Statins are Associated With Increased Biochemical Recurrence After Radical Prostatectomy in Diabetic Men but no Association was Seen in Men also Taking Metformin: Results From the SEARCH Database

Effect of metformin on incidence, recurrence, and mortality in prostate cancer patients: integrating evidence from real-world studies

PURPOSE

Metformin has been suggested to reduce the risk of cancer. However, previous studies have been inconsistent regarding the relationship between metformin use and the risk of occurrence of prostate cancer (PCa). The purpose of this study was to assess the effect of metformin on clinical outcomes in patients with PCa in a meta-analysis and to explore the possible dose-response relationship.

METHODS

A systematic literature search was conducted in 10 electronic databases and 4 registries. The combined relative risks (RRs) were calculated using a random-effects model with 95% confidence interval (CIs) to assess the effect of metformin on the risk of PCa. Relevant subgroup analyses and sensitivity analyses were performed.

RESULTS

The across studies results show that metformin use associated with lower incidence of PCa (RR: 0.82, 95% CI: 0.74-0.91). Metformin use was also found to reduce PCa recurrence, but the results were not statistically significant (RR: 0.97, 95% CI: 0.81-1.15). Metformin use was not associated with PCa mortality (RR: 0.94, 95% CI: 0.81-1.09). The results of subgroup analyses indicated that the type of study was a cohort study and the population came from both Asia and Europe showed that taking metformin reduced the incidence of PCa. A linear correlation was found between the duration of metformin use and its protective effect.

CONCLUSIONS

This meta-analysis revealed an independent correlation between metformin use and reduced incidence of PCa. Metformin use was not associated with either PCa recurrence rate or mortality. Furthermore, the effect of metformin on PCa incidence was found to be related to duration.

Statin use and outcomes of oncological treatment for castration-resistant prostate cancer

To compare the effect of statin use in relation to castration-resistant prostate cancer (CRPC) treatment, we assessed the risk of ADT-treated PCa-patients to initiate CRPC treatment by statin use and the outcomes of CRPC treatment by statin use. Our study cohort consisted of 1169 men who participated in the Finnish Randomized Study of Screening for Prostate Cancer (FinRSPC) and initiated androgen deprivation therapy (ADT) during the follow-up (1996-2017). Statin use was associated with slightly decreased risk of initiating CRPC treatment (HR 0.68; 95% CI 0.47-0.97) with a 5.7 years' median follow-up until CRPC for non-users and 7.5 years for statin users. The risk of discontinuation of first or second line CRPC treatment due to inefficacy was not modified by statin use and the results remained similar in subgroup analysis assessing separately patients treated with taxans or androgen receptor signaling inhibitors. We observed an inverse association between statin use and the risk of initiation of the CRPC treatment. No beneficial risk modification by statin use during CRPC treatment was observed. These results suggest that statins might be beneficial during hormone-sensitive phase but not in the later phases of prostate cancer treatment.

Diabetes and Prostate Cancer Outcomes in Men with Nonmetastatic Castration-Resistant Prostate Cancer: Results from the SEARCH Cohort

BACKGROUND

The prognosis of diabetic men with advanced prostate cancer is poorly understood and understudied. Hence, we studied associations between diabetes and progression to metastases, prostate cancer-specific mortality (PCSM) and all-cause mortality (ACM) in men with nonmetastatic castration-resistant prostate cancer (nmCRPC).

METHODS

Data from men diagnosed with nmCRPC between 2000 and 2017 at 8 Veterans Affairs Health Care Centers were analyzed using Cox regression to determine HRs and 95% confidence intervals (CI) for associations between diabetes and outcomes. Men with diabetes were classified according to: (i) ICD-9/10 codes only, (ii) two HbA1c values > 6.4% (missing ICD-9/10 codes), and (iii) all diabetic men [(i) and (ii) combined].

RESULTS

Of 976 men (median age: 76 years), 304 (31%) had diabetes at nmCRPC diagnosis, of whom 51% had ICD-9/10 codes. During a median follow-up of 6.5 years, 613 men were diagnosed with metastases, and 482 PCSM and 741 ACM events occurred. In multivariable-adjusted models, ICD-9/10 code-identified diabetes was inversely associated with PCSM (HR, 0.67; 95% CI, 0.48-0.92) while diabetes identified by high HbA1c values (no ICD-9/10 codes) was associated with an increase in ACM (HR, 1.41; 95% CI, 1.16-1.72). Duration of diabetes, prior to CRPC diagnosis was inversely associated with PCSM among men identified by ICD-9/10 codes and/or HbA1c values (HR, 0.93; 95% CI, 0.88-0.98).

CONCLUSIONS

In men with late-stage prostate cancer, ICD-9/10 'code-identified' diabetes is associated with better overall survival than 'undiagnosed' diabetes identified by high HbA1c values only.

IMPACT

Our data suggest that better diabetes detection and management may improve survival in late-stage prostate cancer.

Clinical, Cellular, and Molecular Evidence of the Additive Antitumor Effects of Biguanides and Statins in Prostate Cancer

CONTEXT

Prostate cancer (PCa) is one of the leading causes of cancer-related death among the male population worldwide. Unfortunately, current medical treatments fail to prevent PCa progression in a high percentage of cases; therefore, new therapeutic tools to tackle PCa are urgently needed. Biguanides and statins have emerged as antitumor agents for several endocrine-related cancers.

OBJECTIVE

To evaluate: (1) the putative in vivo association between metformin and/or statins treatment and key tumor and clinical parameters and (2) the direct effects of different biguanides (metformin/buformin/phenformin), statins (atorvastatin/simvastatin/lovastatin), and their combination, on key functional endpoints and associated signalling mechanisms.

METHODS

An exploratory/observational retrospective cohort of patients with PCa (n = 75) was analyzed. Moreover, normal and tumor prostate cells (normal [RWPE-cells/primary prostate cell cultures]; tumor [LNCaP/22RV1/PC3/DU145 cell lines]) were used to measure proliferation/migration/tumorsphere-formation/signalling pathways.

RESULTS

The combination of metformin+statins in vivo was associated to lower Gleason score and longer biochemical recurrence-free survival. Moreover, biguanides and statins exerted strong antitumor actions (ie, inhibition of proliferation/migration/tumorsphere formation) on PCa cells, and that their combination further decreased; in addition, these functional parameters compared with the individual treatments. These actions were mediated through modulation of key oncogenic and metabolic signalling pathways (ie, AR/mTOR/AMPK/AKT/ERK) and molecular mediators (MKI67/cMYC/androgen receptor/cell-cycle inhibitors).

CONCLUSIONS

Biguanides and statins significantly reduced tumor aggressiveness in PCa, with this effect being more potent (in vitro and in vivo) when both compounds are combined. Therefore, given the demonstrated clinical safety of biguanides and statins, our results suggest a potential therapeutic role of these compounds, especially their combination, for the treatment of PCa.

Individual and joint effects of metformin and statins on mortality among patients with high-risk prostate cancer

BACKGROUND

Pre-clinical studies suggest that metformin and statins may delay prostate cancer (PCa) metastases; however, data in humans are limited. To the best of our knowledge, this is the first human study aimed to quantify the individual and joint effects of statin and metformin use among patients with high-risk PCa.

METHODS

This population-based retrospective cohort study identified patients from the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. Exposure to metformin and statins was ascertained from Medicare Prescription Drug Event files. The association with all-cause and PCa mortality were evaluated using Cox proportional hazard model with competing causes of death, where propensity scores were used to adjusted imbalances in covariates across groups.

RESULTS

Based on 12 700 patients with high-risk PCa, statin alone or in combination with metformin was significantly associated with reduced all-cause mortality (Hazard Ratio [HR]: 0.89; 95% Confidence Interval [CI]: 0.83, 0.96; and HR: 0.75; 95% CI, 0.67-0.83, respectively) and PCa mortality (HR, 0.80; 95% CI: 0.69, 0.92) and 0.64; 95% CI, d 0.51-0.81, respectively. The effects were more pronounced in post-diagnostic users: combination use of metformin/statins was associated with a 32% reduction in all-cause mortality (95% CI, 0.57-0.80), and 54% reduction in PCa mortality (95% CI, 0.30-0.69). No significant association of metformin alone was observed with either all-cause mortality or PCa mortality.

CONCLUSIONS

Statin use alone or in combination with metformin was associated with lower all-cause and PCa mortality among high-risk patients, particularly in post-diagnostic settings; further studies are warranted.

Associations among statins, preventive care, and prostate cancer mortality

BACKGROUND

Increasing evidence indicates an association between statins and reduced prostate cancer-specific mortality (PCSM). However, significant bias may exist in these studies. One particularly challenging bias to assess is the healthy user effect, which may be quantified by screening patterns. We aimed to evaluate the association between statin use, screening, and PCSM in a dataset with detailed longitudinal information.

METHODS

We used the Veterans Affairs Informatics and Computing Infrastructure to assemble a cohort of patients diagnosed with prostate cancer (PC) between 2000 and 2015. We collected patient-level demographic, comorbidity, and tumor data. We also assessed markers of preventive care utilization including cholesterol and prostate specific antigen (PSA) screening rates. Patients were considered prediagnosis statin users if they had at least one prescription one or more years prior to PC diagnosis. We evaluated PCSM using hierarchical Fine-Gray regression models and all-cause mortality (ACM) using a cox regression model.

RESULTS

The final cohort contained 68,432 men including 40,772 (59.6%) prediagnosis statin users and 27,660 (40.4%) nonusers. Prediagnosis statin users had higher screening rates than nonusers for cholesterol (90 vs. 69%, p < 0.001) and PSA (76 vs. 67%, p < 0.001). In the model which excluded screening, prediagnosis statin users had improved PCSM (SHR 0.90, 95% CI 0.84-0.97; p = 0.004) and ACM (HR 0.96, 95% CI 0.93-0.99; p = 0.02). However, after including cholesterol and PSA screening rates, prediagnosis statin users and nonusers showed no differences in PCSM (SHR 0.98, 95% CI 0.91-1.06; p = 0.59) or ACM (HR 1.02, 95% CI 0.98-1.05; p = 0.25).

CONCLUSION

We found that statin users tend to have more screening than nonusers. When we considered screening utilization, we observed no relationship between statin use before a prostate cancer diagnosis and prostate cancer mortality.

Access and concentrations of atorvastatin in the prostate in men with prostate cancer

BACKGROUND

Statins have anticancer effects on prostate cancer both in vitro and in vivo. It is unclear whether this is due to systemic cholesterol-lowering or direct local growth inhibition in the prostate. It is also unclear whether statins can access the prostate; lipophilic statins could, in theory, pass lipid-enriched cell membranes by passive diffusion. However, statin concentrations in the human prostate have not been measured before.

METHODS

The study population was based on a randomized clinical trial where 158 men with prostate cancer were randomized to use 80 mg atorvastatin (ATV) or placebo daily for a median of 27 days before radical prostatectomy. ATV and atorvastatin lactone (ATV-Lactone) concentrations in the plasma and in the prostate were measured with mass spectrometry in men randomized to the ATV arm. Linear trends between intraprostatic concentration and plasma concentration, body mass index, age, and duration of intervention were examined. The relative tissue concentrations of ATV and ATV-Lactone were calculated in prostatic tissue and plasma to evaluate drug homeostasis. Subgroup analyses were stratified by tumor and population characteristics.

RESULTS

The analysis involved a total of 55 men. When limited to men whose tissue concentrations of ATV was measurable (n = 28, 50%), median ATV concentration was 212% higher in the tissue (median concentration 17.6 ng/g) compared to the plasma (median concentration 3.6 ng/mL). Also, ATV-L concentration was 590% higher in the tissue as compared to the plasma concentration. No statistically significant linear trends between the plasma and tissue concentrations were observed. When comparing the relative concentration of atorvastatin lactone over ATV, the concentrations were in balance in the plasma, In the prostate, however, the relative concentration of atorvastatin lactone was 57% lower compared to ATV (P = .009 for the difference between prostate tissue and plasma). No effect modification by tumor or population characteristics was observed.

CONCLUSIONS

Measurable ATV concentrations in the prostate support ATV's ability to access the prostate from the circulation. ATV may accumulate in the prostate as intraprostatic concentrations are elevated compared to the plasma concentration.