The implementation of screening for prostate cancer

Prognostic microRNAs as biomarkers for prostate cancer

OBJECTIVE

Prostate cancer is the second largest cancer, most commonly diagnosed in men. Several studies reveal that miRNAs (microRNAs) are involved in various stages of prostate cancer. miRNAs are a family of small non-coding RNA species that have been implicated in the post-transcriptional regulation of gene expression. The present in silico study aims at identifying miRNA biomarkers that are significantly associated with the regulation of genes involved in prostate cancer.

METHODS

Dataset of miRNA and mRNA of prostate adenocarcinoma patients and controls was downloaded from The Cancer Genome Atlas (TCGA), and differential gene expression analysis was carried out. ROC and Kaplan-Meier survival analyses were performed on differentially expressed miRNAs. Pathway analysis was carried out for significant miRNAs, and protein-protein interaction of involved genes and miRNAs was examined.

RESULTS

A total of 185 miRNAs were differentially expressed between the patients and the control. ROC and Kaplan-Meier survival analysis showed that the two miRNAs hsa-mir-133b and hsa-mir-17-5p were found to be significantly associated with prostate cancer prognosis. HAS2 and EPHA10 gene targets of identified miRNA were also differentially expressed. A protein-protein interaction (PPI) network was constructed, and the HAS2 gene was found to be interacting with the epidermal growth factor receptor (EGFR).

CONCLUSION

This study highlights the potential of hsa-mir-133b and hsa-mir-17-5p miRNAs as biomarkers for the prognosis of prostate cancer. However, further experimental studies are required to validate this finding.

Prostate cancer screening: Continued controversies and novel biomarker advancements

Prostate cancer (PCa) screening remains one of the most controversial topics in clinical and public health. Despite being the second most common cancer in men worldwide, recommendations for screening using prostate-specific antigen (PSA) are unclear. Early detection and the resulting postscreening treatment lead to overdiagnosis and overtreatment of otherwise indolent cases. In addition, several unwanted harms are associated with PCa screening process. This literature review focuses on the limitations of PSA-specific PCa screening, reasons behind the screening controversy, and the novel biomarkers and advanced innovative methodologies that improve the limitations of traditional screening using PSA. With the verdict of whether or not to screen not yet unanimous, we hope to aid in resolution of the long-standing debate.

Cancer Incidence and Mortality Rates in Multiple Sclerosis: A Matched Cohort Study

OBJECTIVE

To determine whether cancer risk differs in people with and without multiple sclerosis (MS), we compared incidence rates and cancer-specific mortality rates in MS and matched cohorts using population-based data sources.

METHODS

We conducted a retrospective matched cohort study using population-based administrative data from Manitoba and Ontario, Canada. We applied a validated case definition to identify MS cases, then selected 5 controls without MS matched on birth year, sex, and region. We linked these cohorts to cancer registries, and estimated incidence of breast, colorectal, and 13 other cancers. For breast and colorectal cancers, we constructed Cox models adjusting for age at the index date, area-level socioeconomic status, region, birth cohort year, and comorbidity. We pooled findings across provinces using meta-analysis.

RESULTS

We included 53,983 MS cases and 269,915 controls. Multivariable analyses showed no difference in breast cancer risk (pooled hazard ratio [HR] 0.92 [95% confidence interval (CI) 0.78-1.09]) or colorectal cancer risk (pooled HR 0.83 [95% CI 0.64-1.07]) between the cohorts. Mortality rates for breast and colorectal did not differ between cohorts. Bladder cancer incidence and mortality rates were higher among the MS cohort. Although the incidence of prostate, uterine, and CNS cancers differed between the MS and matched cohorts, mortality rates did not.

CONCLUSION

The incidence of breast and colorectal cancers does not differ between persons with and without MS; however, the incidence of bladder cancer is increased. Reported differences in the incidence of some cancers in the MS population may reflect ascertainment differences rather than true differences.

Circulating miRNAs as Biomarkers for Prostate Cancer Diagnosis in Subjects with Benign Prostatic Hyperplasia

Body fluids often contain freely circulating nucleic acids, many of which can be exploited as noninvasive tools for the diagnosis of cancer as well as for clinical prognostication. Identifying microRNAs (miRNAs) in subjects' blood with various malignancies means that they can serve as novel biomarkers for prostate cancer (PCa) diagnosis. This study analyzed serum-circulating miRNAs as a noninvasive biomarker in subjects with PCa and subjects with benign prostatic hyperplasia (BPH). In total, 31 PCa subjects and 31 BPH subjects were included, with the BPH group serving as the control group. RT-qPCR was used to quantify the levels of 10 miRNAs, which included miR-18a, miR-34a, miR-106b, miR-183, miR-200a, miR-301a, miR-141, miR-182, miR-200b, and miR-375 in serum. Statistical tests were used to assess the relationship between the levels of miRNAs and the clinicopathological data. A significant increase was observed in the relative expression ratios of miR-141, miR-182, miR-200b, and miR-375 (1.89-, 2.09-, 2.41-, and 2.27-folds, respectively) in the PCa group when compared to the BPH group. Based on the receiver operating characteristic (ROC) analysis, the largest area under the curve (AUC), 0.923, was associated with the miR-200b group, indicating effective diagnostic properties for this biomarker. A correlation was observed between total prostate-specific antigen (TPSA) and the relative levels of miR-141, miR-182, miR-200b, and miR-375. The Gleason score and the miR-200b expression level were also correlated. These results are consistent with previous studies regarding the possibility of differentiating between PCa subjects and healthy controls based on the detection of miRNA. The findings attest to a distinctive expression profile of miRNA that is detectable in the blood of PCa subjects, thereby confirming the role of miRNAs as diagnostic biomarkers for PCa.

A Circulating MicroRNA Signature as a Biomarker for Prostate Cancer in a High Risk Group

Introduction: Mi(cro)RNAs are small non-coding RNAs whose differential expression in tissue has been implicated in the development and progression of many malignancies, including prostate cancer. The discovery of miRNAs in the blood of patients with a variety of malignancies makes them an ideal, novel biomarker for prostate cancer diagnosis. The aim of this study was to identify a unique expression profile of circulating miRNAs in patients with prostate cancer attending a rapid access prostate assessment clinic. Methods: To conduct this study blood and tissue samples were collected from 102 patients (75 with biopsy confirmed cancer and 27 benign samples) following ethical approval and informed consent. These patients were attending a prostate assessment clinic. Samples were reverse-transcribed using stem-loop primers and expression levels of each of 12 candidate miRNAs were determined using real-time quantitative polymerase chain reaction. miRNA expression levels were then correlated with clinicopathological data and subsequently analysed using qBasePlus software and Minitab. Results: Circulating miRNAs were detected and quantified in all subjects. The analysis of miRNA mean expression levels revealed that four miRNAs were significantly dysregulated, including let-7a (p = 0.005) which has known tumour suppressor characteristics, along with miR-141 (p = 0.01) which has oncogenic characteristics. In 20 patients undergoing a radical retropubic-prostatectomy, the expression levels of miR-141 returned to normal at day 10 post-operatively. A panel of four miRNAs could be used in combination to detect prostate cancer with an area under the curve (AUC) of 0.783 and a PPV of 80%. Conclusion: These findings identify a unique expression profile of miRNA detectable in the blood of prostate cancer patients. This confirms their use as a novel, diagnostic biomarker for prostate cancer.

Ultrasensitive electrochemical immunoassay of proteins based on in situ duple amplification of gold nanoparticle biolabel signals

An electrochemical sandwich immunoassay method that can be sensitive to a few protein molecules (human immunoglobulin G or human prostate-specific antigen) is reported based on in situ duple amplification of gold nanoparticle biolabel signals.

Delayed radical prostatectomy for intermediate-risk prostate cancer is associated with biochemical recurrence: possible implications for active surveillance from the SEARCH database

INTRODUCTION

Active surveillance (AS) is increasingly accepted as appropriate management for low-risk prostate cancer (PC) patients. It is unknown whether delaying radical prostatectomy (RP) is associated with increased risk of biochemical recurrence (BCR) for men with intermediate-risk PC.

METHODS

We performed a retrospective analysis of 1,561 low and intermediate-risk men from the Shared Equal Access Regional Cancer Hospital (SEARCH) database treated with RP between 1988 and 2011. Patients were stratified by interval between diagnosis and RP (≤ 3, 3-6, 6-9, or >9 months) and by risk using the D'Amico classification. Cox proportional hazard models were used to analyze BCR. Logistic regression was used to analyze positive surgical margins (PSM), extracapsular extension (ECE), and pathologic upgrading.

RESULTS

Overall, 813 (52%) men were low-risk, and 748 (48%) intermediate-risk. Median follow-up among men without recurrence was 52.9 months, during which 437 men (38.9%) recurred. For low-risk men, RP delays were unrelated to BCR, ECE, PSM, or upgrading (all P > 0.05). For intermediate-risk men, however, delays >9 months were significantly related to BCR (HR: 2.10, P = 0.01) and PSM (OR: 4.08, P < 0.01). Delays >9 months were associated with BCR in subsets of intermediate-risk men with biopsy Gleason score ≤ 3 + 4 (HR: 2.51, P < 0.01), PSA ≤ 6 (HR: 2.82, P = 0.06), and low tumor volume (HR: 2.59, P = 0.06).

CONCLUSIONS

For low-risk men, delayed RP did not significantly affect outcome. For men with intermediate-risk disease, delays >9 months predicted greater BCR and PSM risk. If confirmed in future studies, this suggests delayed RP for intermediate-risk PC may compromise outcomes.

Risk stratification in prostate cancer screening

Screening for prostate cancer is a controversial topic within the field of urology. The US Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial did not demonstrate any difference in prostate-cancer-related mortality rates between men screened annually rather than on an 'opportunistic' basis. However, in the world's largest trial to date--the European Randomised Study of Screening for Prostate Cancer--screening every 2-4 years was associated with a 21% reduction in prostate-cancer-related mortality rate after 11 years. Citing the uncertain ratio between potential harm and potential benefit, the US Preventive Services Task Force recently recommended against serum PSA screening. Although this ratio has yet to be elucidated, PSA testing--and early tumour detection--is undoubtedly beneficial for some individuals. Instead of adopting a 'one size fits all' approach, physicians are likely to perform personalized risk assessment to minimize the risk of negative consequences, such as anxiety, unnecessary testing and biopsies, overdiagnosis, and overtreatment. The PSA test needs to be combined with other predictive factors or be used in a more thoughtful way to identify men at risk of symptomatic or life-threatening cancer, without overdiagnosing indolent disease. A risk-adapted approach is needed, whereby PSA testing is tailored to individual risk.

Pathological significance and predictive value for biochemical recurrence of c-Fes expression in prostate cancer

BACKGROUND

c-Fes is a proto-oncogene encoded non-receptor protein-tyrosine kinase (PTK). However, genetic studies have indicated that it has anti-tumorigenic effects in certain cancers. The pathological and clinical significance of c-Fes in prostate cancer are unknown.

METHODS

Expression of c-Fes was evaluated in normal glands, prostatic intraepithelial neoplasia (PIN), cancer cells in tissues of knock-in mouse adenocarcinoma prostate (KIMAP) model, and prostate cancer patients free of metastasis. Expression of c-Fes was analyzed by immunohistochemistry, and quantified by using the immunoreactivity score (IRS) (staining intensity × percentage of positive cells). Relationships between c-Fes expression and pT stage, Gleason's score (GS), and biochemical recurrence in patients who underwent radical surgery were also investigated.

RESULTS

In KIMAP, the percentage in normal glands, PIN and cancer cells positive for c-Fes expression were 0 (0/7), 25.0 (2/8), and 100% (7/7), respectively. In human tissues, c-Fes expression was also significantly higher in cancer cells than in normal cells and PIN, and it correlated with pT stage (P < 0.001) and GS (P = 0.047). Multivariate analysis showed that c-Fes expression was an independent predictor of poor outcome poor prognosis (hazard ratio = 3.21, 95% confidence interval = 1.11-9.37, P = 0.032).

CONCLUSION

The results suggested that c-Fes expression is a useful predictor of biochemical recurrence after radical surgery. The results also suggested that c-Fes is a potentially useful therapeutic target in prostate cancer and a predictor of biochemical recurrence after radical prostatectomy.

Predictive value of digital rectal examination for prostate cancer detection is modified by obesity

The American Cancer Society's updated screening guidelines for prostate cancer (CaP) render digital rectal examination (DRE) optional. We investigated the impact of DRE on CaP detection among obese men. Data from 2794 men undergoing initial prostate biopsy at three centers were analyzed to assess CaP risk attributed to abnormal DRE across body mass index (BMI) categories. Predictive accuracies of a combination of PSA, age, race, center and biopsy year including or excluding DRE findings were compared by areas under the receiver-operating characteristics curves. In all cohorts, obese men were less likely to have abnormal DREs diagnosed than non-obese men. As BMI category increased, abnormal DREs became stronger predictors for overall CaP in individual (P-trends ≤ 0.05) and combined (P-trend<0.001) cohorts, and for high-grade CaP in the Italian (P-trend=0.03) and combined (P-trend=0.03) cohorts. DRE inclusion improved the predictive accuracy for overall and high-grade CaP detection among all obese men (P ≤ 0.032) but not normal-weight men (P ≥ 0.198). DRE inclusion also near-significantly improved overall CaP detection in obese men with PSA<4 ng ml(-1) (P=0.081). In conclusion, the predictive value of DRE is dependent on obesity and is significantly higher among obese men than normal-weight men.

Microfluidic-based multiplex qRT-PCR identifies diagnostic and prognostic microRNA signatures in the sera of prostate cancer patients

Recent prostate-specific antigen-based screening trials indicate an urgent need for novel and noninvasive biomarker identification strategies to improve the prediction of prostate cancer behavior. Noncoding microRNAs (miRNA) in the serum and plasma have been shown to have potential as noninvasive markers for physiologic and pathologic conditions. To identify serum miRNAs that diagnose and correlate with the prognosis of prostate cancer, we developed a multiplex quantitative reverse transcription PCR method involving the purification of multiplex PCR products followed by uniplex analysis on a microfluidics chip to evaluate 384 human miRNAs. Using Dgcr8 and Dicer knockout (small RNA-deficient) mouse ES cells as the benchmark, we confirmed the validity of our technique and uncovered a considerable lack of accuracy in previously published methods. Profiling 48 sera from healthy men and untreated prostate cancer patients with differing CAPRA scores, we identified miRNA signatures that allow us to diagnose cancer patients and correlate with a prognosis. These serum signatures include oncogenic and tumor-suppressive miRNAs, suggesting functional roles in prostate cancer progression.