The Relationship Between Prostate Cancer and Metformin Consumption: A Systematic Review and Meta-analysis Study

Obesity and main urologic cancers: Current systematic evidence, novel biological mechanisms, perspectives and challenges

Urologic cancers (UC) account for 13.1% of all new cancer cases and 7.9% of all cancer-related deaths. A growing body of evidence has indicated a potential causal link between obesity and UC. The aim of the present review is to appraise in a critical and integrative manner evidence from meta-analyses and mechanistic studies on the role of obesity in four prevalent UC (kidney-KC, prostate-PC, urinary bladder-UBC, and testicular cancer-TC). Special emphasis is given on Mendelian Randomization Studies (MRS) corroborating a genetic causal association between obesity and UC, as well as on the role of classical and novel adipocytokines. Furthermore, the molecular pathways that link obesity to the development and progression of these cancers are reviewed. Available evidence indicates that obesity confers increased risk for KC, UBC, and advanced PC (20-82%, 10-19%, and 6-14%, respectively), whereas for TC adult height (5-cm increase) may increase the risk by 13%. Obese females tend to be more susceptible to UBC and KC than obese males. MRS have shown that a higher genetic-predicted BMI may be causally linked to KC and UBC but not PC and TC. Biological mechanisms that are involved in the association between excess body weight and UC include the Insulin-like Growth Factor axis, altered availability of sex hormones, chronic inflammation and oxidative stress, abnormal secretion of adipocytokines, ectopic fat deposition, dysbiosis of the gastrointestinal and urinary tract microbiomes and circadian rhythm dysregulation. Anti-hyperglycemic and non-steroidal anti-inflammatory drugs, statins, and adipokine receptor agonists/antagonists show potential as adjuvant cancer therapies. Identifying obesity as a modifiable risk factor for UC may have significant public health implications, allowing clinicians to tailor individualized prevention strategies for patients with excess body weight.

Systematic review of antitumour efficacy and mechanism of metformin activity in prostate cancer models

Metformin, the first line pharmacotherapy for type 2 diabetes has demonstrated favourable effects in prostate cancer (PCa) across a range of studies evaluating PCa patient outcomes amongst metformin users. However, a lack of rigorously conducted prospective studies has stalled clinical use in this setting. Despite multiple studies evaluating the mechanisms underpinning antitumour effects of metformin in PCa, to date, no reviews have compared these findings. This systematic review and meta-analysis consolidates the mechanisms accounting for the antitumour effect of metformin in PCa and evaluates the antitumour efficacy of metformin in preclinical PCa studies. Data were obtained through Medline and EMBASE, extracted by two independent assessors. Risk of bias was assessed using the TOXR tool. Meta-analysis compared in vivo reductions of PCa tumour volume with metformin. In total, 447 articles were identified with 80 duplicates, and 261 articles excluded based on eligibility criteria. The remaining 106 articles were assessed and 71 excluded, with 35 articles included for systematic review, and eight included for meta-analysis. The mechanisms of action of metformin regarding tumour growth, viability, migration, invasion, cell metabolism, and activation of signalling cascades are individually discussed. The mechanisms by which metformin inhibits PCa cell growth are multimodal. Metformin regulates expression of multiple proteins/genes to inhibit cellular proliferation, cell cycle progression, and cellular invasion and migration. Published in vivo studies also conclusively demonstrate that metformin inhibits PCa growth. This highlights the potential of metformin to be repurposed as an anticancer agent, warranting further investigation of metformin in the setting of PCa.

Family history, obesity, urological factors and diabetic medications and their associations with risk of prostate cancer diagnosis in a large prospective study

Background

Prostate cancer (PC) aetiology is unclear. PC risk was examined in relation to several factors in a large population-based prospective study.

Methods

Male participants were from Sax Institute’s 45 and Up Study (Australia) recruited between 2006 and 2009. Questionnaire and linked administrative health data from the Centre for Health Record Linkage and Services Australia were used to identify incident PC, healthcare utilisations, Prostate Specific Antigen (PSA) testing reimbursements and dispensing of metformin and benign prostatic hyperplasia (BPH) prescriptions. Multivariable Cox and Joint Cox regression analyses were used to examine associations by cancer spread, adjusting for various confounders.

Results

Of 107,706 eligible men, 4257 developed incident PC up to end 2013. Risk of PC diagnosis increased with: PC family history (versus no family history of cancer; HR_adjusted = 1.36; 95% CI:1.21–1.52); father and brother(s) diagnosed with PC (versus cancer-free family history; HR_adjusted = 2.20; 95% CI:1.61–2.99); severe lower-urinary-tract symptoms (versus mild; HR_adjusted = 1.77; 95% CI:1.53–2.04) and vasectomy (versus none; HR_adjusted = 1.08; 95% CI:1.00–1.16). PC risk decreased with dispensed prescriptions (versus none) for BPH (HR_adjusted = 0.76; 95% CI:0.69–0.85) and metformin (HR_adjusted = 0.57; 95% CI:0.48–0.68). Advanced PC risk increased with vasectomy (HR_adjusted = 1.28; 95% CI:1.06–1.55) and being obese (versus normal weight; HR_adjusted = 1.31; 95% CI:1.01–1.69).

Conclusion

Vasectomy and obesity are associated with an increased risk of advanced PC. The reduced risk of localised and advanced PC associated with BPH, and diabetes prescriptions warrants investigation.

Prostate cancer genetic propensity risk score may modify the association between this tumour and type 2 diabetes mellitus (MCC-Spain study)

BACKGROUND

Some studies have reported an inverse association between type 2 diabetes mellitus (T2DM) and prostate cancer (PCa), but results on this issue are still inconsistent. In this study, we evaluate whether this heterogeneity might be related to differences in this relationship by tumour or by individual genetic susceptibility to PCa.

METHODS

We studied 1047 incident PCa cases and 1379 randomly selected controls, recruited in 7 Spanish provinces for the population-based MCC-Spain case-control. Tumour were classified by aggressiveness according to the International Society of Urological Pathology (ISUP), and we constructed a PCa polygenic risk score (PRS) as proxy for genetic susceptibility. The epidemiological questionnaire collected detailed self-reported data on T2DM diagnosis and treatment. The association between T2DM status and PCa was studied by fitting mixed logistic regression models, and, for its association by aggressiveness of PCa, with multinomial logistic regression models. To evaluate the possible modulator role of PRS in this relationship, we included the corresponding interaction term in the model, and repeated the analysis stratified by PRS tertiles.

RESULTS

Globally, our results showed an inverse association between T2DM and overall PCa limited to grade 1 tumours (OR_ISUP = 1: 0.72; 95% CI: 0.53-0.98), which could be compatible with a detection bias. However, PCa risk also varied with duration of diabetes treatment -inversely to metformin and positively with insulin-, without differences by aggressiveness. When we considered genetic susceptibility, T2DM was more strongly associated with lower PCa risk in those with lower PRS (OR_{tertile 1}: 0.31; 95% CI: 0.11-0.87), independently of ISUP grade.

CONCLUSIONS

Our findings reinforce the need to include aggressiveness and susceptibility of PCa, and T2DM treatments in the study of the relationship between both diseases.

Metformin Treatment Among Men With Diabetes and the Risk of Prostate Cancer: A Population-Based Historical Cohort Study

There is conflicting evidence regarding the association between metformin treatment and prostate cancer risk in diabetic men. We investigated this association in a population-based Israeli cohort of 145,617 men aged 21–89 years with incident diabetes who were followed over the period 2002–2012. We implemented a time-dependent covariate Cox model, using weighted cumulative exposure to relate metformin history to prostate cancer risk, adjusting for use of other glucose-lowering medications, age, ethnicity, and socioeconomic status. To adjust for time-varying glucose control variables, we used inverse probability weighting of a marginal structural model. With 666,553 person-years of follow-up, 1,592 men were diagnosed with prostate cancer. Metformin exposure in the previous year was positively associated with prostate cancer risk (per defined daily dose; without adjustment for glucose control, hazard ratio (HR) = 1.53 (95% confidence interval (CI): 1.19, 1.96); with adjustment, HR = 1.42 (95% CI: 1.04, 1.94)). However, exposure during the previous 2–7 years was negatively associated with risk (without adjustment for glucose control, HR = 0.58 (95% CI: 0.37, 0.93); with adjustment, HR = 0.60 (95% CI: 0.33, 1.09)). These positive and negative associations with previous-year and earlier metformin exposure, respectively, need to be confirmed and better understood.

Metformin: Sex/Gender Differences in Its Uses and Effects—Narrative Review

Metformin (MTF) occupies a major and fundamental position in the therapeutic management of type 2 diabetes mellitus (T2DM). Gender differences in some effects and actions of MTF have been reported. Women are usually prescribed lower MTF doses compared to men and report more gastrointestinal side effects. The incidence of cardiovascular events in women on MTF has been found to be lower to that of men on MTF. Despite some promising results with MTF regarding pregnancy rates in women with PCOS, the management of gestational diabetes, cancer prevention or adjunctive cancer treatment and COVID-19, most robust meta-analyses have yet to confirm such beneficial effects.

Effect of precise nursing service mode on postoperative urinary incontinence prevention in patients with prostate disease

BACKGROUND

Patients with benign prostatic disease often experience detrusor morphological changes and dysfunction. In severe cases, it leads to bladder detrusor dysfunction, resulting in dysuria, frequent urination, urgent urination, incomplete urination, and other symptoms including renal function injury. An operation to restore normal urination function and to control postoperative complications, as far as possible, is the most common method for benign prostatic disease.

AIM

To observe the effect of precise nursing service mode on postoperative urinary incontinence prevention in patients with prostate disease.

METHODS

In total, 130 patients diagnosed with benign prostatic disease, from January 2018 to June 2021, in our hospital, were selected and divided into observation and control groups according to their treatment options. Sixty-five cases in the control group were given routine nursing mode intervention and 65 cases in the observation group received precise nursing service mode intervention. The intervention with the observation group included psychological counseling about negative emotions, pelvic floor exercises, and post-hospital discharge care. The complications of the two groups were counted, and the general postoperative conditions of the two groups were recorded. The urinary flow dynamics indexes of the two groups were detected, and differences in clinical international prostate system score (IPSS) and urinary incontinence quality of life questionnaire (I-QOL) scores were evaluated.

RESULTS

Postoperative exhaust time (18.65 ± 3.23 h and 24.63 ± 4.51 h), the time of indwelling catheter (4.85 ± 1.08 d and 5.63 ± 1.24 d), and hospitalization time (8.78 ± 2.03 d and 10.23 ± 2.28 d) in the observation group were lower than in the control group. The difference was statistically significant (P < 0.05). After the operation, the maximum urinary flow rate (Qmax) increased (P < 0.05), the residual urine volume (RUV) decreased (P < 0.05), and the maximum closed urethral pressure (MUCP) was not statistically significant (P > 0.05) compared to pre-operation. The Qmax of the observation group was higher than that of the control group, while the RUV was lower than that of the control group. There was no significant difference in MUCP between the observation and control groups (P > 0.05). The I-QOL score of the two groups improved (P < 0.05), and the IPSS decreased (P < 0.05). After the operation, the I-QOL score of the observation group was higher than that of the control group, and the IPSS was lower than that of the control group (P < 0.05). There were no significant differences in the incidence of urethral injury (1.54% and 3.08%), bladder spasm (0.00% and 1.54%), and secondary bleeding (1.54% and 4.62) between the observation and control groups (P > 0.05).

CONCLUSION

The precise nursing service mode can reduce the incidence of postoperative urinary incontinence in patients with prostate disease, thus improving postoperative urodynamics and rehabilitation, and quality of life.

The Influence of Anti-Diabetic Drugs on Prostate Cancer

The incidences of prostate cancer (PC) and diabetes are increasing, with a sustained trend. The occurrence of PC and type 2 diabetes mellitus (T2DM) is growing with aging. The correlation between PC occurrence and diabetes is noteworthy, as T2DM is correlated with a reduced risk of incidence of prostate cancer. Despite this reduction, diabetes mellitus increases the mortality in many cancer types, including prostate cancer. The treatment of T2DM is based on lifestyle changes and pharmacological management. Current available drugs, except insulin, are aimed at increasing insulin secretion (sulfonylureas, incretin drugs), improving insulin sensitivity (biguanides, thiazolidinediones), or increasing urinary glucose excretion (gliflozin). Comorbidities should be taken into consideration during the treatment of T2DM. This review describes currently known information about the mechanism and impact of commonly used antidiabetic drugs on the incidence and progression of PC. Outcomes of pre-clinical studies are briefly presented and their correlations with available clinical trials have also been observed. Available reports and meta-analyses demonstrate that most anti-diabetic drugs do not increase the risk during the treatment of patients with PC. However, some reports show a potential advantage of treatment of T2DM with specific drugs. Based on clinical reports, use of metformin should be considered as a therapeutic option. Moreover, anticancer properties of metformin were augmented while combined with GLP-1 analogs.

Main Inflammatory Cells and Potentials of Anti-Inflammatory Agents in Prostate Cancer

Prostate cancer is the most common type of cancer and the leading cause of cancer deaths among men in many countries. Preventing progression is a major concern for prostate cancer patients on active surveillance, patients with recurrence after radical therapies, and patients who acquired resistance to systemic therapies. Inflammation, which is induced by various factors such as infection, microbiome, obesity, and a high-fat diet, is the major etiology in the development of prostate cancer. Inflammatory cells play important roles in tumor progression. Various immune cells including tumor-associated neutrophils, tumor-infiltrating macrophages, myeloid-derived suppressor cells, and mast cells promote prostate cancer via various intercellular signaling. Further basic studies examining the relationship between the inflammatory process and prostate cancer progression are warranted. Interventions by medications and diets to control systemic and/or local inflammation might be effective therapies for prostate cancer progression. Epidemiological investigations and basic research using human immune cells or mouse models have revealed that non-steroidal anti-inflammatory drugs, metformin, statins, soy isoflavones, and other diets are potential interventions for preventing progression of prostate cancer by suppressing inflammation. It is essential to evaluate appropriate indications and doses of each drug and diet.

Metformin use and prostate cancer risk: A meta-analysis of cohort studies

BACKGROUND

The relationship between metformin use and the risk of prostate cancer is still inconclusive. Therefore, we performed a systematic review and meta-analysis of all eligible cohort studies to evaluate a potential association of metformin use with prostate cancer risk.

METHODS

A comprehensive literature search was performed in PubMed and Web of Science databases through July 2018. A DerSimonian and Laird random-effects model was applied to calculate the pooled relative risk (RR) and its 95% confidence interval (CI).

RESULTS

Eighteen cohort or nested case-control studies were included in this study with a total of 52,328 cases. In a random-effect pooled analysis, metformin use was not significantly associated with the risk of prostate cancer (RR 0.97, 95% CI 0.80-1.16, P = .711). Statistically significant heterogeneity was identified among included studies (P < .001, I = 98.1%). Sensitivity analysis indicated that no single study dominated the pooled RR.

CONCLUSION

The present large meta-analysis of cohort studies did not find an association between metformin use and prostate cancer risk.