East meets West: ethnic differences in prostate cancer epidemiology between East Asians and Caucasians

Dietary patterns and prostate cancer risk in Japanese: the Japan Public Health Center-based Prospective Study (JPHC Study)

PURPOSE

The development of prostate cancer may be impacted by environmental factors, including diet. The aim of this study was to evaluate the association between dietary patterns and risk of prostate cancer in a large prospective cohort study among Japanese men.

METHODS

A total of 43,469 men who participated in the Japan Public Health Center-based Prospective Study were followed from 1995 to 1998 to the end of 2012, during which 1,156 cases of prostate cancer were newly identified. Dietary intake was assessed using a validated food frequency questionnaire in the 5-year follow-up survey.

RESULTS

Three major dietary patterns were derived using exploratory factors analysis: prudent, westernized, and traditional dietary patterns. The westernized dietary pattern was associated with a higher risk of total prostate cancer (HR: 1.22; 95% CI 1.00-1.49; p trend = 0.021), localized cancer (HR: 1.24; 95% CI 0.97-1.57; p trend = 0.045), and advanced cancer (HR: 1.23; 95% CI 0.82-1.84; p trend = 0.233). The prudent dietary pattern was associated with a lower risk of total and localized prostate cancer, with respective multivariable HRs for the highest and lowest quintiles of 0.71 (95% CI 0.50-1.02; p trend = 0.037) and 0.63 (95% CI 0.38-1.03; p trend = 0.048) among subjects detected by subjective symptoms. No association was found between the traditional dietary pattern and prostate cancer risk among our subjects.

CONCLUSION

Our results suggest that a western-style diet may lead to a higher risk of prostate cancer in the total population, whereas the prudent diet contributes to a lower risk among subjects detected by subjective symptoms.

Clinical Significance of Peripheral Blood PCA3 Gene Expression in Early Diagnosis of Prostate Cancer

Prostate cancer antigen 3 (PCA3) is one of the most promising genes currently investigated as a specific tumor biomarker for the diagnosis of prostate cancer. The purpose of this study was to investigate PCA3 gene expression in peripheral blood of prostate cancer (PCa) and benign prostate hyperplasia (BPH), and further to assess its clinical significance. We determined the copies of PCA3 mRNA in peripheral blood of PCa and BPH from 115 samples (PCa, n = 78; BPH, n = 37) using a quantitative reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) with TaqMan assay. The sensitivity and specificity of PCA3 for the diagnosis of prostate cancer was compared with that of prostate-specific antigen (PSA) by receiver operating characteristic (ROC) curve analysis. To evaluate the association between PCA mRNA and disease progression, we analyzed PCA3 levels in connection with Gleason score and TNM stage of PCa. The clinical data revealed that expression of PCA3 gene was significantly higher in PCa than in BPH. Moreover, PCA3 mRNA was significantly higher in PCa patients with a Gleason score ≥8 than in those with a Gleason score ≤7 (P < .01). The results showed that the area under the curve (AUC) was 0.790, 0.606, and 0.620 for the copy number of PCA3, PSA level, and significantly free PSA (fPSA) level, respectively. Increased PCA3 in peripheral blood is correlated with PCa, and the detection of PCA3 may significantly reduce adverse screening outcomes. PCA3 gene expression in peripheral blood had a promising clinical application in the early diagnosis of PCa.

Risk of prostate cancer across different racial/ethnic groups in men with diabetes: a retrospective cohort study

AIM

To examine the associations between prostate cancer, diabetes and race/ethnicity.

METHODS

Using administrative data from British Columbia, Canada for the period 1994 to 2012, we identified men aged ≥50 years with and without diabetes. Validated surname algorithms identified men as Chinese, Indian or of other race/ethnicity. Multivariable Cox regression was used to estimate adjusted risks of prostate cancer according to diabetes status and race/ethnicity.

RESULTS

Our cohort of 160 566 men had a mean (sd) age of 64.7 (9.4) years and a median of 9 years' follow-up. The incidence rates of prostate cancer among those with and without diabetes were 177.4 (171.7-183.4) and 216.0 (209.7-222.5) per 1000 person-years, respectively. The incidence among Chinese men was 120.9 (109.2-133.1), among Indian men it was 144.1 (122.8-169.0) and in men of other ethnicity it was 204.8 (200.2-209.5). Diabetes was independently associated with a lower risk of prostate cancer (adjusted hazard ratio 0.82, 95% CI 0.78-0.86), as was Chinese (adjusted hazard ratio 0.54, 95% CI 0.46,0.63) and Indian (adjusted hazard ratio 0.66, 95% CI 0.49,0.89) race/ethnicity; however, there was no statistically significant interaction between diabetes status and race/ethnicity (all P>0.1).

CONCLUSION

Diabetes and Chinese and Indian race/ethnicity were each independently associated with a lower risk of prostate cancer.

Effects of genistein supplementation on genome‑wide DNA methylation and gene expression in patients with localized prostate cancer

Epidemiological studies have shown that dietary compounds have significant effects on prostate carcinogenesis. Among dietary agents, genistein, the major isoflavone in soybean, is of particular interest because high consumption of soy products has been associated with a low incidence of prostate cancer, suggesting a preventive role of genistein in prostate cancer. In spite of numerous studies to understand the effects of genistein on prostate cancer, the mechanisms of action have not been fully elucidated. We investigated the differences in methylation and gene expression levels of prostate specimens from a clinical trial of genistein supplementation prior to prostatectomy using Illumina HumanMethylation450 and Illumina HumanHT-12 v4 Expression BeadChip Microarrays. The present study was a randomized, placebo-controlled, double-blind clinical trial on Norwegian patients who received 30 mg genistein or placebo capsules daily for 3–6 weeks before prostatectomy. Gene expression changes were validated by quantitative PCR (qPCR). Whole genome methylation and expression profiling identified differentially methylated sites and expressed genes between placebo and genistein groups. Differentially regulated genes were involved in developmental processes, stem cell markers, proliferation and transcriptional regulation. Enrichment analysis suggested overall reduction in MYC activity and increased PTEN activity in genistein-treated patients. These findings highlight the effects of genistein on global changes in gene expression in prostate cancer and its effects on molecular pathways involved in prostate tumorigenesis.

Long-term allopurinol use decreases the risk of prostate cancer in patients with gout: a population-based study

BACKGROUND

Clinical observations indicated an increased risk of developing prostate cancer in gout patients. Chronic inflammation is postulated to be one crucial mechanism for prostate carcinogenesis. Allopurinol, a widely used antigout agent, possesses potent anti-inflammation capacity. We elucidated whether allopurinol decreases the risk of prostate cancer in gout patients.

METHODS

We analyzed data retrieved from Taiwan National Health Insurance Database between January 2000 and December 2012. Patients diagnosed with gout during the study period with no history of prostate cancer and who had never used allopurinol were selected. Four allopurinol use cohorts (that is, allopurinol use (>365 days), allopurinol use (181-365 days), allopurinol use (91-180 days) and allopurinol use (31-90 days)) and one cohort without using allopurinol (that is, allopurinol use (No)) were included. The study end point was the diagnosis of new-onset prostate cancer. Multivariable Cox proportional hazards regression and propensity score-adjusted Cox regression models were used to estimate the association between the risk of prostate cancer and allopurinol treatment in gout patients after adjusting for potential confounders.

RESULTS

A total of 25 770 gout patients (aged between 40 and 100 years) were included. Multivariable Cox regression analyses revealed that the risk of developing prostate cancer in the allopurinol use (>365 days) cohort was significantly lower than the allopurinol use (No) cohort (adjusted hazard ratio (HR)=0.64, 95% confidence interval (CI)=0.45-0.9, P=0.011). After propensity score adjustment, the trend remained the same (adjusted HR=0.66, 95% CI=0.46-0.93, P=0.019).

CONCLUSIONS

Long-term (more than 1 year) allopurinol use may associate with a decreased risk of prostate cancer in gout patients.

PSA and Prostate Health Index based prostate cancer screening in a hereditary migration complicated population: implications in precision diagnosis

Precision diagnosis requires specific markers for differential ethnic populations. Prostate-Specific Antigen (PSA) level (threshold of 4ng/ml) has been widely used to screen prostate cancer and as reference of pro-biopsy but false diagnosis frequently occurs. Prostate health Index (PHI) is a new diagnosis marker which combines PSA, free PSA and p2PSA4. Overall the PCa screening database is lacking in Kazakhstani patients. We analyzed the PSA levels and Gleason scores of 222 biopsies collected in 2015 in Almaty area, Kazakhstan approved by institutional ethics board. We found using PSA of 4ng/ml as threshold, only 25.68% of patients have cancer with Gleason score ranged 6-8 and 65.77% of patients have no character of cancer. Moreover, there is no significant correlation between PSA and cancerous (P=0.266) or Gleason grade (P=0.3046) based on pathological biopsy. In addition, PHI is not correlated to prostate cancer (P=0.4301). Our data suggest that false-positive rate is much higher than the correct-positive diagnosis when using PSA as the first screening. Thus in this cohort study, most patients can not get benefit from the PSA screening for precision PCa diagnosis. As Kazakhstani family trees are unique and complicated because of history and migration, the high rate of over diagnosis might be due to the hyperexpression of PSA via heterosis in Eurasian men. Therefore we should be cautious when using pro-biopsy in precision diagnosis for Eurasian prostate cancer patients.

Gleason grade grouping of prostate cancer is of prognostic value in Asian men

AIM

The International Society of Urological Pathology made recommendations for the use of Grade Groups (GG) originally described by Epstein and colleagues over Gleason score (GS) alone in 2014, which was subsequently adopted by the WHO classification in 2016. The majority of studies validating this revision have been in Caucasian populations. We therefore asked whether the new GG system was retrospectively associated with biochemical disease-free survival in a mixed-ethnicity cohort of Asian men.

METHODS

A total of 680 radical prostatectomies (RPs) from 2005 to 2014 were included. GS from initial biopsy and RP were compared and used to allocate cases to GG, defined as: 1 (GS≤6); 2 (GS 3+4=7); 3 (GS 4+3=7); 4 (GS 4+4=8/5+3=8/3+5=8) and 5 (GS 9-10). Biochemical recurrence was defined as two consecutive post-RP prostate-specific antigen (PSA) levels of >0.2 ng/mL after post-RP PSA reaching the nadir of <0.1 ng/mL.

RESULTS

Our data showed that Kaplan-Meier analysis revealed significant differences in biochemical recurrence within Gleason GG based on either biopsy or prostatectomy scoring. Multivariate analysis further confirmed that a higher GG was significantly associated with risk of biochemical recurrence. This GG system had a higher prognostic discrimination for both initial biopsy and RP than GS.

CONCLUSIONS

Our study validates the use of the revised and updated GG system in a mixed-ethnicity population of Asian men. Higher GG was significantly associated with increased risk of biochemical recurrence. We therefore recommend its use to inform clinical management for patients with prostate cancer.

Prostate cancer antigen 3 moderately improves diagnostic accuracy in Chinese patients undergoing first prostate biopsy

Prostate cancer antigen 3 (PCA3) is a biomarker for diagnosing prostate cancer (PCa) identified in the Caucasian population. We evaluated the effectiveness of urinary PCA3 in predicting the biopsy result in 500 men undergoing initial prostate biopsy. The predictive power of the PCA3 score was evaluated by the area under receiver operating characteristic (ROC) curve (AUC) and by decision curve analysis. PCA3 score sufficed to discriminate positive from negative prostate biopsy results but was not correlated with the aggressiveness of PCa. The ROC analysis showed a higher AUC for the PCA3 score than %fPSA (0.750 vs 0.622, P = 0.046) in patients with a PSA of 4.0–10.0 ng ml⁻¹, but the PCA3-based model is not significantly better than the base model. Decision curve analysis indicates the PCA3-based model was superior to the base model with a higher net benefit for almost all threshold probabilities, especially the threshold probabilities of 25%–40% in patients with a PSA of 4.0–10.0 ng ml⁻¹. However, the AUC of the PCA3 score (0.712) is not superior to %fPSA (0.698) or PSAD (0.773) in patients with a PSA >10.0 ng ml⁻¹. Our results confirmed that the RT-PCR-based PCA3 test moderately improved diagnostic accuracy in Chinese patients undergoing first prostate biopsy with a PSA of 4.0–10.0 ng ml⁻¹.

Epigenetic basis of cancer health disparities: Looking beyond genetic differences

Despite efforts at various levels, racial health disparities still exist in cancer patients. These inequalities in incidence and/or clinical outcome can only be explained by a multitude of factors, with genetic basis being one of them. Several investigations have provided convincing evidence to support epigenetic regulation of cancer-associated genes, which results in the differential transcriptome and proteome, and may be linked to a pre-disposition of individuals of certain race/ethnicity to early or more aggressive cancers. Recent technological advancements and the ability to quickly analyze whole genome have aided in these efforts, and owing to their relatively easy detection, methylation events are much well-characterized, than the acetylation events, across human populations. The early trend of investigating a pre-determined set of genes for differential epigenetic regulation is paving way for more unbiased screening. This review summarizes our current understanding of the epigenetic events that have been tied to the racial differences in cancer incidence and mortality. A better understanding of the epigenetics of racial diversity holds promise for the design and execution of novel strategies targeting the human epigenome for reducing the disparity gaps.

Estimation of heritability for nine common cancers using data from genome-wide association studies in Chinese population

The familial aggregation indicated the inheritance of cancer risk. Recent genome-wide association studies (GWASs) have identified a number of common single-nucleotide polymorphisms (SNPs). Following heritability analyses have shown that SNPs could explain a moderate amount of variance for different cancer phenotypes among Caucasians. However, little information was available in Chinese population. We performed a genome-wide complex trait analysis for common cancers at nine anatomical sites in Chinese population (14,629 cancer cases vs. 17,554 controls) and estimated the heritability of these cancers based on the common SNPs. We found that common SNPs explained certain amount of heritability with significance for all nine cancer sites: gastric cancer (20.26%), esophageal squamous cell carcinoma (19.86%), colorectal cancer (16.30%), lung cancer (LC) (15.17%), and epithelial ovarian cancer (13.31%), and a similar heritability around 10% for hepatitis B virus-related hepatocellular carcinoma, prostate cancer, breast cancer and nasopharyngeal carcinoma. We found that nearly or less than 25% change was shown when removing the regions expanding 250 kb or 500 kb upward and downward of the GWAS-reported SNPs. We also found strong linear correlations between variance partitioned by each chromosome and chromosomal length only for LC (R2  = 0.641, p = 0.001) and esophageal squamous cell cancer (R2  = 0.633, p = 0.002), which implied us the complex heterogeneity of cancers. These results indicate polygenic genetic architecture of the nine common cancers in Chinese population. Further efforts should be made to discover the hidden heritability of different cancer types among Chinese.

Risk of cancer in Asian Americans: a Kaiser Permanente cohort study

PURPOSE

To supplement published cohort data about incident cancer in Asian Americans (Asians) including risk of specific Asian ethnic groups.

METHODS

A cohort study in 124,193 persons (13,344 Asians) with baseline examination data in 1978-1985 used Cox proportional hazards models with seven covariates to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs).

RESULTS

Through 2012 cancer was diagnosed in 18,687 persons including 1,522 Asians. Compared to Whites, the HR (CIs) for any cancer in Asians was 0.8 (0.7-0.9, p < 0.001). Lower Asian risk was stronger for men (HR = 0.7, p < 0.001) than for women (HR = 0.9, p = 0.003). Lower Asian vs. White risks with p < 0.05 were found for cancers of the upper airway digestive area, hematologic malignancies, melanoma, and cancers of the prostate, bladder, and brain. Melanoma contributed substantially to lower Asian risk, especially in women. HRs for specific Asian groups versus Whites follow: Chinese = 0.9 (p < 0.001), Japanese = 0.9 (p = 0.01), Filipinos = 0.8 (p < 0.001), South Asians = 0.5 (p < 0.001), and Other Asians = 0.7 (p = 0.006). Both South Asian men and women had lower risk than Whites, and South Asians had lower risk than any other racial/ethnic group.

CONCLUSIONS

Asians had lower cancer risk than Whites, due to lower risk of several cancer types. Each Asian ethnic group had lower risk than Whites with South Asians at the lowest risk.

Ethnicity and the prostate cancer experience: a qualitative metasynthesis

Objectives

To summarize black and minority ethnic (BME) patients' and partners experiences of prostate cancer by examining the findings of existing qualitative studies.

Methods

We undertook a systematic metasynthesis of qualitative studies using a modified version of Noblit and Hare's “meta‐ethnography” approach, with a 2000‐2015 search of 7 databases.

Results

Thirteen studies of men from US and UK BME groups were included. We explored constructs with BME‐specific features. Health care provider relationships, formation of a spiritual alliance with God (which enhanced the participants' feeling of empowerment and ability to cope with the cancer), and living on for others (generally to increase cancer awareness), often connected to spiritual regrowth, were the 3 constructs most commonly reported. A magnified effect from erectile dysfunction was also common. Initially, this affected men's disclosure to others about their cancer and their sexual problems, but eventually men responded by shifting their conceptualizations of masculinity to sustain self and social identities. There was also evidence of inequality resulting from financial constraints and adversity that necessitated resilience in coping.

Conclusions

The prostate cancer experience of BME men and their partners is affected by a complex intersection of ethnicity with other factors. Health care services should acknowledge this. If providers recognize the men's felt masculinities, social identities, and spiritual beliefs and their shifting nature, services could be improved, with community as well as individual benefits. More studies are needed in diverse ethnic groups.

Putative effectors for prognosis in lung adenocarcinoma are ethnic and gender specific

Lung adenocarcinoma possesses distinct patterns of EGFR/KRAS mutations between East Asian and Western, male and female patients. However, beyond the well-known EGFR/KRAS distinction, gender and ethnic specific molecular aberrations and their effects on prognosis remain largely unexplored. Association modules capture the dependency of an effector molecular aberration and target gene expressions. We established association modules from the copy number variation (CNV), DNA methylation and mRNA expression data of a Taiwanese female cohort. The inferred modules were validated in four external datasets of East Asian and Caucasian patients by examining the coherence of the target gene expressions and their associations with prognostic outcomes. Modules 1 (cis-acting effects with chromosome 7 CNV) and 3 (DNA methylations of UBIAD1 and VAV1) possessed significantly negative associations with survival times among two East Asian patient cohorts. Module 2 (cis-acting effects with chromosome 18 CNV) possessed significantly negative associations with survival times among the East Asian female subpopulation alone. By examining the genomic locations and functions of the target genes, we identified several putative effectors of the two cis-acting CNV modules: RAC1, EGFR, CDK5 and RALBP1. Furthermore, module 3 targets were enriched with genes involved in cell proliferation and division and hence were consistent with the negative associations with survival times. We demonstrated that association modules in lung adenocarcinoma with significant links of prognostic outcomes were ethnic and/or gender specific. This discovery has profound implications in diagnosis and treatment of lung adenocarcinoma and echoes the fundamental principles of the personalized medicine paradigm.

Benign Prostatic Hyperplasia and the Risk of Prostate Cancer and Bladder Cancer: A Meta-Analysis of Observational Studies

Benign prostatic hyperplasia (BPH) has been suggested to be a risk factor for certain urologic cancers, but the current evidence is inconsistent.The aim of this study was to investigate the association between BPH and urologic cancers.MEDLINE, EMBASE, Cochrane Library, and Web of Science were searched for potential eligible studies.We included case-control studies or cohort studies, which evaluated the association between BPH and urologic cancers (including prostate cancer, bladder cancer, kidney cancer, testicular cancer, or penile cancer).Overall effect estimates were calculated using the DerSimonian-Laird method for a random-effects model. Summary effect-size was calculated as risk ratio (RR), together with the 95% confidence interval (CI).This systematic review included 16 case-control studies and 10 cohort studies evaluating the association of BPH and prostate or bladder cancer; we did not identify any study about other urologic cancers. Meta-analyses demonstrated that BPH was associated with an increased incidence of prostate cancer (case-control study: RR = 3.93, 95% CI = 2.18-7.08; cohort-study: RR = 1.41, 95% CI = 1.00-1.99) and bladder cancer (case-control study: RR = 2.50, 95% CI = 1.63-3.84; cohort-study: RR = 1.58, 95% CI = 1.28-1.95). Subgroup analysis by ethnicity suggested that the association between BPH and prostate cancer was much stronger in Asians (RR = 6.09, 95% CI = 2.96-12.54) than in Caucasians (RR = 1.54, 95% CI = 1.19-2.01). Egger's tests indicated low risk of publication bias (prostate cancer: P = 0.11; bladder cancer: P = 0.95).BPH is associated with an increased risk of prostate cancer and bladder cancer. The risk of prostate cancer is particularly high in Asian BPH patients. Given the limitations of included studies, additional prospective studies with strict design are needed to confirm our findings.

Molecular aspects of prostate cancer with neuroendocrine differentiation

Neuroendocrine differentiation (NED), which is not uncommon in prostate cancer, is increases in prostate cancer after androgen-deprivation therapy (ADT) and generally appears in castration-resistant prostate cancer (CRPC). Neuroendocrine cells, which are found in normal prostate tissue, are a small subset of cells and have unique function in regulating the growth of prostate cells. Prostate cancer with NED includes different types of tumor, including focal NED, pure neuroendocrine tumor or mixed neuroendocrine-adenocarcinoma. Although more and more studies are carried out on NED in prostate cancer, the molecular components that are involved in NED are still poorly elucidated. We review neuroendocrine cells in normal prostate tissue, NED in prostate cancer, terminology of NED and biomarkers used for detecting NED in routine pathological practice. Some recently reported molecular components which drive NED in prostate cancer are listed in the review.

Genistein increases estrogen receptor beta expression in prostate cancer via reducing its promoter methylation

Genistein has protective effects against prostate cancer (PCa) but whether this protection involves an estrogen receptor (ER) β dependent mechanism has yet to be elucidated. ER-β has a tumor suppressor role in PCa and its levels decline with cancer progression which was linked to ER-β promoter hypermethylation. Genistein has been suggested to have demethylating activities in cancer. However, the ability of genistein to reverse ER-β promoter hypermethylation in PCa has not been studied. In addition, there are great discrepancies among studies that examined the effect of genistein on ER-β gene expression. Therefore, we sought to explore effects of genistein on ER-β promoter methylation as a mechanism of modulating ER-β expression using three PCa cell lines, LNCaP, LAPC-4 and PC-3. We also examined the role of ER-β in mediating the preventive action of genistein. Our data demonstrated that genistein at physiological ranges (0.5-10 μmol/L) reduced ER-β promoter methylation significantly with corresponding dose-dependent increases in ER-β expression in LNCaP and LAPC-4 but not in PC-3 cells, which could be attributed to the low basal levels of ER-β promoter methylation in PC-3 cell line. Genistein induced phosphorylation, nuclear translocation and transcriptional activity of ER-β in all three PCa cell lines. Inhibitory effects of genistein on LAPC-4 and PC-3 cell proliferation were diminished using a specific ER-β antagonist. In conclusion, genistein and ER-β act together to prevent PCa cell proliferation; genistein increases ER-β levels via reducing its promoter methylation and ER-β, in turn, mediates the preventive action of genistein.

Prostate cancer in Asia: A collaborative report

The incidence of prostate cancer (PCa) within Asian population used to be much lower than in the Western population; however, in recent years the incidence and mortality rate of PCa in some Asian countries have grown rapidly. This collaborative report summarized the latest epidemiology information, risk factors, and racial differences in PCa diagnosis, current status and new trends in surgery management and novel agents for castration-resistant prostate cancer. We believe such information would be helpful in clinical decision making for urologists and oncologists, health-care ministries and medical researchers.

Cancer-specific mortality of Asian Americans diagnosed with cancer: a nationwide population-based assessment

BACKGROUND

Racial disparities in cancer survival outcomes have been primarily attributed to underlying biologic mechanisms and the quality of cancer care received. Because prior literature shows little difference exists in the socioeconomic status of non-Hispanic whites and Asian Americans, any difference in cancer survival is less likely to be attributable to inequalities of care. We sought to examine differences in cancer-specific survival between whites and Asian Americans.

METHODS

The Surveillance, Epidemiology, and End Results Program was used to identify patients with lung (n = 130 852 [16.9%]), breast (n = 313 977 [40.4%]), prostate (n = 166 529 [21.4%]), or colorectal (n = 165 140 [21.3%]) cancer (the three leading causes of cancer-related mortality within each sex) diagnosed between 1991 and 2007. Fine and Gray's competing risks regression compared the cancer-specific mortality (CSM) of eight Asian American groups (Chinese, Filipino, Hawaiian/Pacific Islander, Japanese, Korean, other Asian, South Asian [Indian/Pakistani], and Vietnamese) to non-Hispanic white patients. All P values were two-sided.

RESULTS

In competing risks regression, the receipt of definitive treatment was an independent predictor of CSM (hazard ratio [HR] = 0.37, 95% confidence interval [CI] = 0.35 to 0.40; HR = 0.55, 95% CI = 0.53 to 0.58; HR = 0.61, 95% CI = 0.60 to 0.62; and HR = 0.27, 95% CI = 0.25 to 0.29) for prostate, breast, lung, and colorectal cancers respectively, all P < .001). In adjusted analyses, most Asian subgroups (except Hawaiians and Koreans) had lower CSM relative to white patients, with hazard ratios ranging from 0.54 (95% CI = 0.38 to 0.78) to 0.88 (95% CI = 0.84 to 0.93) for Japanese patients with prostate and Chinese patients with lung cancer, respectively.

CONCLUSIONS

Despite adjustment for potential confounders, including the receipt of definitive treatment and tumor characteristics, most Asian subgroups had better CSM than non-Hispanic white patients. These findings suggest that underlying genetic/biological differences, along with potential cultural variations, may impact survival in Asian American cancer patients.

Fiber intake and risk of subsequent prostate cancer in Japanese men

BACKGROUND

Dietary fiber may reduce the risk of prostate cancer, possibly by increasing circulating concentrations of sex hormone-binding globulin and improving insulin sensitivity. However, results from previous epidemiologic studies of fiber intake and prostate cancer are inconsistent, and to our knowledge, no study has comprehensively evaluated the effects of soluble and insoluble fiber on prostate cancer in Asia.

OBJECTIVE

The objective was to examine the association between fiber intake and prostate cancer in Japanese men.

DESIGN

We conducted a population-based prospective study in 43,435 Japanese men aged 45-74 y. Participants responded to a validated questionnaire, which included 138 food items. Follow-up was from 1995 through 2009. HRs and 95% CIs of incidence were calculated according to quartiles of fiber intake.

RESULTS

During the 11.6-y follow-up, of the 825 men newly diagnosed with prostate cancer, 213 had advanced-stage cancer, 582 had organ-localized disease, and 30 had an undetermined stage of disease. Among them, 217 cases were detected by subjective symptoms. Total fiber was not associated with total or advanced prostate cancer, with respective multivariable HRs for the highest and lowest quartiles of 1.00 (95% CI: 0.77, 1.29; P-trend = 0.97) and 0.67 (95% CI: 0.42, 1.07; P-trend = 0.30). Total fiber and insoluble fiber intake were associated with a decreased risk of advanced cancers detected by subjective symptoms, with multivariate HRs (95% CIs) across increasing quartiles of 1.00, 0.58, 0.62, and 0.44 (0.21, 0.92; P-trend = 0.05) for total fiber and 1.00, 0.60, 0.52, and 0.46 (0.22, 0.93; P-trend = 0.04) for insoluble fiber. Soluble fiber intake showed no association with prostate cancer.

CONCLUSIONS

Dietary fiber is inversely associated with advanced prostate cancer detected by subjective symptoms even among populations with relatively low intake, such as Japanese. These results suggest that a very low intake of dietary fiber is associated with an increased risk of prostate cancer.

Serum chromogranin A is a useful marker for Japanese patients with pancreatic neuroendocrine tumors

Although chromogranin A (CGA) is a useful marker for pancreatic neuroendocrine tumors (pNET) in the West, its usefulness in Japanese populations is unclear. To assess this, we evaluated the serum CGA levels in 189 patients with various pancreatic diseases, including proven pNET (n = 69), pancreatic cancer (PC) (n = 50), chronic pancreatitis (CP) (n = 50) and autoimmune pancreatitis (AIP) (n = 20), and 112 normal controls (controls) using an ELISA kit. The mean CGA level of patients with pNET was significantly higher than any of the other groups (407.8 ± 984.6 ng/mL [pNET] vs 91.8 ± 101.8 ng/mL [PC], 93.6 ± 57.5 ng/mL [CP], 69.9 ± 52.4 ng/mL [AIP] and 62.5 ± 48.3 ng/mL [controls]). Limiting the analysis to patients not using proton pump inhibitors (PPI), the CGA level of patients with PC or CP was not significantly different compared with the controls. Discriminant analysis revealed that the best cut-off value of CGA to distinguish patients with pNET from the controls was 78.7 ng/mL, with a sensitivity and specificity of 53.6% and 78.6%, respectively. In patients with pNET, significant factors associating with elevated CGA levels were tumor classification, tumor size, and the presence of liver metastases in univariate analysis as well as PPI use and the presence of liver metastases in multivariate analysis. We show that CGA is a useful marker for diagnosing pNET in Japanese populations and for distinguishing patients with pNET from patients with other pancreatic diseases. The increased use of CGA in Japan will likely be a helpful tool in managing these patients, as found in the West.

Impact of soy isoflavones on the epigenome in cancer prevention

Isoflavones (IF) such as genistein are cancer preventive phytochemicals found in soy and other legumes. Epidemiological studies point to a reduced risk for hormone‑dependent cancers in populations following a typical Asian diet rich in soy products. IF act as phytoestrogens and prevent tumorigenesis in rodent models by a broad spectrum of bioactivities. During the past 10 years, IF were shown to target all major epigenetic mechanisms regulating gene expression, including DNA methylation, histone modifications controlling chromatin accessibility, and non-coding RNAs. These effects have been suggested to contribute to cancer preventive potential in in vitro and in vivo studies, affecting several key processes such as DNA repair, cell signaling cascades including Wnt-signaling, induction of apoptosis, cell cycle progression, cell proliferation, migration and invasion, epithelial-mesenchymal transition (EMT), metastasis formation and development of drug-resistance. We here summarize the state-of-the-art of IF affecting the epigenome in major hormone-dependent, urogenital, and gastrointestinal tumor types and in in vivo studies on anti-cancer treatment or developmental aspects, and short-term intervention studies in adults. These data, while often requiring replication, suggest that epigenetic gene regulation represents an important novel target of IF and should be taken into consideration when evaluating the cancer preventive potential of IF in humans.

A monocarbonyl analogue of curcumin, 1,5-bis(3-hydroxyphenyl)-1,4-pentadiene-3-one (Ca 37), exhibits potent growth suppressive activity and enhances the inhibitory effect of curcumin on human prostate cancer cells

Prostate carcinoma is one of the leading causes of cancer-related morbidity and mortality in males in western countries. Curcumin exhibits growth-suppressive activity against several cancers, including prostate cancer, but it has poor bioavailability. The purpose of this study was to evaluate the anticancer potency and mechanism of a curcumin analogue, 1,5-bis(3-hydroxyphenyl)-1,4-pentadiene-3-one (Ca 37), in human prostate cancer. Studies were performed in established human prostate cancer cell lines (PC-3 and DU145) as well as in a murine xenograft tumor (PC-3) model. Ca 37 presented a preferential suppression capacity against growth and migration toward prostate cancer cells compared with curcumin. Ca 37 impaired the bioenergetics system, promoted cell cycle arrest and apoptosis activation in PC-3 cells. In addition, 0.5 μmol (6.65 mg/kg body weight) of Ca 37 significantly inhibited the growth of the prostate xenografted tumors, whereas 6 μmol (110 mg/kg body weight) of curcumin had little effect. Furthermore, a combination of Ca 37 and curcumin resulted in enhanced antitumor activity in prostate cancer cells. N-Acetylcysteine abrogated both reactive oxygen species (ROS) production and viability loss induced by Ca 37 but partially prevented growth inhibition in PC-3 cells treated with curcumin alone, or a combination with Ca 37. The data indicate that induction of ROS plays a vital role in the growth inhibitory effect of Ca 37 in PC-3 cells. This study suggests that Ca 37, alone or in combination with curcumin, may be a promising anticancer agent for prostate cancer therapy.

Soy isoflavones and prostate cancer: a review of molecular mechanisms

Soy isoflavones are dietary components for which an association has been demonstrated with reduced risk of prostate cancer (PCa) in Asian populations. However, the exact mechanism by which these isoflavones may prevent the development or progression of PCa is not completely understood. There are a growing number of animal and in vitro studies that have attempted to elucidate these mechanisms. The predominant and most biologically active isoflavones in soy products, genistein, daidzein, equol, and glycetin, inhibit prostate carcinogenesis in some animal models. Cell-based studies show that soy isoflavones regulate genes that control cell cycle and apoptosis. In this review, we discuss the literature relevant to the molecular events that may account for the benefit of soy isoflavones in PCa prevention or treatment. These reports show that although soy isoflavone-induced growth arrest and apoptosis of PCa cells are plausible mechanisms, other chemo protective mechanisms are also worthy of consideration. These possible mechanisms include antioxidant defense, DNA repair, inhibition of angiogenesis and metastasis, potentiation of radio- and chemotherapeutic agents, and antagonism of estrogen- and androgen-mediated signaling pathways. Moreover, other cells in the cancer milieu, such as the fibroblastic stromal cells, endothelial cells, and immune cells, may be targeted by soy isoflavones, which may contribute to soy-mediated prostate cancer prevention. In this review, these mechanisms are discussed along with considerations about the doses and the preclinical models that have been used.

Alcohol and smoking and subsequent risk of prostate cancer in Japanese men: the Japan Public Health Center-based prospective study

Although alcohol and smoking have not been established as risk factors for prostate cancer, they are important risk factors for other human cancers and potentially major avoidable factors. Alcohol drinkers and smokers might be less likely to get screening, which might lead to attenuation of the positive association. Here, we investigated the association of alcohol drinking and smoking and prostate cancer according to stage, as well as prostate cancer detected by subjective symptoms, in a large prospective study among Japanese men. The Japan Public Health Center-based prospective study (JPHC study) was established in 1990 for Cohort I and in 1993 for Cohort II. Subjects were 48,218 men aged 40-69 years who completed a questionnaire, which included their alcohol and smoking habits at baseline, and who were followed until the end of 2010. During 16 years of follow-up, 913 men were newly diagnosed with prostate cancer; of whom 248 had advanced cases, 635 were organ-localized and 30 were of an undetermined stage. Alcohol consumption was dose-dependently associated with advanced prostate cancer [nondrinkers: reference, 0-150 g/week: hazard ratio (HR) = 1.23, 95% confidence interval (CI) = 0.83-1.82; 150-300 g/week: HR = 1.51, 95% CI = 1.04-2.19; ≥ 300 g/week: HR = 1.41, 95% CI = 0.97-2.05, p for trend = 0.02]. The positive association was not substantially changed among cancers detected by subjective symptoms. Smoking was inversely associated with prostate cancer among total subjects, but tended to increase the risk of advanced prostate cancer detected by subjective symptoms. In conclusion, abstinence from alcohol and prohibition of smoking might be important factors in the prevention of advanced prostate cancer.

The molecular basis for ethnic variation and histological subtype differences in prostate cancer

Prostate cancer is a common malignancy among men in Western countries. Recently the morbidity and mortality of prostate cancer increase dramatically in several oriental countries including China. Rapidly evolving technology in molecular biology such as high-throughput sequencing and integrative analysis of genomic and transcriptomic landscapes have enabled the identification of key oncogenic events for prostate cancer initiation, progression and resistance to hormonal therapy. These surging data of prostate cancer genome also provide insights on ethnic variation and the differences in histological subtype of this disease. In this review, differences in the incidence of prostate cancer and the prevalence of main genetic alterations between Asian and Western populations are discussed. We also review the recent findings on the mechanisms underlying neuroendocrine differentiation of prostate cancer and the development of small cell neuroendocrine carcinoma after androgen deprivation therapy.