A Systematic Review and Meta-analysis of Associations between Clinical Prostatitis and Prostate Cancer: New Estimates Accounting for Detection Bias

Causal relationship between gut microbiota and prostate cancer contributes to the gut-prostate axis: insights from a Mendelian randomization study

BACKGROUND

Changes in gut microbiota abundance have been linked to prostate cancer development. However, the causality of the gut-prostate axis remains unclear.

METHODS

The genome-wide association study (GWAS) data for gut microbiota sourced from MiBioGen (n = 14,306), alongside prostate cancer summary data from PRACTICAL (n = 140,254) and FinnGen Consortium (n = 133,164). Inverse-variance-weighted (IVW) was mainly used to compute odds ratios (OR) and 95% confidence intervals (Cl), after diligently scrutinizing potential sources of heterogeneity and horizontal pleiotropy via the rigorous utilization of Cochran's Q test, the MR-PRESSO method, and MR-Egger. We used meta-analysis methods in random effects to combine the Mendelian randomization (MR) estimates from the two sources.

RESULTS

The pooled analyses of MR results show that genus Eubacterium fissicatena (OR = 1.07, 95% CI 1.01 to 1.13, P = 0.011) and genus Odoribacter (OR = 1.14, 95% CI 1.01 to 1.27, P = 0.025) were positively associated with prostate cancer. However, genus Adlercreutzia (OR = 0.89, 95% CI 0.83 to 0.96, P = 0.002), Roseburia (OR = 0.90, 95% CI 0.83 to 0.99, P = 0.03), Holdemania (OR = 0.92, 95% CI 0.86 to 0.97, P = 0.005), Flavonifractor (OR = 0.85, 95% CI 0.74 to 0.98, P = 0.024) and Allisonella (OR = 0.93, 95% CI 0.89 to 0.98, P = 0.011) seems to be a protective factor for prostate cancer. Sensitivity analysis found no significant heterogeneity, horizontal pleiotropy, or reverse causal links in all causal associations.

CONCLUSION

This MR study lends support to a causal relationship between genetically predicted gut microbiota and prostate cancer. Research on the gut-prostate axis, along with further multi-omics analyses, holds significant implications for the prevention and treatment of prostate cancer.

Prognostic Factors in Prostate Cancer Associated with Ulcerative Colitis

Ulcerative colitis (UC) has been associated with increased prostate cancer (PCa) risk. However, the mechanisms underlying UC and increased PCa risk remain unclear, and research on this topic is scarce in Japan. We have investigated whether UC is associated with PCa risk in the Japanese population and the risk factors related to PCa among older UC patients. This retrospective single-center cohort study was conducted between January 2010 and April 2022. A total of 68 cases were analyzed, and 9 cases of PCa were observed (13.2%). PCa occurred more frequently in the adult-onset group (8/40, 20.0%) than in the older-onset group with UC (1/28; 3.57%). No significant differences were observed between immunosuppressive therapies and PCa in patients, excluding those with pancolitis-type UC. PCa occurred more frequently in the pancolitis type, and the biologics group had no PCa cases, but the difference was not statistically significant (p = 0.07). This study suggests that pancolitis type and UC onset in middle-aged patients may be risk factors and found that biologics potentially suppress PCa development.

Exploring the role of the inflammasomes on prostate cancer: Interplay with obesity

Obesity is a weight-related disorder characterized by excessive adipose tissue growth and dysfunction which leads to the onset of a systemic chronic low-grade inflammatory state. Likewise, inflammation is considered a classic cancer hallmark affecting several steps of carcinogenesis and tumor progression. In this regard, novel molecular complexes termed inflammasomes have been identified which are able to react to a wide spectrum of insults, impacting several metabolic-related disorders, but their contribution to cancer biology remains unclear. In this context, prostate cancer (PCa) has a markedly inflammatory component, and patients frequently are elderly individuals who exhibit weight-related disorders, being obesity the most prevalent condition. Therefore, inflammation, and specifically, inflammasome complexes, could be crucial players in the interplay between PCa and metabolic disorders. In this review, we will: 1) discuss the potential role of each inflammasome component (sensor, molecular adaptor, and targets) in PCa pathophysiology, placing special emphasis on IL-1β/NF-kB pathway and ROS and hypoxia influence; 2) explore the association between inflammasomes and obesity, and how these molecular complexes could act as the cornerstone between the obesity and PCa; and, 3) compile current clinical trials regarding inflammasome targeting, providing some insights about their potential use in the clinical practice.

Dauricine regulates prostate cancer progression by inhibiting PI3K/AKT-dependent M2 polarization of macrophages

M2 type tumor-associated macrophages, an essential component of the tumor microenvironment (TME), have been proved to contribute to tumor metastasis. Dauricine (Dau) has recently received widespread attention due to its multiple targets and low price. However, the effect of Dau on macrophage polarization of TME remains unclear. In this study, we investigated the effect of Dau on prostate cancer (PCa) metastasis and specifically its correlation to macrophage polarization. Our results showed that Dau efficiently suppressed M2 polarization of macrophages induced by interleukin (IL) -4 and IL-13. Mechanistically, Dau inhibited the activity of PI3K/AKT signaling pathway, which subsequently suppressed macrophage differentiation to M2 type. Importantly, our study indicated that Dau decreased the release of chitinase 3-like protein 1 (CHI3L1) from M2 macrophages, which ultimately inhibited the M2 macrophage-mediated progression of PCa cells in vitro and in vivo. Taken together, our data demonstrated that Dau suppressed M2 polarization of macrophages via downregulation of the PI3K/AKT signaling pathway, in turn, preventing proliferation, epithelial-mesenchymal transition, migration, and invasion of PCa cells. Thus, this study reveals a previously unrecognized function of Dau in inhibition of PCa progression via intervention in M2 polarization of macrophages.

2022 Update on Prostate Cancer Epidemiology and Risk Factors-A Systematic Review

CONTEXT

Prostate cancer (PCa) is one of the most common cancers worldwide. Understanding the epidemiology and risk factors of the disease is paramount to improve primary and secondary prevention strategies.

OBJECTIVE

To systematically review and summarize the current evidence on the descriptive epidemiology, large screening studies, diagnostic techniques, and risk factors of PCa.

EVIDENCE ACQUISITION

PCa incidence and mortality rates for 2020 were obtained from the GLOBOCAN database of the International Agency for Research on Cancer. A systematic search was performed in July 2022 using PubMed/MEDLINE and EMBASE biomedical databases. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines and was registered in PROSPERO (CRD42022359728).

EVIDENCE SYNTHESIS

Globally, PCa is the second most common cancer, with the highest incidence in North and South America, Europe, Australia, and the Caribbean. Risk factors include age, family history, and genetic predisposition. Additional factors may include smoking, diet, physical activity, specific medications, and occupational factors. As PCa screening has become more accepted, newer approaches such as magnetic resonance imaging (MRI) and biomarkers have been implemented to identify patients who are likely to harbor significant tumors. Limitations of this review include the evidence being derived from meta-analyses of mostly retrospective studies.

CONCLUSIONS

PCa remains the second most common cancer among men worldwide. PCa screening is gaining acceptance and will likely reduce PCa mortality at the cost of overdiagnosis and overtreatment. Increasing use of MRI and biomarkers for the detection of PCa may mitigate some of the negative consequences of screening.

PATIENT SUMMARY

Prostate cancer (PCa) remains the second most common cancer among men, and screening for PCa is likely to increase in the future. Improved diagnostic techniques can help reduce the number of men who need to be diagnosed and treated to save one life. Avoidable risk factors for PCa may include factors such as smoking, diet, physical activity, specific medications, and certain occupations.

Presence of HPV in prostate tissue from patients submitted to prostate biopsy

PURPOSE

Prostate cancer (PCa) is the second most frequent cancer among men in the Western population. Infections, such as the one caused by the human papillomavirus (HPV), have been shown to promote inflammation that can lead to the appearance of neoplasms. This study aimed to verify the presence of HPV in neoplastic and non-neoplastic prostate tissue in patients undergoing prostate biopsy and its possible relationship with PCa.

METHODS

Prostate tissue fragments were collected by prostate biopsy and subjected to polymerase chain reaction with primers for the HPV L1 gene to identify the presence of the virus.

RESULTS

Among 162 patients, 10 (6.2%) had HPV and in 152 (93.8%) HPV was not identified in prostate biopsies. HPV was detected in 7/95 (7.4%) of patients with PCa, in 2/55 (3.6%) of patients without PCa, and in no patient with an inconclusive diagnosis of PCa. There was no significant difference (p = 0.487) of HPV presence in the tissue of patients with PCa.

CONCLUSIONS

There were no significant levels of HPV L1 protein in prostate tissue. The findings suggest the absence of HPV oncogenic activity in the prostate tissue of patients with PCa.

The relationship between prior psychiatric diagnosis and brain cancer diagnosis in the U.S. military health system

PURPOSE

Prior research suggested the increased likelihood of brain cancer diagnosis following certain psychiatric diagnoses. This association may result from detection bias or suggest an early sign for brain cancer. This study investigated whether psychiatric illness may be an early manifestation of brain cancer while considering potential effects of detection bias.

METHODS

This case-control study used the data from the Department of Defense's Central Cancer Registry and the Military Health System Data Repository. Four cancer-free controls and one negative-outcome control (cancers not associated with psychiatric illness) were matched to each brain cancer case diagnosed from 1998 to 2013 by age, sex, race, and military status. The groups were compared in the likelihood of having a pre-existing psychiatric diagnosis using conditional logistic regression.

RESULTS

We found a significant association of psychiatric illnesses with brain cancer (Odds Ratio (OR) = 2.63, 95% confidence interval (CI) = 2.18-3.16) and other cancers (OR = 1.80, 95% CI = 1.49-2.19), compared to non-cancer controls. The association was stronger for psychiatric diagnoses within three months before cancer (brain cancer: OR = 26.77, 95% CI = 15.40-46.53; other cancers: OR = 4.12, 95% CI = 1.96-8.65). The association with psychiatric disorders within 3 months were higher for small brain tumors (OR = 128.32, 95% CI = 17.28-952.92 compared to non-cancer controls) while the OR was 2.79 for other cancers (95% CI = 0.86-8.99 compared to non-cancer controls).

CONCLUSION

Our findings suggest an association between diagnosed psychiatric illnesses and subsequent brain cancer diagnosis, which may not be solely explained by detection bias. Psychiatric illness might be a sign for early detection of brain cancer beyond the potential effects of detection bias.

Cellular senescence as a possible link between prostate diseases of the ageing male

Senescent cells accumulate with age in all tissues. Although senescent cells undergo cell-cycle arrest, these cells remain metabolically active and their secretome - known as the senescence-associated secretory phenotype - is responsible for a systemic pro-inflammatory state, which contributes to an inflammatory microenvironment. Senescent cells can be found in the ageing prostate and the senescence-associated secretory phenotype and can be linked to BPH and prostate cancer. Indeed, a number of signalling pathways provide biological plausibility for the role of senescence in both BPH and prostate cancer, although proving causality is difficult. The theory of senescence as a mechanism for prostate disease has a number of clinical implications and could offer opportunities for targeting in the future.

Racial differences in the systemic inflammatory response to prostate cancer

Systemic inflammation may increase risk for prostate cancer progression, but the role it plays in prostate cancer susceptibility is unknown. From a cohort of over 10,000 men who had either a prostate biopsy or transurethral resection that yielded a benign finding, we analyzed 517 incident prostate cancer cases identified during follow-up and 373 controls with one or more white blood cell tests during a follow-up period between one and 18 years. Multilevel, multivariable longitudinal models were fit to two measures of systemic inflammation, neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR), to determine NLR and MLR trajectories associated with increased risk for prostate cancer. For both measures, we found no significant differences in the trajectories by case/control status, however in modeling NLR trajectories there was a significant interaction between race (white or Black and case-control status. In race specific models, NLR and MLR values were consistently higher over time among white controls than white cases while case-control differences in NLR and MLR trajectories were not apparent among Black men. When cases were classified as aggressive as compared to non-aggressive, the case-control differences in NLR and MLR values over time among white men were most apparent for non-aggressive cases. For NLR among white men, significant case-control differences were observed for the entire duration of observation for men who had inflammation in their initial prostate specimen. It is possible that, among white men, monitoring of NLR and MLR trajectories after an initial negative biopsy may be useful in monitoring prostate cancer risk.

Why Do Epidemiologic Studies Find an Inverse Association Between Intraprostatic Inflammation and Prostate Cancer: A Possible Role for Colliding Bias?

Inflammation is an emerging risk factor for prostate cancer based largely on evidence from animal models and histopathologic observations. However, findings from patho-epidemiologic studies of intraprostatic inflammation and prostate cancer have been less supportive, with inverse associations observed in many studies of intraprostatic inflammation and prostate cancer diagnosis. Here, we propose collider stratification bias as a potential methodologic explanation for these inverse findings and provide strategies for conducting future etiologic studies of intraprostatic inflammation and prostate cancer.

Detection of Prostatic Inflammation From Peripheral Lymphocyte Count and Free/Total PSA Ratio in Men With LUTS/BPH

Objective

Identifying biomarkers of prostatic inflammation has been a question of great interest in the development of anti-inflammatory pharmacotherapy for lower urinary tract symptoms suggestive of benign prostatic hyperplasia (LUTS/BPH). Systemic inflammation and serum prostate-specific antigen (PSA) have been linked with prostatic inflammation. This study set out to develop a diagnostic model for prostatic inflammation using clinical and laboratory parameters.

Methods

We included LUTS/BPH patients undergoing transurethral resection of the prostate. The severity of prostatic inflammation was determined by pathological review. Clinical manifestations and preoperative laboratory test results were recorded. We used LASSO regression with 10-fold cross-validation to select variables with the most diagnostic value of prostatic inflammation. Furthermore, we used multivariable logistic regression analysis to develop the diagnostic model, presented in a nomogram. The discrimination, calibration of the post-LASSO diagnostic model, and the model supplemented with clinical parameters were assessed. Decision curve analysis was performed.

Results

A total of 164 patients were included. Of all patients, 97 (59.1%) had no or mild prostatic inflammation, and 67 (40.9%) had moderate to severe prostatic inflammation. A higher peripheral white blood cell count, higher peripheral lymphocyte count, lower free/total (f/t) PSA ratio, and acute urinary retention history were associated with a higher risk of moderate to severe prostatic inflammation. Peripheral lymphocyte count and f/t PSA ratio were selected by the LASSO method and entered into the nomogram. The post-LASSO diagnostic model had an AUC of 0.756 (95% CI: 0.684–0.829) and good calibration. The addition of clinical parameters failed to show incremental diagnostic value. The decision curve analysis demonstrated that the post-LASSO laboratory nomogram was clinically useful.

Conclusion

Our findings demonstrated that peripheral lymphocyte count and f/t PSA ratio appear to be reliable diagnostic markers, based on which we build a clinically useful nomogram for prostatic inflammation. This diagnostic model could facilitate the development of anti-inflammatory pharmacotherapy for LUTS/BPH. Before this model is adopted in clinical practice, future validation is needed to determine its clinical utility.

Is there a correlation between the aggressiveness of chronic asymptomatic prostatitis National Institutes of Health category IV and the Gleason score in patients with prostate cancer?

INTRODUCTION

We evaluated the correlation between the International Society of Urological Pathology (ISUP) grades and the aggressiveness grades of prostate inflammation in newly diagnosed prostate cancer patients with chronic asymptomatic prostatitis National Institiutes of Health (NIH) category IV (CAPNIHIV).

METHODS

The study comprised 357 consecutive patients with prostate cancer in whom a cancer diagnosis had been made via a prostate needle biopsy. Histological sections of the prostate biopsy specimens of the patients were reviewed and scored. Prostatic inflammation was scored using the aggressiveness grade of inflammation. The associations between the ISUP grades and the aggressiveness grades of inflammation were analyzed using logistic regression. The limitations of the study were its retrospective design and the limited number of cases.

RESULTS

In 110 (31%) patients, CAPNIHIV was detected: 56 (51%) patients had a grade 0 aggressiveness score, 34 (31%) patients had a grade 1 aggressiveness score, and 20 (18%) patients had a grade 2 aggressiveness score. The patients who had prostatic inflammation had 1.65 times (95% confidence interval [CI] 1.05-2.61) greater likelihood of a high ISUP grade (grade ≥3) compared with the patients who did not have prostatic inflammation. The association between the ISUP grade and the aggressiveness grade of inflammation was more pronounced for a grade 2 aggressiveness score (n= 20; odds ratio 2.97; 95% CI 1.14-7.71).

CONCLUSIONS

In prostate cancer patients with CAPNIHIV, there was a positive correlation between the inflammation aggressiveness grade and the ISUP grade. The aggressiveness of intraprostatic inflammation may be an important morphological factor affecting the Gleason score.