Project

OBJECTIVE

The purpose of this study was to explore whether a particular combination of individual characteristics influences patient satisfaction with the health care system among a sample of African American men in North Carolina with prostate cancer. Patient satisfaction may be relevant for improving African American men's use of regular care, thus improving the early detection of prostate cancer and attenuating racial disparities in prostate cancer outcomes.

METHODS

This descriptive correlation study examined relationships of individual characteristics that influence patient satisfaction using data from 505 African American men from North Carolina, who prospectively enrolled in the North Carolina-Louisiana Prostate Cancer Project from September 2004 to November 2007. Analyses consisted of univariate statistics, bivariate analysis, and multiple regression analysis.

RESULTS

The variables selected for the final model were: participation in religious activities, mistrust, racism, and perceived access to care. In this study, both cultural variables, mistrust (p=<.0001, F=95.58) and racism (p=<.002, F=5.59), were significantly negatively associated with patient satisfaction and accounted for the majority of the variability represented by individual characteristics.

CONCLUSION

Mistrust and racism are cultural factors that are extremely important and have been negatively associated with patient satisfaction and decreased desires to utilize health care services for African American men. To overcome barriers in seeking health care services, health care providers need to implement a patient-centered approach by creating a clinical environment that demonstrates cultural competence and eliminating policies, procedures, processes, or personnel that foster mistrust and racism.

The association between calcium channel blocker use and prostate cancer outcome

BACKGROUND

Epidemiological studies indicate that calcium channel blocker (CCB) use is inversely related to prostate cancer (PCa) incidence. The association between CCB use and PCa aggressiveness at the time of radical prostatectomy (RP) and outcome after RP was examined.

METHODS

Medication use, PCa aggressiveness and post-RP outcome were retrieved from a prospectively populated database that contains clinical and outcome for RP patients at Roswell Park Cancer Institute (RPCI) from 1993 to 2010. The database was queried for anti-hypertensive medication use at diagnosis for patients with ≥1 year follow-up. Recurrence was defined using NCCN guidelines. Chi-Square tests assessed the relationship between CCB use and PCa aggressiveness. Cox regression models compared the distribution of progression-free survival (PFS) and overall survival (OS) with adjustment for covariates. Results for association between CCB usage and PCa aggressiveness were validated using data from the population-based North Carolina-Louisiana Prostate Cancer Project (PCaP).

RESULTS

48%, 37%, and 15% of RPCI's RP patients (n = 875) had low, intermediate, and high aggressive PCa, respectively. 104 (11%) had a history of CCB use. Patients taking CCBs were more likely to be older, have a higher BMI and use additional anti-hypertensive medications. Diagnostic PSA levels, PCa aggressiveness, and margin status were similar for CCB users and non-users. PFS and OS did not differ between the two groups. Tumor aggressiveness was associated with PFS. CCB use in the PCaP study population was not associated with PCa aggressiveness.

CONCLUSIONS

CCB use is not associated with PCa aggressiveness at diagnosis, PFS or OS.

Receipt of National Comprehensive Cancer Network guideline-concordant prostate cancer care among African American and Caucasian American men in North Carolina

BACKGROUND

African Americans have a higher incidence of prostate cancer and experience poorer outcomes compared with Caucasian Americans. Racial differences in care are well documented; however, few studies have characterized patients based on their prostate cancer risk category, which is required to differentiate appropriate from inappropriate guideline application.

METHODS

The medical records of a population-based sample of 777 North Carolina men with newly diagnosed prostate cancer were studied to assess the association among patient race, clinical factors, and National Comprehensive Cancer Network (NCCN) guideline-concordant prostate cancer care.

RESULTS

African Americans presented with significantly higher Gleason scores (P = .025) and prostate-specific antigen levels (P = .008) than did Caucasian Americans. However, when clinical T stage was considered as well, difference in overall risk category only approached statistical significance (P = .055). Across risk categories, African Americans were less likely to have surgery (58.1% versus 68.0%, P = .004) and more likely to have radiation (39.0% versus 27.4%, P = .001) compared with Caucasian Americans. However, 83.5% of men received guideline-concordant care within 1 year of diagnosis, which did not differ by race in multivariable analysis (odds ratio = 0.83; 95% confidence interval  = 0.54-1.25). Greater patient-perceived access to care was associated with greater odds of receiving guideline-concordant care (odds ratio = 1.06; 95% confidence interval = 1.01-1.12).

CONCLUSIONS

After controlling for NCCN risk category, there were no racial differences in receipt of guideline-concordant care. Efforts to improve prostate cancer treatment outcomes should focus on improving access to the health care system.

Patient-health care provider communication among patients with newly diagnosed prostate cancer: findings from a population-based survey

OBJECTIVE

To examine the multidimensional concept of patient-health care provider (HCP) communication, its effects on patient satisfaction with oncology care services, and related racial differences.

METHODS

The current analysis draws from a population-based survey sample of 1011 African American and 1034 Caucasian American men with newly diagnosed prostate cancer. The variables of satisfaction with health care services, interpersonal treatment, contextual knowledge of the patient, and prostate cancer communication were analyzed using multiple-group structural equation modeling.

RESULTS

Regardless of race, patient-HCP communication was related positively to interpersonal treatment by the HCP, HCP's contextual knowledge of the patient, and prostate cancer communication. More positive patient-HCP communication was related to more satisfaction with health care services. Racial differences were significant in the relationships between patient-HCP communication and prostate cancer communication.

CONCLUSION

Content and interpersonal relationships are important aspects of patient-HCP communication and affect patient satisfaction with oncologic care for prostate cancer.

PRACTICE IMPLICATIONS

HCPs need to integrate the transfer of information with emotional support and interpersonal connection when they communicate with men with newly diagnosed prostate cancer.

Who makes the decision regarding the treatment of clinically localized prostate cancer--the patient or physician?: results from a population-based study

BACKGROUND

The current study examined how patients' sociodemographic, cancer-related, and subjective affective factors impacted their role in treatment decision-making.

METHODS

The patient sample (N = 788) was taken from a prospective follow-up study of a population-based cohort. Participants included 343 African American and 445 Caucasian-American patients with clinically localized prostate cancer. Multinomial logistic regression was used to investigate relations between the explanatory variables and the nominal 3-level decision-making variable: patient-only, patient-physician shared, and physician-only.

RESULTS

Approximately 41% of patients reported patient-only decision-making, 45% reported shared decision-making, and 13% reported physician-only decision-making. The odds of patient-only over physician-only decision-making were greater for younger men (vs those aged ≥ 65 years) (odds ratio [OR], 1.68; 95% confidence interval [95% CI], 1.03-2.74), and were less for men with high (vs low) cancer aggressiveness (OR,0.29; 95% CI, 0.15-0.55). The odds of shared over physician-only decision-making were less for men with high (vs low) cancer aggressiveness (OR, 0.40; 95% CI, 0.22-0.73). Greater odds of patient-only and shared decision-making also were found to be associated with greater concerns about the physical impact of treatment and having enough time for decision-making and lower scores of receiving advice from others.

CONCLUSIONS

The findings of the current study indicate that, to facilitate a more patient-oriented decision-making process regarding treatment in those with clinically localized prostate cancer, clinicians need to tailor their interventions according to patient age and cancer aggressiveness, help reduce patient concerns and misconceptions regarding the physical impact of treatments, allow sufficient time for patients to consider treatment options, and assist patients in balancing advice and information received from different sources.

Genetic polymorphism and prostate cancer aggressiveness: a case-only study of 1,536 GWAS and candidate SNPs in African-Americans and European-Americans

BACKGROUND

Genome-wide association studies have established a number of replicated single nucleotide polymorphisms (SNPs) for susceptibility to prostate cancer (CaP), but it is unclear whether these susceptibility SNPs are also associated with disease aggressiveness. This study evaluates whether such replication SNPs or other candidate SNPs are associated with CaP aggressiveness in African-American (AA) and European-American (EA) men.

METHODS

A 1,536 SNP panel which included 34 genome-wide association study (GWAS) replication SNPs, 38 flanking SNPs, a set of ancestry informative markers, and SNPs in candidate genes and other areas was genotyped in 1,060 AA and 1,087 EA men with incident CaP from the North Carolina-Louisiana Prostate Cancer Project (PCaP). Tests for association were conducted using ordinal logistic regression with a log-additive genotype model and a 3-category CaP aggressiveness variable.

RESULTS

Four GWAS replication SNPs (rs2660753, rs13254738, rs10090154, rs2735839) and seven flanking SNPs were associated with CaP aggressiveness (P < 0.05) in three genomic regions: One at 3p12 (EA), seven at 8q24 (5 AA, 2 EA), and three at 19q13 at the kallilkrein-related peptidase 3 (KLK3) locus (two AA, one AA and EA). The KLK3 SNPs also were associated with serum prostate-specific antigen (PSA) levels in AA (P < 0.001) but not in EA. A number of the other SNPs showed some evidence of association but none met study-wide significance levels after adjusting for multiple comparisons.

CONCLUSIONS

Some replicated GWAS susceptibility SNPs may play a role in CaP aggressiveness. However, like susceptibility, these associations are not consistent between racial groups.

Intake of grains and dietary fiber and prostate cancer aggressiveness by race

Purpose. To examine the associations among intake of refined grains, whole grains and dietary fiber and aggressiveness of prostate cancer in African Americans (AA, n = 930) and European Americans (EA, n = 993) in a population-based, case-only study (The North Carolina-Louisiana Prostate Cancer Project, PCaP). Methods. Prostate cancer aggressiveness was categorized as high, intermediate or low based on Gleason grade, PSA level and clinical stage. Dietary intake was assessed utilizing the NCI Diet History Questionnaire. Logistic regression (comparing high to intermediate/low aggressive cancers) and polytomous regression with adjustment for potential confounders were used to determine odds of high prostate cancer aggressiveness with intake of refined grains, whole grains and dietary fiber from all sources. Results. An inverse association with aggressive prostate cancer was observed in the 2nd and 3rd tertiles of total fiber intake (OR = 0.70; 95% CI, 0.50–0.97 and OR = 0.61; 95% CI, 0.40–0.93, resp.) as compared to the lowest tertile of intake. In the race-stratified analyses, inverse associations were observed in the 3rd tertile of total fiber intake for EA (OR = 0.44; 95% CI, 0.23–0.87) and the 2nd tertile of intake for AA (OR = 0.57; 95% CI, 0.35–0.95). Conclusions. Dietary fiber intake was inversely associated with aggressive prostate cancer among both AA and EA men.

Serum glutamate levels correlate with Gleason score and glutamate blockade decreases proliferation, migration, and invasion and induces apoptosis in prostate cancer cells

PURPOSE

During glutaminolysis, glutamine is catabolized to glutamate and incorporated into citric acid cycle and lipogenesis. Serum glutamate levels were measured in patients with primary prostate cancer or metastatic castrate-resistant prostate cancer (mCRPCa) to establish clinical relevance. The effect of glutamate deprivation or blockade by metabotropic glutamate receptor 1 (GRM1) antagonists was investigated on prostate cancer cells' growth, migration, and invasion to establish biologic relevance.

EXPERIMENTAL DESIGN

Serum glutamate levels were measured in normal men (n = 60) and patients with primary prostate cancer (n = 197) or mCRPCa (n = 109). GRM1 expression in prostatic tissues was examined using immunohistochemistry (IHC). Cell growth, migration, and invasion were determined using cell cytotoxicity and modified Boyden chamber assays, respectively. Apoptosis was detected using immunoblotting against cleaved caspases, PARP, and γ-H2AX.

RESULTS

Univariate and multivariate analyses showed significantly higher serum glutamate levels in Gleason score ≥ 8 than in the Gleason score ≤ 7 and in African Americans than in the Caucasian Americans. African Americans with mCRPCa had significantly higher serum glutamate levels than those with primary prostate cancer or benign prostate. However, in Caucasian Americans, serum glutamate levels were similar in normal research subjects and patients with mCRPC. IHC showed weak or no expression of GRM1 in luminal acinar epithelial cells of normal or hyperplastic glands but high expression in primary or metastatic prostate cancer tissues. Glutamate deprivation or blockade decreased prostate cancer cells' proliferation, migration, and invasion and led to apoptotic cell death.

CONCLUSIONS

Glutamate expression is mechanistically associated with and may provide a biomarker of prostate cancer aggressiveness.

Patient Satisfaction Influenced by interpersonal treatment and communication for African American men: the North Carolina-Louisiana Prostate Cancer Project (PCaP)

The purpose of this study was to determine if a particular set of health behaviors of health care providers and African American men (AAM) influence patient satisfaction from the AAM's perspective. This descriptive, correlational study consisted of 505 AAM in North Carolina diagnosed with prostate cancer and enrolled in the North Carolina-Louisiana Prostate Cancer Project (PCaP). Analyses consisted of bivariate analyses and multiple regression. Patient-to-provider communication, interpersonal treatment, and provider-to-patient communication accounted for 45% (p ≤ .0001) of the variability in patient satisfaction. Interpersonal treatment (provider focusing on the patient) explained the greatest amount (F = 313.53, R² = .39) of patient satisfaction. Since interpersonal treatment focuses on the patient and demonstrated to be the strongest predictor in patient satisfaction, it is noteworthy to consider the emphasis that should be placed on patient-centered care. In addition, knowing important variables positively affecting patient satisfaction provides useful information for developing appropriate interventions to improve AAM health care experiences.