Vasectomy and risk of prostate cancer: A Mendelian randomization study and confounder analysis

BACKGROUND

Previous reports have shown a potential causal impact of vasectomy on prostate cancer (PCa). The objective of this study was to investigate the association between vasectomy and PCa, while evaluating the influence of confounding factors such as prostate-specific antigen (PSA) screening and body mass index (BMI).

METHODS

Mendelian randomization (MR) study using summary statistics from genome-wide associations of vasectomy (462,933 European ancestry), ever had PSA test (200,410 European ancestry), time since last PSA test (46,104 European ancestry), BMI (152,893 European males) and PCa (79,148 cases, 61,106 controls, European ancestry). This study was conducted using summary statistic data from large, previously described cohorts. Data analyses were conducted from November 2022 to June 2023.

RESULTS

Genetic liability to vasectomy was not associated with PCa (OR = 0.07, 95% CI: 2.95 ×  10-3 , 1.54, p = 0.09). Genetic liability to vasectomy was not associated with ever had PSA test (OR = 1.08, 95% CI: 0.49-2.39, p = 0.83) and time since last PSA test (OR = 2.49, 95% CI: 0.71-8.79, p = 0.16). After controlling for PSA test and BMI, there remains no causal relationship between vasectomy and PCa risk (OR = 5.56 ×  10-4 , 95% CI: 7.29 ×  10-8 , 4.24, p = 0.10). The reverse MR results showed a weak association between PCa and vasectomy patients (OR = 1.00, 95% CI: 1.0003-1.0033, p = 0.02).

CONCLUSION

Based on the available evidence from MR analysis, the current findings did not support vasectomy being a risk factor for PCa. Further work is required to provide additional confirmation and validation of the potential link.

Latent prostate cancer among Japanese males: a bibliometric study of autopsy reports from 1980-2016

Prostate cancer is one of the most common malignancies, but a substantial portion remains latent throughout the patients' lifetime. Analysis of temporal change in the latent prostate cancer pool would be beneficial for clinical decision-making, but longitudinal autopsy studies are rare. We conducted a hand-search of the Annual of Pathological Autopsy Cases in Japan from 1980 to 2016 for cases of latent prostate cancer. Of 570 997 males aged 30 or older, latent prostate cancer was detected in 12 562 patients (2.2%). Proportion of detected cases correlated strongly with 'aging rate', the percentage of population aged 65 or older (squared Pearson's correlation coefficient r2 = 0.972, P value <0.0001). Temporal increase in proportion was also seen in each age group as well. This continuous growth reinforces evidence from past Japanese reports on latent prostate cancer. The rapidly rising ageing rate of Japan may forecast further increase in the latent prostate cancer pool moving forward.

Quality of life in active surveillance for early prostate cancer

Recently, the prevalence of the prostate-specific antigen screening test for early-stage prostate cancer has increased, but this has also resulted in an increase in insignificant cancers. The treatment outcome of early-stage prostate cancer is excellent, but such a radical treatment also leaves the patient with undesired adverse consequences. To resolve such problems, attention should be paid to active surveillance as a modern treatment option. This study aimed to systematically review the literature about quality of life in prostate cancer patients undergoing active surveillance. Evidence was acquired from PubMed databases in March 2019 using quality of life, prostate cancer, well-being, anxiety, depression, stress, outcomes, active surveillance, radiation therapy and radical prostatectomy as keywords. Five clinical active surveillance studies measured health-related quality of life and related psychological factors, and seven compared active surveillance with other treatments (radical therapy and hormone therapy). Active surveillance was superior to radical therapy for urinary and sexual function. Furthermore, most patients who opted for active surveillance showed lower anxiety and fear of progression, whereas health-related quality of life was maintained. Although active surveillance has the advantage of being non-invasive, its diagnosis and follow-up protocols are unreliable. Because such uncertainty can affect patients' quality of life, utilization of imaging modalities, such as magnetic resonance imaging, and the development of new biomarkers are required.

Prostate-specific antigen-based screening in Afro-Caribbean men: a survey of members of the Caribbean Urological Association

Objectives

To examine the attitudes, beliefs and practices of Caribbean urologists regarding prostate-specific antigen (PSA)-based screening in the Caribbean region particularly as it relates to Afro-Caribbean men.

Design

An Internet-based descriptive cross-sectional study using a standardised questionnaire designed to capture information on respondents' attitudes, beliefs and practices towards PSA-based screening was conducted using the online survey tool Survey Monkey among known urologists in the Caribbean, based on the complete mailing list of the membership of the Caribbean Urological Association.

Results

Thirty of the total population of 40 urologists (75%) from nine countries in the Caribbean completed the survey. Twelve (40%) were from Jamaica and eight (26.7%) were from Trinidad. Two-thirds (n = 20) of the urologists believed that PSA-based screening has positively impacted survival in their population and 76.7% (n = 23) supported the PSA-based screening in the Afro-Caribbean male. Seventy-eight percent believed that guidelines from other countries were not applicable to the Caribbean and 63% believed that a regional body should publish its own guidelines. Most supported yearly screening with the PSA and digital rectal examination beginning at age 40 for Afro-Caribbean men but opinion varied regarding PSA-based screening of Indo-Caribbean men. Respondents were unanimous in their belief that there should be an upper age limit for screening, 75 years old being the most commonly reported.

Conclusion

Most Caribbean urologists favour PSA-based screening in Afro-Caribbean men and recommend that Caribbean-specific guidelines need to be drafted.

Prostate-specific antigen screening impacts on biochemical recurrence in patients with clinically localized prostate cancer

OBJECTIVE

To clarify the impact of prostate-specific antigen screening on surgical outcomes of prostate cancer.

METHODS

Patients who underwent radical prostatectomy were divided into two groups according to prostate-specific antigen testing opportunity (group 1, prostate-specific antigen screening; group 2, non-prostate-specific antigen screening). Perioperative clinical characteristics were compared using the Wilcoxon rank-sum and χ² -tests. Cox proportional hazards models were used to identify independent predictors of postoperative biochemical recurrence-free survival.

RESULTS

In total, 798 patients (63.2%) and 464 patients (36.8%) were categorized into groups 1 and 2, respectively. Group 2 patients were more likely to have a higher prostate-specific antigen level and age at diagnosis and larger prostate volume. Clinical T stage, percentage of positive cores and pathological Gleason score did not differ between the groups. The 5-year biochemical recurrence-free survival rate was 83.9% for group 1 and 71.0% for group 2 (P < 0.001). On multivariate analysis, prostate-specific antigen testing opportunity (hazard ratio 2.530; P < 0.001) was an independent predictive factor for biochemical recurrence after surgery, as well as pathological T stage, pathological Gleason score, positive surgical margin and lymphovascular invasion. Additional analyses showed that prostate-specific antigen screening had a greater impact on biochemical recurrence in a younger patients, patients with a high prostate-specific antigen level, large prostate volume and D'Amico high risk, and patients meeting the exclusion criteria of the Prostate Cancer Research International Active Surveillance study.

CONCLUSIONS

Detection by screening results in favorable outcomes after surgery. Prostate-specific antigen screening might contribute to reducing biochemical recurrence in patients with localized prostate cancer.

Can active surveillance really reduce the harms of overdiagnosing prostate cancer? A reflection of real life clinical practice in the PRIAS study

Background

Active surveillance (AS) for low-risk prostate cancer (PCa) appears to provide excellent long-term PCa-specific and overall survival. The choice for AS as initial treatment is mainly based on avoiding side effects from invasive treatment; but AS entails regular check-ups and the possibility of still having to switch or deciding to switch to invasive treatment. Here, we assessed the long-term follow-up data from AS in real life clinical practices.

Methods

Data from the first 500 men, enrolled in PRIAS before July 2008 by 30 centers across 8 countries, were analyzed to provide long-term follow-up results. Men were advised to be regularly examined with prostate-specific antigen (PSA) tests, digital rectal examinations, and prostate biopsies. Men were advised to switch to invasive treatment if they had disease reclassification [Gleason score (GS) ≥3+4 on biopsy, more than two positive biopsy cores, a stage higher than cT2] or a PSA-doubling time of 0-3 years. We assessed time on AS, outcomes and reasons for discontinuing AS, and rates of potential unnecessary biopsies and treatments.

Results

The median follow-up time was 6.5 years. During this period, 325 (65%) men discontinued after a median of 2.3 years and 121 (24%) men had no recent (>1 year) data-update after a median of 7.3 years. The remaining 54 (11%) men were confirmed to be still on AS. Most men discontinued based on protocol advice; 38% had other reasons. During follow-up, 838 biopsy sessions were performed of which 79% to 90% did not lead to reclassification, depending on the criteria. Of the 325 discontinued men, 112 subsequently underwent radical prostatectomy (RP), 126 underwent radiotherapy, 57 switched to watchful waiting (WW) or died, and 30 had another or unknown treatment. RP results were available of 99 men: 34% to 68%, depending on definition, had favorable outcomes; 50% of unfavorable the outcomes occurred in the first 2 years. Of the 30 (6%) men who died, 1 man died due to PCa.

Conclusions

These data, reflecting real life clinical practice, show that more than half of men switched to invasive treatment within 2.3 years, indicating limitations to the extent in which AS is able to reduce the adverse effects of overdiagnosis. Therefore, despite guidelines stating that PCa diagnosis must be uncoupled from treatment, it remains important to avoid overdiagnosing PCa as much as possible.

Metastatic prostate cancer incidence in Australia after amendment to prostate-specific antigen screening guidelines

BACKGROUND

To compare the incidence of newly diagnosed metastatic prostate cancer at an Australian facility pre- and post-publication of the United States Preventive Services Task Force (USPSTF) guidelines and subsequent amendment of the Royal Australian College of General Practitioners Preventive Activities in General Practice guidelines.

METHODS

A retrospective analysis was undertaken by patients with newly diagnosed prostate cancer following transrectal ultrasound-guided biopsy between 2009 and 2014. Patients were divided into two even groups based on whether they had undergone their transrectal ultrasound biopsy pre- (2009-2011) or post- (2013-2014) publication of USPSTF guidelines. Metastatic disease was determined by computed tomography chest, abdomen, pelvis as well as nuclear medicine bone scan. A comparison in the incidence of newly diagnosed metastatic prostate cancer was made.

RESULTS

A total of 130 patients were allocated into each group. In the pre-USPSTF group, 23 out of 130 patients had newly diagnosed metastatic prostatic cancer (17.7%). In the post-USPSTF group, 41 out of 130 (31.5%) had newly diagnosed metastatic prostate cancer (P < 0.05). The mean and median prostate-specific antigen was 15.9 and 9.4 (pre-guideline group) and 33.0 and 9.8 (post-guideline group), respectively (P = 0.02). The post-guidelines group had a higher incidence of low-grade disease (Gleason <7), a decreased incidence of intermediate grade disease (Gleason 7) and a relatively unchanged incidence in high-risk disease (Gleason >7).

CONCLUSION

The incidence of newly diagnosed metastatic prostate cancer nearly doubled in patients referred to our Urology Department post-release of the USPSTF guidelines.

A System Dynamics Model of Serum Prostate-Specific Antigen Screening for Prostate Cancer

Since 2012, US guidelines have recommended against prostate-specific antigen (PSA) screening for prostate cancer. However, evidence of screening benefit from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening trial and the European Randomized Study of Screening for Prostate Cancer has been inconsistent, due partly to differences in noncompliance and contamination. Using system dynamics modeling, we replicated the PLCO trial and extrapolated follow-up to 20 years. We then simulated 3 scenarios correcting for contamination in the PLCO control arm using Surveillance, Epidemiology, and End Results (SEER) incidence and survival data collected prior to the PSA screening era (scenario 1), SEER data collected during the PLCO trial period (1993-2001) (scenario 2), and data from the European trial's control arm (1991-2005) (scenario 3). In all scenarios, noncompliance was corrected using incidence and survival rates for men with screen-detected cancer in the PLCO screening arm. Scenarios 1 and 3 showed a benefit of PSA screening, with relative risks of 0.62 (95% confidence interval: 0.53, 0.72) and 0.70 (95% confidence interval: 0.59, 0.83) for cancer-specific mortality after 20 years, respectively. In scenario 2, however, there was no benefit of screening. This simulation showed that after correcting for noncompliance and contamination, there is potential benefit of PSA screening in reducing prostate cancer mortality. It also demonstrates the utility of system dynamics modeling for synthesizing epidemiologic evidence to inform public policy.

Men's preferences and trade-offs for prostate cancer screening: a discrete choice experiment

OBJECTIVES

Prostate cancer screening using prostate-specific antigen (PSA) remains controversial. In deciding about screening, men must weigh the benefits and harms: little is known about benefit: harm trade-offs men are willing to accept. The objective of this study was to assess men's preferences for PSA screening, and the trade-offs between benefits and harms men are willing to accept when deciding about screening.

METHODS

Preferences of 662 men aged 40-69 were assessed using a discrete choice experiment. PSA screening was described by six attributes: prostate cancer deaths, prostate cancer diagnoses, unnecessary biopsies from false-positive PSA tests, impotence, urinary incontinence/bowel problems and cost. A mixed logit model was used to examine the influence of attributes on men's preferences for PSA testing; benefit: harm trade-offs were also calculated.

RESULTS

Men's preferences were significantly influenced by test characteristics, particularly potential mortality benefit, unnecessary biopsies and likelihood of urinary incontinence or bowel problems; preferences were also influenced by age, prior PSA testing experience and perceived risk of prostate cancer. Men were willing to accept between 65 and 233 of 10 000 extra men with unnecessary biopsies, and between 31 and 72 of 10 000 extra men with incontinence/bowel problems to avoid one prostate cancer death.

CONCLUSIONS

Differences in valuations of attributes and trade-offs acceptable to men of different ages suggest a one size fits all approach to PSA testing, regardless of age, may not reflect men's preferences. Our results can be used by policymakers to ensure screening programmes are in line with men's preferences and by clinicians and patients to facilitate informed discussions of the most relevant benefits and downsides of PSA screening for an individual man.

Estimating age and ethnic variation in the histological prevalence of prostate cancer to inform the impact of screening policies

OBJECTIVES

To estimate histological prevalence of prostate cancer by age and ethnic group.

METHODS

A literature review identified autopsy studies of men without clinical diagnosis of prostate cancer during their lifetime. A total of 25 studies fulfilled the inclusion criteria, and a Bayesian logistic meta-regression was carried out to examine the association between histological prevalence, age by decade and ethnic group (white, African American and Chinese/Japanese).

RESULTS

Histological cancer was estimated to increase with age from 2% (95% confidence interval 1-3%) between 20-29 years-of-age to 69% (95% confidence interval 51-83%) by 90-99 years-of-age in the white ethnic group. The African American group was associated with the highest prevalence of cancer, albeit non-significantly (odds ratio 1.2, 95% confidence interval 0.9-1.5), whereas the Chinese/Japanese group was significantly associated with the lowest prevalence relative to the white group (odds ratio 0.6, 95% confidence interval 0.4-0.9).

CONCLUSIONS

The present study provides an updated and improved analysis of the histological prevalence of prostate cancer. The results confirm ethnicity as a potential predictor of prevalence, but highlight the need for further research in the area. The findings are valuable for understanding the epidemiology and natural history of prostate cancer across ethnicities, and increasing the body of evidence aimed at estimating benefits and risks associated with prostate cancer screening programs.