Prevention strategies in prostate cancer

Men's willingness to pay for prostate cancer screening: a systematic review

BACKGROUND

This study aimed to review studies on willingness to pay (WTP) for prostate cancer screening.

METHODS

This systematic-review was conducted based on the Preferred Reporting Items for Systematic Reviews guidelines. By searching six-health-database, WTP studies on prostate cancer screening using contingent valuation method published in English until March 2020 were included and those with unavailable full-text and inadequate quality-assessment scores were excluded. Smith checklist was used for the quality assessment. Extracted WTPs were converted to US dollar in 2018 using exchange rate parity and net present value formula to make comparison. Factors' effect was assessed by vote counting.

RESULTS

Six final studies published after 2006 reported above 70% Smith checklist items needed to be considered in contingent valuation study reports. Seven factors have positive effects on WTP. The reported WTP value varied from 11$ to 588$ in Japan and Germany, respectively.

CONCLUSION

WTP for prostate cancer screening was positive among all studied men. The results of factors' effect assessment showed that better understanding prostate cancer risks or screening tests and factors such as age, income, family history of cancer, hospitalization history, and educational level have positive effects. Moreover, prostate-specific antigen history, health insurance, employment, and subject's health assessment received less attention. The results' generalization to all countries is not applicable because there are no studies for low- and middle-income countries.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2020 CRD42020172789.

Metformin therapy and prostate cancer risk: a meta-analysis of observational studies

OBJECTIVE

Several observational studies have shown that metformin therapy may modify the risk of prostate cancer. We carried out a meta-analysis of relevant studies evaluating the effect of metformin therapy on prostate cancer risk.

METHODS

We searched pubmed database (January 1966-February 2014) for case-control and cohort studies that assessed metformin therapy and prostate cancer risk. Two authors independently assessed eligibility and extracted data. Summary RRs was calculated using fixed-effects model or random-effects model. Heterogeneity among studies was examined using Q and I(2) statistics.

RESULTS

We included six cohort studies and four case-control studies in the present meta-analysis, comprising 863,769 participants and 39,073 prostate cancer cases. The pooled RR of prostate cancer in relation to metformin therapy was 0.92 (95% CI: 0.84-1.02, P = 0.112). When we stratified the various studies by study type, we found that metformin therapy was associated with a significant reduced risk of prostate cancer among cohort studies (RR = 0.92, 95% CI [0.87, 0.96], P<0.001); however, no significant association was detected among case-control studies (RR = 0.95, 95% CI [0.78, 1.16], P = 0.632). There was also no indication of publication bias as suggested by Begg's test (P = 0.421) and Egger's test (P = 0.627).

CONCLUSION

Our findings indicate that metformin therapy is not significantly associated with lower prostate cancer risk.

Advances in prostate cancer chemoprevention: a translational perspective

Chemopreventive interventions are steadily emerging as an important aspect of cancer management and control. Herein, we have discussed the major epidemiological and clinical studies advocating the role of androgen inhibitors, flavonoids and antioxidants in preventing prostate cancer (PCa). Androgen inhibitors have lately been discussed not only in treatment of PCa, but also as preventive agents especially after trials with Finasteride and Dutasteride. Flavonoids such as silibinin, green tea polyphenols, genistein, curcumin have shown great promise, but avenues to improve their bioavailability are requisite. Agents with antioxidant potentials like lycopene, selenium, and vitamin E have also been explored. Antioxidant trials have yielded mixed results or benefitted only a subgroup of population, although further studies are needed to establish them as preventive agent. Although a majority of the trials resulted in positive outcomes supporting their role as preventive agents; one should be cautious of neutral or negative results as well. For clinical applicability of these agents, we need to identify the ideal target population, time of intervention, appropriate dosage, and extent of intervention required. Incoherency of data with these agents urges for a stringent study design and thorough interpretation to accurately judge the necessity and feasibility of the preventive measures.

Association between metformin use and risk of prostate cancer and its grade

BACKGROUND

Metformin is commonly prescribed to treat type 2 diabetes. Recent evidence suggests that it may possess antitumoral properties. The aim of this study was to test the association between metformin use and risk of prostate cancer and its grade among men with diabetes.

METHODS

Data were obtained from population-based health-care administrative databases in Ontario, Canada. This retrospective cohort study used a nested case-control approach to examine the relationship between metformin exposure and the risk of prostate cancer within a cohort of incident diabetic men aged 66 years or older. We conducted four case-control analyses, defining case subjects as 1) any prostate cancer, 2) high-grade, 3) low-grade, and 4) biopsy-diagnosed. In each analysis, case subjects were matched to five control subjects on age and cohort entry date. Metformin exposure was determined based on prescriptions before cancer diagnosis, and adjusted odds ratios (aOR) were estimated using conditional logistic regression. All statistical tests were two-sided.

RESULTS

Within our cohort of 119 315 men with diabetes, there were 5306 case subjects with prostate cancer and 26 530 matched control subjects. Within the cancer case subjects, 1104 had high- grade cancer, 1719 had low-grade cancer, and 3524 had biopsy-diagnosed cancer. There was no association between metformin use and risk of any prostate cancer (aOR = 1.03, 95% confidence interval [CI] = 0.96 to 1.1), high-grade cancer (aOR = 1.13, 95% CI = 0.96 to 1.32), low-grade cancer (aOR = 0.94, 95% CI = 0.82 to 1.06), or biopsy-diagnosed cancer (aOR = 0.98, 95% CI = 0.84 to 1.02).

CONCLUSIONS

This large study did not find an association between metformin use and risk of prostate cancer among older men with diabetes, regardless of cancer grade or method of diagnosis.

Statins and cancer: current and future prospects

Statins are inhibitors of 3-hydroxy-methylglutaryl (HMG) CoA reductase. They exhibit effects beyond cholesterol reduction, including anticancer activity. This review presents the effects of statins in vitro and their possible molecular anticancer mechanisms and critically discusses the data regarding the role of statins in cancer prevention. Finally, this review focuses on the use of statins combined with other chemotherapeutics to increase the effectiveness of cancer treatments. Despite rare and inconclusive clinical data, the preclinical results strongly suggest that such combined treatment could be a promising new strategy for the treatment of certain tumor types.

Defining and predicting indolent and low risk prostate cancer

The early detection of asymptomatic prostate cancer has led to the increased incidence of tumours that are unlikely to become symptomatic during life, so called indolent cancers. The prediction of low risk and indolent prostate cancer is needed to avoid overtreatment by unnecessary invasive therapies, and select men for active surveillance. Some of the currently available nomograms predicting these low risk tumours have been validated in independent populations. However, assessment to the compliance with their treatment advises based on the calculation of probability are scarce. The ultimate value of nomograms for the urologic practice can only be assessed by analysing their practical implementation.

Radiolabeled nano-peptides show specificity for an animal model of human PC3 prostate cancer cells

OBJECTIVES

Cancer has been investigated using various pre-targeting techniques or models focusing on radiobombesin analogues; however, both are not offered together. In this study, nano-bombesin labeling by a pre-targeting system was undertaken to develop an alternative approach for prostate tumor treatment.

METHODS

A two-step pre-targeting system utilizing a combination of streptavidin (SA), biotinylated morpholino (B-MORF), biotinylated BBN (B-BBN) with two different spacers (b-Ala and PEG), and a radiolabeled cMORF was evaluated in vitro and in vivo.

RESULTS

Final conjugation conditions consisted of a 1:1:2 ratio of SA:B-MORF:B-BBN, followed by addition of 99mTc-cMORF to compensate for free MORF. In vitro binding experiments with prostate cancer cells (PC-3) revealed that total binding was time-dependent for the Ala spacer but not for the PEG spacer. The highest accumulation (5.06 ± 1.98 %) was achieved with 1 hour of incubation, decreasing as time progressed. Specific binding fell to 1.05 ± 0.35 %. The pre-targeting biodistribution in healthy Swiss mice was measured at different time points, with the best responses observed for 7-h and 15-h incubations. The effector, 99mTc-MAG3-cMORF, was administered 2 h later. Strong kidney excretion was always documented. The greatest tumor uptake was 2.58 ± 0.59 %ID/g at 7 h for B-bAla-BBN, with a region of interest (ROI) value of 3.9 % during imaging. The tumor/blood ratio was low due to the slow blood clearance; however, the tumor/muscle ratio was 5.95.

CONCLUSIONS

The pre-targeting approach with a peptide was a viable concept. Further evaluation with modified sequences of MORF, including less cytosine, and additional test intervals could be worthwhile.