Early management of prostate cancer: how to respond to an elevated PSA?

Point-of-Care Prostate Specific Antigen Testing: Examining Translational Progress toward Clinical Implementation

Prostate cancer (PCa) is the second most common male cancer and is attributable to over 375,000 deaths annually. Prostate specific antigen (PSA) is a key biomarker for PCa and therefore measuring patient PSA levels is an important aspect of the diagnostic pathway. Automated immunoassays are currently utilized for PSA analysis, but they require a laboratory setting with specialized equipment and trained personnel. This results in high diagnostic costs, extended therapeutic turnaround times, and restrictions on testing capabilities in resource-limited settings. Consequently, there is a strong drive to develop point-of-care (PoC) PSA tests that can offer accurate, low-cost, and rapid results at the time and place of the patient. However, many emerging PoC tests experience a trade-off between accuracy, affordability, and accessibility which distinctly limits their translational potential. This review comprehensively assesses the translational advantages and limitations of emerging laboratory-level and commercial PoC tests for PSA determination. Electrochemical and optical PSA sensors from 2013 to 2023 are systematically examined. Furthermore, we suggest how the translational potential of emerging tests can be optimized to achieve clinical implementation and thus improve PCa diagnosis globally.

Gene-environment interactions in case-control studies with silent disease

Genome-wide association studies (GWAS) often measure gene-environment interactions (G × E). We consider the problem of accurately estimating a G × E in a case-control GWAS when a subset of the controls have silent, or undiagnosed, disease and the frequency of the silent disease varies by the environmental variable. We show that using case-control status without accounting for misdiagnosis can lead to biased estimates of the G × E. We further propose a pseudolikelihood approach to remove the bias and accurately estimate how the relationship between the genetic variant and the true disease status varies by the environmental variable. We demonstrate our method in extensive simulations and apply our method to a GWAS of prostate cancer.

Circulating microRNAs: potential biomarkers for common malignancies

MicroRNAs (miRNAs) belong to a class of small noncoding RNAs (ncRNAs), which regulate gene expression at the post-transcriptional level. They are approximately 22 nucleotide sequences in length and have been predicted to control expression of up to 30-60% of all protein-coding genes in mammals. Considering this wide involvement in gene control, aberrant miRNA expression has a strong association with the presence and progression of a disease, hence generating much anticipation in using miRNAs as biomarkers for the diagnosis and prognosis of human cancers. The majority of these miRNAs are intracellular, but recently they have been discovered in bodily fluids. This review will provide an insight into these circulatory miRNA molecules and discuss their potential as cancer biomarkers.

Electrophoretic fingerprint metallothionein analysis as a potential prostate cancer biomarker

Prostate-specific antigen (PSA) is a routinely used marker of prostate cancer; however, the cut-off values for unambiguous positive/negative prostate cancer diagnoses are not defined. Therefore, despite the best effort, certain percentage of misdiagnosed cases is being recorded every year. For this reason, search for more specific diagnostic markers is of great interest. In this study, systematic comparison of PSA and metallothionein (MT) levels in blood serum of 46 prostate cancer-diagnosed patients is presented. It is clearly demonstrated that PSA levels vary significantly and despite normal total PSA values in the range of 0 - 4 ng/mL were obtained in over 36.9% of cases, positive prostate cancer was diagnosed by biopsy. In contrary, MT levels were considerably elevated in all tested samples and no significant variations were observed. These results are indicating the potential of MT as an additional prostate cancer marker reducing, in combination with PSA, the probability of false positive/negative diagnosis. To increase the throughput of the screening, chip-based capillary electrophoresis was suggested as a rapid and effective method for the fingerprinting analysis of prostate cancer from diseased blood sera.

Early Prostate Cancer Antigen Expression in Predicting Presence of Prostate Cancer in Men With Histologically Negative Biopsies

PURPOSE

Early prostate cancer antigen is a nuclear matrix protein that was recently shown to be expressed in prostate adenocarcinoma and adjacent benign tissue. Previous studies have demonstrated early prostate cancer antigen expression in benign prostate tissue up to 5 years before a diagnosis of prostate carcinoma, suggesting that early prostate cancer antigen could be used as a potential predictive marker.

MATERIALS AND METHODS

We evaluated early prostate cancer antigen expression by immunohistochemistry using a polyclonal antibody (Onconome Inc., Seattle, Washington) on benign biopsies from 98 patients. Biopsies were obtained from 4 groups that included 39 patients with first time negative biopsy (group 1), 24 patients with persistently negative biopsies (group 2), 8 patients with initially negative biopsies who were subsequently diagnosed with prostate carcinoma (group 3) and negative biopsies obtained from 27 cases where other concurrent biopsies contained prostate carcinoma (group 4). Early prostate cancer antigen staining was assessed by 2 of the authors who were blind to the group of the examined sections. Staining intensity (range 0 to 3) and extent (range 1 to 3) scores were assigned. The presence of intensity 3 staining in any of the blocks of a biopsy specimen was considered as positive for early prostate cancer antigen for the primary outcome in the statistical analysis. In addition, as secondary outcomes we evaluated the data using the proportion of blocks with intensity 3 early prostate cancer antigen staining, the mean of the product of staining intensity and staining extent of all blocks within a biopsy, and the mean of the product of intensity 3 staining and extent.

RESULTS

Primary outcome analysis revealed the proportion of early prostate cancer antigen positivity to be highest in group 3 (6 of 8, 75%) and lowest in group 2 (7 of 24, 29%, p=0.04 for differences among groups). A relatively higher than expected proportion of early prostate cancer antigen positivity was present in group 1 (23 of 39, 59%). Early prostate cancer antigen was negative in 41% of group 4 who were known to harbor prostate carcinoma. The proportion of early prostate cancer antigen positivity was statistically significantly lower in group 2 than in each of the other groups when compared pairwise. A lower proportion of early prostate cancer antigen positivity was encountered in older archival tissue blocks (p<0.0001) pointing to a potential confounding factor. Corrected for block age, group 3 was the only group to remain statistically significantly different in early prostate cancer antigen positivity compared to the reference group 2. Similar findings were obtained when adjustments for patient age were made and when analysis was based on secondary outcome measurements.

CONCLUSIONS

Our study showed a higher proportion of early prostate cancer antigen expression in initial negative prostate biopsy of patients who were diagnosed with prostate carcinoma on subsequent followup biopsies. We found a relatively high proportion of early prostate cancer antigen positivity (59%) in the group with first time negative biopsies and a potential 41% rate of false-negative early prostate cancer antigen staining in benign biopsies from cases with documented prostate carcinoma on concurrent cores. The lower early prostate cancer antigen positivity in cases with older blocks raises the question of a confounding effect of block age. Additional studies on the antigenic properties of early prostate cancer antigen in archival material are required to further delineate the usefulness of early prostate cancer antigen immunostaining on biopsy material.

The clinical use of tumor makers in select cancers: are you confident enough to discuss them with your patients?

PURPOSE/OBJECTIVES

To review the clinical use of tumor markers in select cancers and highlight future directions in tumor marker development.

DATA SOURCES

Guidelines from national and international societies, scientific literature, and Internet resources.

DATA SYNTHESIS

Tumor markers are important tools in the management of cancer. Sequencing of the human genome has led to new tumor marker development in the fields of proteomics and DNA microarray technologies.

CONCLUSIONS

Tumor marker technology is expanding rapidly; almost a dozen tumor markers currently are being used in the oncology arena, with many more in development. The use of tumor markers can be controversial, particularly because guidelines have not been established for all of the markers.

IMPLICATIONS FOR NURSING

Oncology nurses need to be well versed in the use of tumor markers to educate and counsel patients with cancer.

¿Cuál es el algoritmo diagnóstico más apropiado para el cribado del cáncer de próstata?

Since the use of PSA to detect prostate cancer was generalised in the late 1980's, prostate cancer diagnosis has increased considerably. Although there is now indirect evidence pointing to the beneficial effect of screening, there are no data justifying PSA screening in the general population. There is also a controversy concerning the most appropriate algorithm, should screening be performed. Therefore, our aim was to review the literature and, based on our experience, attempt to define the best algorithm for prostate cancer screening. We have made a search on Medline using the following terms: prostate biopsy, screening, algorithms, radical prostatectomy, PSA and prostate cancer. After analysing the literature, we can confirm that there is no "definitive" algorithm, due to the rapid appearance and use of new technical and biological breakthroughs, although it appears that at this time, without ceasing to include a rectal examination, more value should be given to personal risk factors, including PSA, at ages under 50, with individual monitoring based on these factors. The algorithms applied to a population have first to be validated for the population concerned.

Effects of False-Positive Prostate Cancer Screening Results on Subsequent Prostate Cancer Screening Behavior

Objectives: Little is known about screening behavior following a false-positive prostate cancer screening result, which we have defined as a screening result with “abnormal/suspicious” labeling that did not result in a prostate cancer diagnosis within 14 months. The purpose of this analysis was to examine whether age, race, education, or previous false-positive prostate cancer screening results via prostate-specific antigen or digital rectal exam predict decision to obtain subsequent prostate cancer screening.

Methods: Data were drawn from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. The study sample consisted of 2,290 older men (mean age, 62.8 years; range, 55-75 years) who had false-positive (n = 318) or negative (n = 1,972) prostate-specific antigen or digital rectal exam baseline prostate cancer screening results. Multivariable logistic regression was used to assess the effect of false-positive results on subsequent prostate cancer screening behavior, adjusting for all covariates.

Results: The multivariable model showed that being African American (P = 0.016), and having a high school education or less (P = 0.007), having a previous false-positive prostate cancer screening result (P &lt; 0.001), were predictive of not returning for prostate cancer screening in the following screening trial year.

Conclusion: The study results highlight the importance of shared decision making between patients and their providers regarding the risks and benefits of prostate cancer screening, and follow-up options for abnormal prostate cancer screening results. Shared decision making may be especially important for African American men, whom prostate cancer disproportionately affects.

Cost-effectiveness analysis of bicalutamide (Casodex) for adjuvant treatment of early prostate cancer

OBJECTIVES

To assess the cost-effectiveness of bicalutamide (Casodex) as adjuvant treatment in early prostate cancer (EPC).

METHODS

A Markov state transition model was developed, using disease progression rates from a large (N = 8113) clinical trial program comparing bicalutamide in addition to standard care with standard care alone. Utility scores for different disease stages were obtained from published reports. Costs of disease progression were obtained from a retrospective patient chart analysis in six Belgian centers (n = 60). The time horizon was 15 years and the analysis was conducted from the public payer perspective.

RESULTS

The model showed good validity in predicting clinical outcomes. At a time horizon of 15 years, an incremental cost-effectiveness of 27,059 euros/QALY was obtained. The main factors influencing conclusions included the time horizon, the duration of bicalutamide treatment, which was set at a maximum (5 years) in the base case, and possible differences in prognosis of metastatic cancer between comparators. Also the discounting of health effects significantly altered cost-effectiveness ratios. Many of these influences are inherently associated with any cost-effectiveness analysis related to treatment of early, slowly progressing malignancies because such an analysis requires a sufficient time horizon to include not only the treatment costs but its benefits as well.

CONCLUSION

Based on the current data, bicalutamide appears to be a cost-effective option for adjuvant treatment of EPC.