Are metformin, statin and aspirin use still associated with overall mortality among colorectal cancer patients with diabetes if adjusted for one another?

Association of metformin and statin uses with the prognosis of colon cancer: a meta-analysis

BACKGROUND

Metformin and statins are commonly used globally for the treatment of type 2 diabetes mellitus and dyslipidemia, respectively. Recently, multiple novel pathways have been discovered, which may contribute to the treatment of various types of cancer. Several meta-analysis studies have reported that the use of metformin or statins is associated with a lower risk of colon cancer compared to nonusers. In this study, our aim was to perform a meta-analysis and investigate the prognostic roles of these two medications in colon cancer.

METHODS

To identify relevant articles, literature searches were performed in the PubMed and Web of Science databases using a combination of keywords related to metformin, statins and colon cancer prognosis until August 2023. The study utilized STATA 12.0 software (Stata Corporation, College Station, Texas, USA) to compute all the hazard ratios (HRs) and 95% confidence intervals (CIs) regarding the association between metformin or statin uses and prognostic-related outcomes.

RESULTS

Our analysis revealed that the use of metformin was associated with a significantly lower overall mortality of colon cancer (HR = 0.63; 95% CI = 0.51-0.77; I2  = 94.9%; P  < 0.001), as well as lower cancer-specific mortality of colon cancer (HR = 0.68; 95% CI = 0.50-0.94; I2  = 91.9%; P  < 0.001). Similarly, the use of statins was also associated with a lower overall mortality of colon cancer (HR = 0.68; 95% CI = 0.60-0.78; I2  = 93.8%; P  < 0.001), as well as a lower cancer-specific mortality of colon cancer (HR = 0.74; 95% CI = 0.67-0.81; I2  = 82.2%; P  < 0.001).

CONCLUSION

Our meta-analysis study suggests that statins and metformin may have potential as adjuvant agents with significant benefits in the prognosis of colon cancer.

Prognostic value of metformin in cancers: An updated meta-analysis based on 80 cohort studies

BACKGROUND

Experiments have shown that metformin can inhibit cancer cell growth, but clinical observations have been inconsistent, so we pooled the currently available data to evaluate the impact of metformin on cancer survival and progression.

METHODS

PubMed, web of science, Embase, and Cochrane databases were searched. Pooled hazard ratios (HRs) were identified using a random-effects model to estimate the strength of the association between metformin and survival and progression in cancer patients.

RESULTS

We incorporated 80 articles published from all databases which satisfied the inclusion criterion. It showed that metformin was associated with better overall survival (hazard ratio [HR] = 0. 81; 95% confidence interval [CI]: [0.77-0.85]) and cancer-specific survival (HR = 0.79; 95% CI: [0.73-0.86]), and metformin was associated with progression-free survival (HR = 0.76; 95% CI: [0.66-0.87]). In patients with diabetes mellitus, the HR of overall survival was 0.79(95% CI: [0.75-0.83]), progression-free survival was 0.72(95% CI: [0.60-0.85]), and the cancer-specific survival was 0.76(95% CI: [0.68-0.86]). It was proposed that metformin can improve the prognosis of cancer patients with diabetes mellitus.

CONCLUSION

Based on cohort studies, metformin therapy has potential survival benefits for patients with malignancy, especially with the greatest benefits seen in breast cancer on overall survival, progression-free survival, and cancer-specific survival. And metformin also showed potential benefits in cancer-specific survival in colorectal and prostate cancer.

The Association of Metformin, Other Antidiabetic Medications and Statins on the Prognosis of Rectal Cancer in Patients with Type 2 Diabetes: A Retrospective Cohort Study

Metformin and statin use have been associated with an improved prognosis for colorectal cancer in persons with type 2 diabetes (T2D). Data regarding rectal cancer (RC) have been inconclusive; therefore, we investigated the issue with high-quality data and a robust study design. We identified 1271 eligible patients with T2D and incident RC between 1998 and 2011 from the Diabetes in Finland (FinDM) database. Cox models were fitted for cause-specific mortality rates to obtain adjusted estimates of the hazard ratios (HR) with 95% confidence intervals (CI) in relation to use of antidiabetic medication (ADM) and statins before the RC diagnosis and for post-diagnostic use in a time-dependent exposure manner. No sufficient evidence was found for either pre- or post-diagnostic metformin use and RC mortality (HR 0.96, 95% CI 0.67–1.38, and 0.70, 95% CI 0.45–1.10, respectively) when compared to other oral ADMs. Both pre- and post-diagnostic statin use appeared to be inversely associated with mortality from RC (HR 0.77 95% CI 0.63–0.94, and 0.57, 95% CI 0.42–0.78, respectively). Our study was inconclusive as to the association of metformin use with the prognosis of RC, but statin use was found to predict reduced mortality, both from RC and from other causes of death in persons with T2D.

Clinicopathological Characteristics and Overall 5-Year Survival of Colorectal Cancer: A Retrospective Study

Colorectal cancer (CRC) is the third leading cause of cancer-related death. We aimed to investigate the clinicopathological characteristics and 5-year survival in CRC. This retrospective study reviewed King Abdulaziz University Hospital records from 2009 to 2019. Tumor staging was performed using Dukes’ pathological classification. Additionally, we measured the frequency of qualitative data and performed the chi-square and Mann−Whitney U-tests. Kaplan−Meier analysis was performed to calculate overall survival. Of the 574 included patients (age (mean ± standard deviation), 55.51 ± 14.28 years), 43.2% were Saudis, and most were male (58.7%). The rectum was the most common location of CRC (30.8%); 33.1% of patients presented with abdominal pain. The dominant histological variant was mucinous adenocarcinoma (95.5%). Age at diagnosis was significantly associated with Dukes’ staging; 36.3% of individuals aged <50 years had Dukes’ D stage. The 5-year survival rate was 47.9%. Better survival was noted for those of Saudi nationality, those with Dukes’ A stage, and those who were overweight (51.6%, 56.3%, and 46.8%, respectively). Significantly better survival was seen in Saudi patients due to accessible healthcare and in overweight patients due to better treatment tolerance. The outcome of CRC was not related to sex or metformin use in patients with diabetes mellitus.

Neoadjuvant therapy of metformin is associated with good tumor response after preoperative concurrent chemoradiotherapy for rectal cancer

Metformin is associated with good tumor response in preoperative concurrent chemoradiotherapy (CCRT) for rectal cancer. This study aims to demonstrate that the timing of metformin is related to the tumor response on preoperative CCRT for rectal cancer. From January 2010 to December 2017, 232 patients who underwent curative resection after preoperative CCRT were reviewed. Patients were divided into groups with or without diabetes or metformin. The timing of metformin administration was divided based on before and from initiation of CCRT. Multivariate logistic regression analysis was used to identify predictors for tumor response. Tumor downstaging (p = 0.02) and good response rates of tumor regression grade (TRG) (p = 0.008) were significantly higher in the group administered metformin before CCRT than other groups. In the multivariate analysis, metformin administration before CCRT was a significant factor in predicting tumor downstaging [odds ratio (OR) 10.31, 95% confidence interval (CI) 1.76–102.08, p = 0.02] and good TRG (OR 12.55, 95% CI 2.38–80.24, p = 0.004). In patients with rectal cancer who underwent preoperative CCRT, neoadjuvant therapy of metformin before CCRT was significantly associated with good tumor response.

Current regular aspirin use and mammographic breast density: a cross-sectional analysis considering concurrent statin and metformin use

PURPOSE

The nonsteroidal anti-inflammatory drug aspirin is an agent of interest for breast cancer prevention. However, it is unclear if aspirin affects mammographic breast density (MBD), a marker of elevated breast cancer risk, particularly in the context of concurrent use of medications indicated for common cardiometabolic conditions, which may also be associated with MBD.

METHODS

We used data from the New York Mammographic Density Study for 770 women age 40-60 years old with no history of breast cancer. We evaluated the association between current regular aspirin use and MBD, using linear regression for continuous measures of absolute and percent dense areas and absolute non-dense area, adjusted for body mass index (BMI), sociodemographic and reproductive factors, and use of statins and metformin. We assessed effect modification by BMI and reproductive factors.

RESULTS

After adjustment for co-medication, current regular aspirin use was only positively associated with non-dense area (β = 18.1, 95% CI: 6.7, 29.5). Effect modification by BMI and parity showed current aspirin use to only be associated with larger non-dense area among women with a BMI ≥ 30 (β = 28.2, 95% CI: 10.8, 45.7), and with lower percent density among parous women (β = -3.3, 95% CI: -6.4, -0.3).

CONCLUSIONS

Independent of co-medication use, current regular aspirin users had greater non-dense area with stronger estimates for women with higher BMI. We found limited support for an association between current aspirin use and mammographically dense breast tissue among parous women.

Meta-analysis of aspirin-guided therapy of colorectal cancer

Abstract

Purpose colorectal cancer (CRC) is one of the most commonly diagnosed cancers worldwide. Some evidence has shown that aspirin can reduce the morbidity and mortality of CRC. The aim of this meta-analysis was to compare standard care of patients with CRC and standard care with the addition of aspirin in terms of the survival benefit.

Methods

The systematic search was conducted by two independent reviewers in the databases PubMed and Web of Science. Survival data were extracted from studies published before July 2019. We searched for randomised controlled trials, cohort studies and case-control studies.

Results

We included 27 studies in our meta-analysis. There was a sample size of 237,245 patients overall. Aspirin use after diagnosis was associated with an improvement in CRC-specific survival with a hazard ratio (HR) for cancer-related death of 0.74 (95% CI: 0.62–0.89). Our analysis of overall survival data revealed reduced mortality with an HR of 0.82 (95% CI: 0.74–0.90). Patients with the phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) mutation profited from postdiagnosis aspirin use (HR = 0.74, 95% CI: 0.56–0.97). For a high expression of prostaglandin-endoperoxide synthase 2 (PTGS2) = COX-2, we found an HR of 0.65 (95% CI: 0.52–0.82).

Conclusion

Aspirin can improve the outcome of patients with CRC. PIK3CA mutation status and high expression of PTGS2 are associated with longer survival. However, randomised controlled trials are needed to investigate postdiagnosis aspirin use in CRC patients taking into account cancer stage and gene expression.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-022-03942-1.

Colorectal Cancer Survivors' Receptivity toward Genomic Testing and Targeted Use of Non-Steroidal Anti-Inflammatory Drugs to Prevent Cancer Recurrence

Genomic testing and targeted use of non-steroidal anti-inflammatory drugs (NSAIDs) may mitigate cancer recurrence risks. This study examines colorectal cancer (CRC) survivors' interest and receptivity to these strategies. Patients diagnosed with stage I-III CRC in 2004-2012 were recruited through the New Mexico Cancer Registry to complete a cancer survivorship experiences survey. We assessed interest in genomic testing, daily aspirin (ASA) and NSAID use, and receptivity to future daily ASA/NSAIDs. Descriptive statistics and multivariable logistic regression models estimated factors associated with genomic testing interest. Receptivity to future ASA/NSAIDs use was estimated for non-users of ASA/NSAIDs. Among CRC survivors (n = 273), 83% endorsed interest in genomic testing, 25% were ASA users and 47% ASA/NSAIDs users. In our final model, genomic testing interest was associated with being uncoupled [OR = 4.11; 95% CI = 1.49-11.35], low income [OR = 0.35, 95% CI: 0.14-0.88], smoking history [OR = 0.35, 95% CI: 0.14-0.90], low [OR: 0.33, 95% CI: 0.07-1.43] and moderate [OR: 0.26, 95% CI: 0.11-0.61] health literacy, and personal CRC risk worry [OR: 2.86, 95% CI: 1.63-5.02, p = 0.0002]. In our final model, ASA use was associated with age [OR: 1.05, 95% CI: 1.01-1.10] and cardiovascular disease history [OR: 2.42, 95% CI: 1.23-4.73, p = 0.010]. Among non-users ASA/NSAIDs, 83% reported receptivity to ASA/NSAIDs to reduce cancer risks, and no significant correlates were identified. The majority of survivors' expressed genomic testing interest and endorsed receptivity toward ASA/NSAIDs use for cancer risk management. Further research to optimize ASA/NSAIDs use guided by genomic testing is warranted.

The Association of Metformin, Other Antidiabetic Medications, and Statins With the Prognosis of Colon Cancer in Patients With Type 2 Diabetes: A Retrospective Cohort Study

BACKGROUND

Use of metformin and statins have been associated with improved prognosis of colon cancer (CC) in patients with type 2 diabetes (T2D). We examined the survival from CC in relation to the use of metformin, other oral antidiabetic medications (ADM), insulin, and statins in T2D patients.

MATERIALS AND METHODS

A cohort (n = 2252) of persons with pre-existing T2D diagnosed with incident CC between 1998 and 2011 was identified from several Finnish registers. Cox models were fitted for cause-specific mortality rates to obtain adjusted estimates of the hazard ratios (HR) with 95% confidence intervals (CI) in relation to use of ADM and statins before the CC diagnosis. Cox models were also fitted for mortality in relation to post-diagnostic use of the medications treating these as time-dependent exposures, and starting follow-up 1 year after the CC diagnosis.

RESULTS

Pre- and post-diagnostic metformin use was weakly associated with the risk of CC-related death (HR .75; 95% CI .58-.99, and HR .78; 95% CI .54-1.14, respectively) compared to the use of other oral ADMs. Pre- and post-diagnostic statin use predicted a reduced risk of CC-related death (HR .83; 95% CI .71- .98, and HR .69; 95% CI .54-.89, respectively).

CONCLUSION

Additional evidence was found for use of statins being associated with an improved survival from CC in patients with pre-existing T2D, but for metformin use the evidence was weaker.

Effect of metformin use on the risk and prognosis of colorectal cancer in diabetes mellitus: a meta-analysis

BACKGROUND

Whether metformin is a protective factor of colorectal cancer (CRC) among CRC patients is still not entirely clear. Thus, we conducted this systemic review and meta-analysis to provide a comprehensive review of associations between metformin therapy and CRC risk or survival outcomes for clinical decisions.

METHODS

Articles published before July 2021 were searched in databases (PubMed and Web of Science). Odds ratio (OR)/risk ratio (RR) or hazard ratio (HR) and their confidence intervals (CIs) were computed using STATA 12.0 software. Q test and I2 were conducted to explore heterogeneities between studies.

RESULTS

The present meta-analysis showed that metformin use was associated with decreased risk and lower all-cause mortality of CRC in diabetes mellitus (DM) with random-effects models (risk: OR/RR = 0.71, 95% CI, 0.64-0.80, I2 = 89.3%, P < 0.001; all-cause mortality: HR = 0.72, 95% CI, 0.62-0.83, I2 = 60.1%, P = 0.014). In addition, the study showed that metformin use was associated with a lower CRC-specific mortality in DM in cohort studies with a fixed-effects model (HR = 0.80, 95% CI, 0.70-0.92, I2 = 34.7%, P = 0.190).

CONCLUSION

Overall, in this meta-analysis, we found that metformin may be a protective factor for CRC risk and prognosis in patients with DM. Further well-designed, large-scale clinical studies are needed to evaluate the accuracy of our findings and more preclinical experiments are needed to reveal the underlying mechanism of metformin.

Timing of Aspirin Use Among Patients With Colorectal Cancer in Relation to Mortality: A Systematic Review and Meta-Analysis

Background

Exposure of aspirin has been associated with reduced risk of colorectal cancer (CRC) incidence, but aspirin use in relation to CRC patients' mortality remains undetermined. It is necessary to quantify the association between aspirin use and CRC mortality.

Methods

Two authors independently searched the electronic databases (PubMed, Embase, and the Cochrane Library) from 1947 through April 25, 2020. All observational studies assessing the association between different timing of aspirin use and CRC mortality were included. The effect size on study outcomes was calculated using random-effect model and presented as risk ratio (RR) with 95% confidence interval (CI). Heterogeneity, publication bias, and quality of included studies were also assessed.

Results

A total of 34 studies were included in this systematic review and meta-analysis. Prediagnosis aspirin use was not associated with CRC-specific mortality (RR = 0.91, 95% CI = 0.79 to 1.05) and all-cause mortality (RR = 0.87, 95% CI = 0.57 to 1.31). A statistically significant association between continued aspirin use and improvement in both CRC-specific mortality (RR = 0.76, 95% CI = 0.70 to 0.81) and all-cause mortality (RR = 0.83, 95% CI = 0.74 to 0.93) was observed. Postdiagnosis use of aspirin was associated only with reduced all-cause mortality (RR = 0.80, 95% CI = 0.69 to 0.94).

Conclusions

Continued aspirin use before and after CRC diagnosis has the most advantage regarding the improvement of CRC mortality. Nevertheless, further prospective trials and mechanistic studies are highly warranted.

Is Metformin Associated With Improved Response to Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer?

Efforts to determine whether metformin can increase the effectiveness of neoadjuvant chemoradiotherapy in rectal cancer have increased in recent years. However, retrospective studies have yielded inconclusive results.

OBJECTIVES

The aim of this study was to compare oncological outcomes and survival after neoadjuvant chemoradiotherapy in patients with rectal cancer taking metformin versus in those not taking metformin.

METHODS

This study analyzed 423 consecutive patients with locally advanced rectal cancer who underwent neoadjuvant chemoradiotherapy and curative surgery between January 2010 and May 2020; of these, 59 were taking metformin and 364 were not taking metformin.

RESULTS

Patients taking metformin had a lower proportion of tumor regression (6.8% versus 22.0%, P = 0.012) as well as a lower proportion of patients achieving a pathological complete response (6.8% versus 20.6%, P = 0.011). In the multivariate analysis, independent predictors of pathologic complete response were not taking metformin (OR: 5.26, 95% CI: 1.12-24.85, P= 0.035) and cT2 stage (OR: 3.49, 95% CI: 1.10-11.07, P= 0.034); the interval was also an independent predictor of tumor regression (OR: 1.78, 95% CI: 1.06-2.96, P= 0.028). No differences were observed in survival between groups.

CONCLUSION

Metformin was not associated with better tumor responses or survival after neoadjuvant treatment.

Population-wide impacts of aspirin, statins, and metformin use on prostate cancer incidence and mortality

We evaluated the association between aspirin, statins, and metformin use and prostate cancer (PC) incidence and mortality using a large population-based dataset. 388,760 men who participated in national health screening program in Korea during 2002–2003 were observed from 2004 to 2013. Hazard ratios of aspirin, statins, and metformin use for PC incidence and PC mortality were calculated with adjustment for simultaneous drug use. Cumulative use of each drug was inserted as time-dependent variable with 2-year time windows. Aspirin use ≥ 1.5 year (per 2-year) was associated with borderline decrease in PC mortality when compared to non-users (adjusted hazard ratio [aHR] 0.71, 95% confidence interval [CI] 0.50–1.02). Statins use was not associated with either PC incidence or PC mortality. Metformin ever-use was associated with decreased PC incidence compared with non-diabetics (aHR 0.86, 95% CI 0.77–0.96). Diabetics who were not using metformin or using low cumulative doses had higher PC mortality than non-diabetics (aHR 2.01, 95% CI 1.44–2.81, and aHR 1.70, 95% CI 1.07–2.69, respectively). However, subjects with higher cumulative doses of metformin did not show increased PC mortality. In conclusion, metformin use was associated with lower PC incidence. Use of aspirin and that of metformin among diabetic patients were associated with lower PC mortality.

Positive effect of metformin treatment in colorectal cancer patients with type 2 diabetes: national cohort study

We aimed to estimate colorectal cancer risk in patients with type 2 diabetes mellitus (T2DM) using metformin. Patients with colorectal cancer and diabetes from 2000 to 2012 were identified form Lithuanian Cancer Registry and the National Health Insurance Fund database. Standardized incidence ratios (SIRs) for colorectal cancers as a ratio of observed number of cancer cases in people with diabetes to the expected number of cancer cases in the underlying general population was calculated. We analysed 111 109 patients with diabetes. Overall, 1213 colorectal cancers were observed versus 954.91 expected within a period of observation entailing an SIR of 1.27 [95% confidence interval (CI): 1.20-1.34]. Significantly higher risk of colorectal cancer was found both in male and female patients with diabetes in all age groups. Higher risk was found for both colon and rectum cancers 1.36 (95% CI: 1.27-1.46) and 1.11 (95% CI: 1.01-1.22), respectively. There were no differences in risk over time since initial diabetes diagnosis. Never-users of metformin had twice higher risk of colorectal cancer compared to general population (SIR: 2.14, 95% CI: 1.95-2.35). Among metformin users, risk was lover (SIR: 1.47, 95% CI: 1.36-1.58) and colorectal cancer risk decreased with increasing cumulative dose of metformin (P < 0.001). Patients with T2DM had increased risk of colorectal cancer compared with the general Lithuanian population. Decreasing colorectal cancer risk with increasing cumulative dose of metformin indicates that metformin may be a protective agent for colorectal cancer development.

Aspirin and cancer survival: a systematic review and meta-analyses of 118 observational studies of aspirin and 18 cancers

BACKGROUND

Despite the accumulation of research papers on aspirin and cancer, there is doubt as to whether or not aspirin is an acceptable and effective adjunct treatment of cancer. The results of several randomised trials are awaited, and these should give clear evidence on three common cancers: colon, breast and prostate. The biological effects of aspirin appear likely however to be of relevance to cancer generally, and to metastatic spread, rather than just to one or a few cancers, and there is already a lot of evidence, mainly from observational studies, on the association between aspirin and survival in a wide range of cancers.

AIMS

In order to test the hypothesis that aspirin taking is associated with an increase in the survival of patients with cancer, we conducted a series of systematic literature searches to identify clinical studies of patients with cancer, some of whom took aspirin after having received a diagnosis of cancer.

RESULTS

Three literature searches identified 118 published observational studies in patients with 18 different cancers. Eighty-one studies report on aspirin and cancer mortality and 63 studies report on all-cause mortality. Within a total of about a quarter of a million patients with cancer who reported taking aspirin, representing 20%-25% of the total cohort, we found aspirin to be associated with a reduction of about 20% in cancer deaths (pooled hazard ratio (HR): 0.79; 95% confidence intervals: 0.73, 0.84 in 70 reports and a pooled odds ratio (OR): 0.67; 0.45, 1.00 in 11 reports) with similar reductions in all-cause mortality (HR: 0.80; 0.74, 0.86 in 56 studies and OR: 0.57; 0.36, 0.89 in seven studies). The relative safety of aspirin taking was examined in the studies and the corresponding author of every paper was written to asking for additional information on bleeding. As expected, the frequency of bleeding increased in the patients taking aspirin, but fatal bleeding was rare and no author reported a significant excess in fatal bleeds associated with aspirin. No author mentioned cerebral bleeding in the patients they had followed.

CONCLUSIONS

There is a considerable body of evidence suggestive of about a 20% reduction in mortality in patients with cancer who take aspirin, and the benefit appears not to be restricted to one or a few cancers. Aspirin, therefore, appears to deserve serious consideration as an adjuvant treatment of cancer, and patients with cancer, and their carers, have a right to be informed of the available evidence.

Metformin and cancer-specific survival among breast, colorectal, or endometrial cancer patients: A nationwide data linkage study

AIMS

Equivocal results of association between metformin and cancer-specific survival need more investigation. We tested the hypothesis that adherence to the drug had a lower cancer-specific mortality in a homogeneous population (i.e. regular users).

METHODS

The Australian Cancer database was linked to the Pharmaceutical Benefits Scheme data and the National Death Index. Adherence to metformin was calculated by proportion of days covered. Cox regression models with time-varying covariates were used to estimate multivariable-adjusted cause-specific hazard ratios (HRs) and 95% confidence intervals (CI) for the association of adherence to metformin and cancer-specific mortality.

RESULTS

Between 2003 and 2013, three separate cohorts of 6717, 3121, and 1854 female patients were identified with newly diagnosed breast, colorectal, or endometrial cancer. The 1-year adherence was similar at baseline in three cohorts, on average 75%. Each 10% increase in 1-year adherence to metformin reduced cancer-specific mortality among women with breast cancer (adjusted HR = 0.95; 95% CI, 0.93-0.97), colorectal cancer (adjusted HR = 0.94; 95% CI, 0.91-0.96), or endometrial cancer (adjusted HR = 0.95; 95% CI, 0.90-0.99). The inverse associations remained unchanged in most subgroup analyses.

CONCLUSIONS

Among metformin users, adherence to this drug is inversely associated with reduced cancer-specific mortality. If confirmed, metformin could be considered as an adjuvant treatment.

Does adherence to lipid-lowering medications improve cancer survival? A nationwide study of breast and colorectal cancer, and melanoma

AIMS

Inconclusive findings of lipid-lowering medications (LLMs) on cancer survival benefit require more evidence. We tested the hypothesis that adherence to this drug is associated with reduced cancer-specific mortality in a homogeneous population who had used this drug before cancer diagnosis.

METHODS

The Australian Cancer Database was linked to the Pharmaceutical Benefits Scheme database, and to the National Death Index (up to 2015). Medication adherence was calculated by proportion of days covered. Cox regression models with time-varying covariates were used to derive multivariable-adjusted cause-specific hazard ratio (HR) and 95% confidence interval (CI) for the associations between adherence to LLMs, statins, lipophilic, and hydrophilic statins and cancer-specific mortality.

RESULTS

From 2003 to 2013, 3 separate cohorts of 20 046, 11 719 and 6430 female patients with newly diagnosed breast, colorectal cancer, and melanoma respectively were identified. The 1-year adherence was similar at 1-year prediagnosis in the 3 cohorts, on average 82%. Each 10% increase in 1-year adherence to LLMs was inversely associated with cancer-specific mortality among women with breast cancer (fully adjusted HR = 0.92, 95% CI 0.91-0.93), colorectal cancer (fully adjusted HR = 0.92, 95% CI 0.91-0.93), or melanoma (fully adjusted HR = 0.97, 95% CI 0.94-1.00). The reductions in cancer-specific mortality were more pronounced for women who adhered to lipophilic than hydrophilic statins in all 3 cancers albeit not statistically significant for melanoma.

CONCLUSION

Among LLM users, adherence to this drug is associated with a decrease in cancer-specific mortality. If confirmed, LLMs could be considered as an adjuvant cancer therapy to improve prognosis in cancer survivors.

Survival Benefit for Metformin Through Better Tumor Response by Neoadjuvant Concurrent Chemoradiotherapy in Rectal Cancer

BACKGROUND

Metformin may reduce cancer risk and mortality and improve radiotherapy responses in several malignancies.

OBJECTIVE

This study aimed to compare tumor responses and prognoses of metformin and nonmetformin groups of diabetic patients receiving neoadjuvant concurrent chemoradiotherapy for rectal cancer.

DESIGN

This is a retrospective study.

SETTING

This study was conducted at a single institution in the Republic of Korea.

PATIENTS

Between January 2000 and November 2017, 104 patients with rectal cancer who were taking diabetes medication and treated with neoadjuvant concurrent chemoradiotherapy followed by radical surgery were reviewed. Patients were divided into those taking (n = 62) and not taking metformin (n = 42). Tumor responses, survival, and other outcomes were analyzed.

MAIN OUTCOME MEASURES

Tumor response, rectal cancer-specific survival, and disease-free survival rates were measured.

RESULTS

Tumor regression grade (p = 0.002), pathological complete response (p = 0.037), and N downstaging (p < 0.001) after neoadjuvant concurrent chemoradiotherapy were significantly higher in the metformin group than in the nonmetformin group. In analysis of cancer-specific mortality, metformin use, differentiation (well, moderate vs poor), pathological Union for International Cancer Control stage (3 vs 1-2), ypN stage (1-2 vs 0), and N downstaging (HR, 0.256 (95% CI, 0.082-0.794), p = 0.018; HR, 0.147 (95% CI, 0.031-0.697), p = 0.016; HR, 3.693 (95% CI, 1.283-10.635), p = 0.015; HR, 3.181 (95% CI, 1.155-8.759), p = 0.025, and HR, 0.175 (95% CI, 0.040-0.769), p = 0.021) were significant factors related to mortality in diabetic patients with rectal cancer. In addition, in the multivariate analysis of cancer recurrence, the interaction between metformin use and lymph node downstaging was a significant predictive factor (HR, 0.222 (95% CI, 0.077-0.639); p = 0.005).

LIMITATIONS

This was a small retrospective study conducted at a single institution.

CONCLUSIONS

Metformin use was associated with better tumor responses and cancer-specific survival, as well as a lower risk of cancer recurrence, in patients with diabetes mellitus who had lymph node downstaging after neoadjuvant concurrent chemoradiotherapy in rectal cancer. See Video Abstract at http://links.lww.com/DCR/B185. BENEFICIO EN SUPERVIVENCIA CON METFORMINA A TRAVÉS DE UNA MEJOR RESPUESTA TUMORAL CON QUIMIORRADIOTERAPIA CONCURRENTE NEOADYUVANTE EN CÁNCER RECTAL: La metformina puede reducir el riesgo de cáncer y la mortalidad y mejorar las respuestas a la radioterapia en varios tumores malignos.Comparar las respuestas tumorales y los pronósticos de los grupos con metformina y sin metformina de pacientes diabéticos que reciben quimiorradioterapia concurrente neoadyuvante para cáncer de recto.Estudio retrospectivo.Institución única en la República de Corea.Se revisaron 104 pacientes entre enero de 2000 y noviembre de 2017, con cáncer rectal que tomaban medicamentos para diabetes y que fueron tratados con quimiorradioterapia concurrente neoadyuvante seguida de cirugía radical. Los pacientes se dividieron en aquellos que tomaban (n = 62) y los que no tomaban metformina (n = 42). Se analizaron las respuestas tumorales, la supervivencia y otros resultados.Se midieron las tasas de la respuesta tumoral, la supervivencia específica de cáncer rectal y de la supervivencia libre de enfermedad.El grado de regresión tumoral (p = 0.002), la remisión patológica completa (p = 0.037) y la reducción de la etapa N (p < 0.001) después de la quimiorradioterapia concurrente neoadyuvante fueron significativamente mayores en el grupo de metformina que en el grupo sin metformina. En el análisis de la mortalidad específica por cáncer, el uso de metformina, la diferenciación (bien, moderada vs pobre), el estadio patológico UICC (3 vs 1-2), el estadio ypN (1-2 vs 0) y la disminución de la etapa N (hazard ratios [intervalos de confianza 95%]: 0.256 [0.082-0.794], p = 0.018; 0.147 [0.031-0.697], p = 0.016; 3.693 [1.283-10.635], p = 0.015; 3.181 [1.155-8.759], p = 0.025 y 0.175 [0.040-0.769], p = 0.021, respectivamente) fueron factores significativos relacionados con la mortalidad en pacientes diabéticos con cáncer rectal. Adicionalmente, en el análisis multivariado de la recurrencia del cáncer, la interacción entre el uso de metformina y la disminución de la etapa ganglionar (N) fue un factor predictivo significativo (hazard ratios [intervalos de confianza del 95%]: 0.222 [0.077-0.639]; p = 0.005).Este fue un estudio retrospectivo pequeño realizado en un solo instituto.El uso de metformina se asoció con mejores respuestas tumorales y supervivencia específica de cáncer, así como un menor riesgo de recurrencia del cáncer, en pacientes con disminución de la etapa ganglionar (N) después de quimiorradioterapia concurrente neoadyuvante en pacientes con cáncer rectal y diabetes. Consulte Video Resumen en http://links.lww.com/DCR/B185. (Traducción-Dr. Jorge Silva Velazco).

Metformin selectively inhibits metastatic colorectal cancer with the KRAS mutation by intracellular accumulation through silencing MATE1

CRC patients with KRAS mutations are confronted with limited targeted therapeutic options. In this study, we have shown that the median survival time for KRAS-mutation mCRC patients with diabetes on metformin is 37.8 mo longer than those treated with other hypoglycemic drugs in combination with standard systemic therapy. Metformin is preferentially accumulated in KRAS-mutation CRC cells in both primary cell cultures and patient-derived xenografts. The promising therapeutic activity of metformin has a negative correlation with MATE1 expression, which is proven to eliminate metformin from CRC cells. These findings indicate that KRAS-mutation mCRC patients could benefit from metformin treatment, and somatic KRAS status or MATE1 expression should be recommended to predict the therapeutic response of metformin in CRC.

Metastatic colorectal cancer (mCRC) patients have poor overall survival despite using irinotecan- or oxaliplatin-based chemotherapy combined with anti-EGFR (epidermal growth factor receptor) drugs, especially those with the oncogene mutation of KRAS. Metformin has been reported as a potentially novel antitumor agent in many experiments, but its therapeutic activity is discrepant and controversial so far. Inspiringly, the median survival time for KRAS-mutation mCRC patients with diabetes on metformin is 37.8 mo longer than those treated with other hypoglycemic drugs in combination with standard systemic therapy. In contrast, metformin could not improve the survival of mCRC patients with wild-type KRAS. Interestingly, metformin is preferentially accumulated in KRAS-mutation mCRC cells, but not wild-type ones, in both primary cell cultures and patient-derived xenografts, which is in agreement with its tremendous effect in KRAS-mutation mCRC. Mechanistically, the mutated KRAS oncoprotein hypermethylates and silences the expression of multidrug and toxic compound extrusion 1 (MATE1), a specific pump that expels metformin from the tumor cells by up-regulating DNA methyltransferase 1 (DNMT1). Our findings provide evidence that KRAS-mutation mCRC patients benefit from metformin treatment and targeting MATE1 may provide a strategy to improve the anticancer response of metformin.

Effect of metformin on the mortality of colorectal cancer patients with T2DM: meta-analysis of sex differences

PURPOSE

To evaluate the effect of metformin as a treatment for the mortality of colorectal cancer (CRC) patients with type 2 diabetes mellitus (T2DM).

METHODS

We searched Medline, PubMed, EMBASE, Clinical Trials.gov (http://www.clinicaltrials.gov), and the Cochrane Collaboration Library from inception to November 2019. To analyze the relationship between metformin and the overall mortality, specific mortality, and sex differences in CRC patients with T2DM, hazard ratios (HRs) with 95% confidence intervals (CIs) were used. Egger's test and Begg's test were used to assess publication bias.

RESULTS

We included 8 cohort studies in our meta-analysis. CRC patients with T2DM treated with metformin had a lower overall mortality than CRC patients with T2DM who did not receive metformin (HR = 0.80, 95% CI 0.67-0.95). There was no significant difference in CRC-specific mortality between CRC patients with T2DM who used metformin and those who did not (HR = 0.84, 95% CI 0.65-1.08). However, females had a lower CRC-specific mortality among CRC patients with T2DM than males (HR = 0.63, 95% CI 0.41-0.97).

CONCLUSION

Metformin reduced the overall mortality of CRC patients with T2DM. Moreover, female CRC patients with T2DM using metformin had lower CRC-specific mortality than male CRC patients with T2DM.

Postdiagnostic metformin use and survival of patients with colorectal cancer: A Nationwide cohort study

Epidemiological evidence for the association between postdiagnostic metformin use and survival in patients with colorectal cancer (CRC) remains limited. Using the Taiwan Cancer Registry database, a cohort of 16,676 diabetic patients newly diagnosed with CRC from January 1, 2004 through December 31, 2014, followed until December 31, 2016, was identified. Postdiagnostic use of metformin (two or more prescriptions after CRC diagnosis) was defined as a time-dependent covariate with 6-month lag. Multivariate Cox regression model and stabilized inverse probability of treatment weighting (IPTW) were used to estimate adjusted effects of metformin on all-cause mortality and CRC-specific mortality during follow-up. A number of 11,438 (69%) received metformin after CRC diagnosis. Overall, 7,393 deaths, including 4,845 CRC-specific deaths, were observed during 64,322 person-years of follow-up. After adjustment for demographic and clinical covariates, metformin users had lower all-cause mortality than did nonusers (hazard ratio [HR], 0.42; 95% confidence interval [CI], 0.40-0.44) and lower CRC-specific mortality (HR, 0.41; 95% CI, 0.39-0.44). Similar but somewhat attenuated effects were observed after stabilized IPTW (HR for all-cause mortality, 0.56; 95% CI, 0.53-0.59; HR for CRC-specific mortality, 0.58; 95% CI, 0.55-0.61). Similar results were observed in stratified analyses of 2,112 patients with no prediagnostic metformin use and 14,564 patients with prediagnostic metformin use. Findings for both outcomes were consistent in multiple sensitivity analyses. Use of postdiagnostic metformin was associated with significantly lower all-cause mortality and CRC-specific mortality, regardless of prior metformin use. These findings support the use of metformin as an adjunct to standard care of diabetic patients with CRC.

For colorectal cancer patients with type II diabetes, could metformin improve the survival rate? A meta-analysis

OBJECTIVE

Current research is controversial about whether metformin can improve the survival rate of patients with colon cancer. Therefore, we conducted a meta-analysis to identify the association between metformin and the survival rate of colorectal cancer (CRC) patients with type II diabetes.

METHODS

We conducted a search in databases including Pubmed, EMBASE and Cochrane Library. All articles were published in the last decade, and the quality of each study was evaluated by the Newcastle-Ottawa Scale. Odds ratios (ORs) and its corresponding 95% confidence intervals (CIs) for each study were calculated and summary relative risk estimates with corresponding 95% CIs were generated using the random-effects model. Heterogeneity and publication bias were assessed.

RESULTS

Ten articles were included in this meta-analysis. The included articles were all cohort studies. In a pooled analysis of all studies, metformin using was associated with increased overall survival (OS) rate (OR, 0.54; 95% CI, 0.47 to 0.63) and cancer-specific survival (CS) rate (OR 0.59; 95% CI 0.43 to 0.82) of CRC patients with diabetes. We found that the effect of metformin is associated with geographical region through subgroup meta-analysis.

CONCLUSIONS

Metformin using was associated with an increased OS rate and CS rate of colorectal cancer.

Suppressive effects of metformin on colorectal adenoma incidence and malignant progression

BACKGROUND

The linear progression from normal colonic epithelium to adenoma initiation, carcinoma transformation and metastasis is considered the classical model of colorectal cancer (CRC) development. Although metformin has been extensively reported to be negatively related to cancer incidence, the effect of metformin on CRC development remains unclear. We aimed to evaluate the role of metformin in the entire CRC linear progression.

METHODS

Systematic searches and data extraction were performed in the PubMed, Embase, and Cochrane Library databases on Jan 31, 2019. The combined relative ratios (RRs) of colorectal tumor incidence and the hazard ratios (HRs) of overall survival (OS) and cancer-specific survival (CSS) were evaluated by a random-effects model. Then, the effects of metformin were further assessed through stratified analyses by population, medication duration and dosage, dose-response analysis and comparison with other antidiabetic agents.

RESULTS

A total of 50 studies consisting of 238,540 cases of diabetes mellitus (DM) were included in this study. Metformin use was negatively associated with the incidence of colorectal adenoma (RR: 0.75, 95% CI: 0.65-0.86) and CRC (RR: 0.73, 95% CI: 0.58-0.90). Moreover, CRC patients benefited from metformin in terms of both OS (HR: 0.73, 95% Cl: 0.63-0.84) and CSS (HR: 0.60, 95% Cl: 0.50-0.73). Stratified analyses suggested that a long duration of high-dose metformin (RR: 0.52, 95% Cl: 0.36-0.83) was more effective than a short duration in Asian populations against colorectal adenoma (RR: 0.66, 95% Cl: 056-0.70) and CRC (RR: 0.45, 95% Cl: 0.29-0.70). Interestingly, metformin use decreased CRC risk in a dose-dependent manner (RR: 0.91, 95% CI: 0.87-0.95). In addition, the benefit of metformin on CRC was more significant than that of other antidiabetic agents, including insulin.

CONCLUSIONS

The use of metformin is associated with a lower incidence of adenoma and CRC and a better prognosis, especially in Asian populations.

Metformin increases cancer specific survival in colorectal cancer patients-National cohort study

PURPOSE

We aimed to assess oncological outcomes in colorectal cancer patients with type 2 diabetes mellitus (T2DM) using metformin.

METHODS

Patients with colorectal cancer and T2DM during 2000-2012 period were identified form Lithuanian Cancer Registry and the National Health Insurance Fund database. Colorectal cancer-specific survival (CS) was the primary outcome. It was measured from date of colorectal cancer diagnosis to date of death due to colorectal cancer, or last known date alive.

RESULTS

15,052 people who met eligibility criteria for this analysis, including 1094 (7.27%) with pre-existing type 2 diabetes (271 metformin never users and 823 metformin users) and 13 958 people without diabetes assessed. During follow-up (mean follow-up time was 4.4 years, with range from 1 day to 17 years) there were 10,927 deaths including 8559 from colorectal cancer. Significantly lower risk in CS between diabetic and non-diabetic people with lower risk of cancer-specific mortality (HR 0.87, 95% CI 0.80-0.94) in diabetic patient population was seen. After adjustment for age, stage at diagnosis and metformin usage, significant difference in colorectal CS between metformin users in diabetic patient population compared to non-diabetics and metformin non-users in diabetic patient population was found (0.80 (0.72-0.89) vs 1.00 and vs 1.05 (0.91-1.23)). Overall survival (OS) was better for diabetic patients with significant difference in diabetic metformin users (HR 0.91, 95% CI 0.79-0.94).

CONCLUSIONS

Colorectal cancer patients with T2DM treated with metformin as part of their diabetic therapy appear to have a superior OS and CS. However, prospective controlled studies are still needed to evaluate the efficacy of metformin as an anti-tumor agent.

Statin uses and mortality in colorectal cancer patients: An updated systematic review and meta-analysis

BACKGROUND

Colorectal cancer (CRC) remains one of the most common types of cancer and a leading cause of death worldwide. Previous studies indicated that statins may have a potential protective effect on CRC.

METHODS

We conducted this meta-analysis to systematically assess the overall and cancer-specific survival benefit of statin uses on CRC patients. Related references were identified through PubMed, the Cochrane Library, Web of Science, EMBASE, and SCOPUS from inception to August 2017. Adjusted hazard ratios (HRs) were adopted to calculate summary hazard ratios (HRs) with 95% confidence intervals (95% CIs), using a random-effects model.

RESULTS

Total fourteen studies involving 130 994 patients were included in this meta-analysis. Six studies reported the association between pre-diagnosis statin uses and CRC mortality, while 11 studies investigated mortality in patients using statins after CRC diagnosis. For pre-diagnosis statin uses, the pooled HR of all-cause mortality (ACM) was 0.85 (95% CI, 0.79-0.92) and the pooled HR of cancer-specific mortality (CSM) was 0.82 (95% CI, 0.79-0.86). In terms of post-diagnosis statin uses, the pooled HR of ACM was 0.86 (95% CI, 0.76-0.98), and the pooled HR of CSM was 0.79 (95% CI, 0.70-0.89). For post-diagnosis statin uses, there is no difference in ACM when stratified by KRAS gene (KRAS) mutation status. Results of ACM and CSM did not markedly alter in other subgroup analyses.

CONCLUSION

Our meta-analysis demonstrates that both pre-diagnosis and post-diagnosis statin uses are associated with reduced ACM and CSM for CRC patients.

Impact of Metformin Use and Diabetic Status During Adjuvant Fluoropyrimidine-Oxaliplatin Chemotherapy on the Outcome of Patients with Resected Colon Cancer: A TOSCA Study Subanalysis

BACKGROUND

Type 2 diabetes mellitus (T2DM) is associated with increased risk of colon cancer (CC), whereas metformin use seems to be protective. However, the impact of metformin use on the risk of death or disease recurrence after radical surgery for CC remains uncertain.

MATERIALS AND METHODS

This is a substudy conducted in patients with high-risk stage II or stage III CC randomized in the TOSCA trial, which compared 3 versus 6 months of fluoropyrimidine-oxaliplatin adjuvant chemotherapy. Objective of the study was to investigate the impact of metformin exposure during adjuvant chemotherapy on overall survival (OS) and relapse-free survival (RFS). We also evaluated the impact of T2DM or metformin dosage on clinical outcomes.

RESULTS

Out of 3,759 patients enrolled in the TOSCA trial, 133 patients with diabetes (9.2%) and 1,319 without diabetes (90.8%) were recruited in this study. After excluding 13 patients with diabetes without information on metformin exposure, 76 patients with T2DM (63.3%) were defined as metformin users and 44 (36.7%) as metformin nonusers. After a median follow-up of 60.4 months, 26 (21.7%) patients relapsed and 16 (13.3%) died. Metformin use was neither associated with OS (adjusted hazard ratio [HR], 1.51; 95% confidence interval [CI], 0.48-4.77; p = .4781) nor with RFS (HR, 1.56; 95% CI, 0.69-3.54; p = .2881). Similarly, we found no association between T2DM or metformin dosage and OS or RFS.

CONCLUSIONS

Metformin use and T2DM did not impact on OS or RFS in patients with resected CC treated with adjuvant fluoropyrimidine-oxaliplatin chemotherapy. Larger studies and longer follow-up are required to clarify the potential efficacy of metformin in improving the prognosis of patients with CC.

IMPLICATIONS FOR PRACTICE

The role of the antidiabetic drug metformin in colon cancer prevention and treatment is highly debated. While low-dose metformin reduced the incidence of colorectal adenomas in two prospective studies, its effect in patients with already established colon cancer remains unclear. In this study, the potential impact of metformin on the survival of resected colon cancer patients who received adjuvant chemotherapy was investigated in the context of the TOSCA study. We did not find any association between metformin use or dosages and patient survival. Prospective studies are required to draw definitive conclusions about metformin impact on colon cancer recurrence and survival.

Metformin and aspirin treatment could lead to an improved survival rate for Type 2 diabetic patients with stage II and III colorectal adenocarcinoma relative to non-diabetic patients

Metformin, the drug of choice in the treatment of type 2 diabetes mellitus (DM2), in addition to aspirin (ASA), the drug prescribed for cardioprotection of diabetic and non-diabetic patients, have an inhibitory effect on cancer cell survival. The present population-based study conducted in the province of Trieste (Italy), aimed to investigate the prevalence of DM2 in patients with colorectal adenocarcinoma (CRC) and survival for CRC in diabetic and nondiabetic patients. All permanent residents diagnosed with a CRC between 2004 and 2007 were ascertained through the regional health information system. CRC-specific and relative survival probabilities were computed for each group of patients defined by CRC stage, presence or absence of DM2 treated with metformin, and presence or absence of daily ASA therapy. A total of 515 CRC patients without DM2 and 156 with DM2 treated with metformin were enrolled in the study. At the time of CRC diagnosis, 71 (14%) nondiabetic and 39 (25%) diabetic patients were taking ASA daily. The five-year relative survival for stage III CRC was 101% [95% confidence interval (CI)=76-126] in the 18 patients with DM2 treated with metformin and ASA, 55% (95% CI=31-78) in the 23 without DM2 treated with ASA, 55% (95% CI=45-65) in the 150 without DM2 not taking ASA, and 29% (95% CI=13-45) in the 43 with DM2 treated with metformin, however not with ASA. The findings support the hypothesis of a possible inhibitory effect of metformin and ASA on CRC cells. Randomized controlled trials are required to verify this hypothesis.

The Effect of Metformin on Mortality Among Diabetic Cancer Patients: A Systematic Review and Meta-analysis

BACKGROUND

Most data suggest that cancer patients with diabetes have worse outcomes, which may be reversed with metformin. Metformin might modulate the clinical outcomes of diabetic cancer patients. We performed a systematic review and meta-analysis based on published studies over the past five years to summarize the effects of metformin on diabetic cancer patients.

METHODS

We systematically searched for studies that were published over the past five years. Then, we evaluated these studies for inclusion and extracted the relevant data. The summary risk estimates for the association between metformin treatment and all-cause mortality (ACM) and cancer-specific mortality (CSM) were analyzed using random or fixed-effects models. Stratified analyses by cancer site and country were also conducted.

RESULTS

Based on the 42 studies included in our analysis (37 015 diabetic cancer patients), we found a significant benefit associated with metformin treatment on survival corresponding to 27% and 26% reductions in ACM (hazard ratio [HR] = 0.73, 95% confidence interval [CI] = 0.68 to 0.79, P < .001) and CSM (HR = 0.74, 95% CI = 0.64 to 0.86, P < .001), respectively. The ACM rates for colorectal cancer, endometrial cancer, breast cancer, prostate cancer, and ovarian cancer showed significant benefits associated with metformin treatment in our stratified analyses by cancer site. Stratified analyses by cancer site also showed a significant reduction in CSM for breast cancer. This association between metformin treatment and reduced CSM for diabetic breast cancer patients was also observed in our country subgroup analyses.

CONCLUSIONS

We found an association between metformin exposure and reduced ACM and CSM in diabetic patients with cancer. Our findings suggest that metformin treatment could be an effective treatment option for diabetic cancer patients.

The association between metformin use and colorectal cancer survival among patients with diabetes mellitus: An updated meta-analysis

OBJECTIVE

Recent studies have reported conflicting results on the correlation between metformin use and outcomes in patients with colorectal cancer (CRC). A meta-analysis was performed to evaluate the efficacy of metformin therapy on the prognosis of CRC patients with type 2 diabetes mellitus (T2DM).

METHODS

We conducted a systematic search of PubMed, EMBASE, the Cochrane Library, and the Web of Science for related articles up to August 2016. Two investigators independently identified and extracted information. Pooled risk estimates [hazard ratios (HRs)] and 95% confidence intervals (CIs) were calculated using fixed-effects models. The risk of publication bias was assessed by examining funnel plot asymmetry as well as Egger's test and Begg's test.

RESULTS

Of 81 articles identified, 8 retrospective cohort studies, representing 6098 cases of CRC patients with T2DM who used metformin and 4954 cases of CRC patients with T2DM who did not use metformin, were included in this meta-analysis. There was no significant heterogeneity and quality difference between studies. Metformin users had significantly improved overall survival (OS) (HR = 0.82, 95% CI: 0.77-0.87, P = 0.000). However, Metformin use cannot affect CRC-specific survival (HR = 0.84, 95% CI: 0.69-1.02, P = 0.079) compared to non-users.

CONCLUSION

This meta-analysis suggests that metformin use may improve survival among CRC patients with T2DM. However, prospective controlled studies are still needed to rigorously evaluate the efficacy of metformin as an anti-tumor agent.

Epithelial-Mesenchymal Transition Phenotype, Metformin, and Survival for Colorectal Cancer Patients with Diabetes Mellitus II

OBJECTIVES

We aimed to explore the association between metformin treatment and epithelial-mesenchymal transition (EMT) phenotype and further appraise the prognostic values of metformin and EMT markers E-cadherin and vimentin for colorectal cancer (CRC) in clinical practice.

METHODS

We collected specimens and evaluated clinicopathological parameters of 102 stage I to III CRC patients with prediagnosed type 2 diabetes mellitus (DM II). Expression of E-cadherin and vimentin in tumors was detected by immunohistochemistry (IHC), and statistical analysis was performed using SPSS 19.0.

RESULTS

In correlation tests, we found a lower tumor cell EMT degree (more E-cadherin (P = 0.014) and less vimentin (P = 0.011) expression in patients who used metformin, and the expression of E-cadherin and vimentin was associated with serum CA19-9 (P = 0.048, P = 0.009), tumor invasive depth (T) (P < 0.001, P = 0.045), and lymph invasion (N) (P = 0.013, P = 0.001). In Cox multivariate regression analysis, E-cadherin was identified as a prognostic factor for disease-free survival (DFS) (P = 0.038) and metformin use (P = 0.015P = 0.044) and lymph invasion (P = 0.016P = 0.023) were considered as the prognostic factors for both DFS and overall survival (OS).

CONCLUSION

Our study suggested that metformin may impede the EMT process and improve survival for stage I-III CRC patients with DM II.

Statin treatment is associated with survival in a nationally representative population of elderly women with epithelial ovarian cancer

OBJECTIVE

Observational studies suggest that statin therapy for cardio-protection is associated with improved survival in cancer patients. We sought to evaluate the impact of statin treatment on ovarian cancer survival in a nationally representative elderly population.

METHODS

The linked Surveillance, Epidemiology, and End Results (SEER) registries and Medicare claims data on patients diagnosed with epithelial ovarian cancer in 2007-2009 were used to extract data on statin prescription fills, population characteristics, primary treatment, comorbidity and survival. Cox regression models were used to examine the association between statin treatment and overall survival.

RESULTS

Among the 1431 ovarian cancer patients who underwent surgical resection, 609 (42.6%) filled prescriptions for statin. The majority of statin-users (89%) were prescribed a lipophilic formulation. Mean overall survival among statin-users was 32.3months compared to 28.8months for non-users (p<0.0001). A 34% reduction in death was associated with statin therapy, independent of age, race, neighborhood median household income, stage, platinum therapy and comorbid conditions (HR=0.66, 95% CI 0.55-0.81). Improved overall survival with statin use was observed for both serous (HR=0.69, 95% CI 0.54-0.87) and non-serous (HR=0.63, 95% CI 0.44-0.90) histologies. When statin treatment was categorized by lipophilicity and intensity, a significant survival benefit was limited to lipophilic statin users and those who took statins of moderate intensity.

CONCLUSIONS

This SEER-Medicare analysis demonstrates improvement in overall survival with lipophilic statin use after surgery in elderly patients with epithelial ovarian cancer. A clinical trial to evaluate the impact of statin treatment in ovarian cancer survival is warranted.

Statin use, candidate mevalonate pathway biomarkers, and colon cancer survival in a population-based cohort study

BACKGROUND

Statin use after colorectal cancer diagnosis may improve survival but evidence from observational studies is conflicting. The anti-cancer effect of statins may be restricted to certain molecular subgroups. In this population-based cohort study, the interaction between p53 and 3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMGCR) expression, KRAS mutations, and the association between statin use and colon cancer survival was assessed.

METHODS

The cohort consisted of 740 stage II and III colon cancer patients diagnosed between 2004 and 2008. Statin use was determined through clinical note review. Tissue blocks were retrieved to determine immunohistochemical expression of p53 and HMGCR in tissue microarrays and the presence of KRAS mutations in extracted DNA. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for colorectal cancer-specific and overall survival.

RESULTS

Statin use was not associated with improved cancer-specific survival in this cohort (HR=0.91, 95% CI 0.64-1.28). Statin use was also not associated with improved survival when the analyses were stratified by tumour p53 (wild-type HR=1.31, 95% CI 0.67-2.56 vs aberrant HR=0.80, 95% CI 0.52-1.24), HMGCR (HMGCR-high HR=0.69, 95% CI 0.40-1.18 vs HMGCR-low HR=1.10, 95% CI 0.66-1.84), and KRAS (wild-type HR=0.73, 95% CI 0.44-1.19 vs mutant HR=1.21, 95% CI 0.70-2.21) status.

CONCLUSIONS

Statin use was not associated with improved survival either independently or when stratified by potential mevalonate pathway biomarkers in this population-based cohort of colon cancer patients.

Prognostic role of metformin intake in diabetic patients with colorectal cancer: An updated qualitative evidence of cohort studies

Several observational studies have shown that metformin can modify the risk and survival of colorectal cancer (CRC) in patients with diabetes mellitus, although the magnitude of this relationship has not been determined. We conducted an updated systematic review and meta-analysis to analyze the association between metformin and CRC mortality and searched relevant databases up to July 2016. The primary outcome was overall survival (OS). Secondary outcomes were cancer-specific survival (CS) and disease-free survival (DFS). Summary hazard ratios (HRs) were calculated using a random-effects model. Seventeen studies enrolling 269,417 participants were eligible for inclusion. Comparing with non-metformin users in diabetic CRC patients, the summary HRs for OS in metformin users were 0.69 (95% CI, 0.61-0.77). Subgroup analyses stratified by the study characteristics and sensitivity analysis by the trim-and-fill method (adjusted HR 0.77, 95% CI, 0.67-0.87) confirmed the robustness of the results. However, significant OS benefit was noted in patients with stage II and III disease. Five studies reported the CRC prognosis for CS and three for DFS; metformin intake was significantly associated with patient CS (HR 0.75, 95% CI, 0.59-0.94), but not DFS (HR 0.38, 95% CI, 0.13-1.17). Our findings suggest that metformin intake is associated with improved survival outcomes in terms of OS and CS in CRC patients with diabetes, particular for OS in stage II and stage III patients. Further studies should be conducted to determine CRC survival between metformin use and patient specific clinical and molecular profiles.

The mortality reducing effect of aspirin in colorectal cancer patients: Interpreting the evidence

In 1971 the first study appeared that suggested a relationship between aspirin and cancer. Currently publications on the subject of aspirin and cancer are numerous, with both a beneficial effect of aspirin on cancer incidence and a beneficial effect on cancer survival. This review focusses on the relation between the use of aspirin and improved survival in colorectal cancer patients. Various study designs have been used, with the main part being observational studies and post hoc meta-analyses of cancer outcomes in cardiovascular prevention trials. The results of these studies are unambiguously pointing towards an effect of aspirin on colorectal cancer survival, and several randomised controlled trials are currently ongoing. Some clinicians feel that the current evidence is conclusive and that the time has come for aspirin to be prescribed as adjuvant therapy. However, until this review, not much attention has been paid to the specific types of bias associated with these studies. One of these biases is confounding by indication, because aspirin is indicated for patients as secondary prevention for cardiovascular disease. This review aims to provide perspective on these biases and provide tools for the interpretation of the current evidence. Albeit promising, the current evidence is not sufficient to already prescribe aspirin as adjuvant therapy for colorectal cancer.

Metformin Improves Overall Survival of Colorectal Cancer Patients with Diabetes: A Meta-Analysis

Introduction. Diabetic population has a higher risk of colorectal cancer (CRC) incidence and mortality than nondiabetics. The role of metformin in CRC prognosis is still controversial. The meta-analysis aims to investigate whether metformin improves the survival of diabetic CRC patients. Methods. PubMed, EMBASE, and Cochrane Library were searched till July 1, 2016. Cohort studies were included. All articles were evaluated by Newcastle-Ottawa Scale. Hazard Ratios (HRs) with 95% confidence intervals (CIs) for each study were calculated and pooled HRs with corresponding 95% CIs were generated using the random-effects model. Heterogeneity and publication bias were assessed. Results. We included seven cohort studies with a medium heterogeneity (I² = 56.1% and p = 0.033) in our meta-analysis. An improved overall survival (OS) for metformin users over nonusers among colorectal cancers with diabetes was noted (HR 0.75; 95% CI 0.65 to 0.87). However, metformin reveals no benefits for cancer-specific survival (HR 0.79, 95%, CI 0.58 to 1.08). Conclusions. Metformin prolongs the OS of diabetic CRC patients, but it does not affect the CRC-specific survival. Metformin may be a good choice in treating CRC patients with diabetes mellitus in clinical settings.

Statin use and survival in colorectal cancer: Results from a population-based cohort study and an updated systematic review and meta-analysis

BACKGROUND

The aim of this study was to investigate the association between statin use and survival in a population-based colorectal cancer (CRC) cohort and perform an updated meta-analysis to quantify the magnitude of any association.

METHODS

A cohort of 8391 patients with newly diagnosed Dukes' A-C CRC (2009-2012) was identified from the Scottish Cancer Registry. This cohort was linked to the Prescribing Information System and the National Records of Scotland Death Records (until January 2015) to identify 1064 colorectal cancer-specific deaths. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for cancer-specific mortality by statin use were calculated using time dependent Cox regression models. The systematic review included relevant studies published before January 2016. Meta-analysis techniques were used to derive combined HRs for associations between statin use and cancer-specific and overall mortality.

RESULTS

In the Scottish cohort, statin use before diagnosis (HR=0.84, 95% CI 0.75-0.94), but not after (HR=0.90, 95% CI 0.77-1.05), was associated with significantly improved cancer-specific mortality. The systematic review identified 15 relevant studies. In the meta-analysis, there was consistent (I2=0%,heterogeneity P=0.57) evidence of a reduction in cancer-specific mortality with statin use before diagnosis in 6 studies (n=86,622, pooled HR=0.82, 95% CI 0.79-0.86) but this association was less apparent and more heterogeneous (I2=67%,heterogeneity P=0.03) with statin use after diagnosis in 4 studies (n=19,152, pooled HR=0.84, 95% CI 0.68-1.04).

CONCLUSION

In a Scottish CRC cohort and updated meta-analysis there was some evidence that statin use was associated with improved survival. However, these associations were weak in magnitude and, particularly for post-diagnosis use, varied markedly between studies.

Metformin as an adjuvant treatment for cancer: a systematic review and meta-analysis

BACKGROUND

Metformin use has been associated with a reduced risk of developing cancer and an improvement in overall cancer survival rates in meta-analyses, but, to date, evidence to support the use of metformin as an adjuvant therapy in individual cancer types has not been presented.

PATIENTS AND METHODS

We systematically searched research databases, conference abstracts and trial registries for any studies reporting cancer outcomes for individual tumour types in metformin users compared with non-users, and extracted data on patients with early-stage cancer. Studies were assessed for design and quality, and a meta-analysis was conducted to quantify the adjuvant effect of metformin on recurrence-free survival (RFS), overall survival (OS) and cancer-specific survival (CSS), to inform future trial design.

RESULTS

Of 7670 articles screened, 27 eligible studies were identified comprising 24 178 participants, all enrolled in observational studies. In those with early-stage colorectal cancer, metformin use was associated with a significant benefit in all outcomes [RFS hazard ratio (HR) 0.63, 95% confidence interval (CI) 0.47-0.85; OS HR 0.69, CI 0.58-0.83; CSS HR 0.58, CI 0.39-0.86]. For men with early-stage prostate cancer, metformin was associated with significant, or borderline significant, benefits in all outcomes (RFS HR 0.83, CI 0.69-1.00; OS HR 0.82, CI 0.73-0.93; CSS HR 0.58, CI 0.37-0.93); however, there was significant heterogeneity between studies. The data suggest that prostate cancer patients treated with radical radiotherapy may benefit more from metformin (RFS HR 0.45, CI 0.29-0.70). In breast and urothelial cancer, no significant benefits were identified. Sufficient data were not available to conduct analyses on the impact of metformin dose and duration.

CONCLUSIONS

Our findings suggest that metformin could be a useful adjuvant agent, with the greatest benefits seen in colorectal and prostate cancer, particularly in those receiving radical radiotherapy, and randomised, controlled trials which investigate dose and duration, alongside efficacy, are advocated.

Synergistic Benefit of Statin and Metformin in Gastrointestinal Malignancies

OBJECTIVES

To evaluate whether statin use influences gastrointestinal cancer prognosis in patients with diabetes mellitus (DM).

METHODS

We reviewed all DM patients diagnosed at Roswell Park Cancer Institute with emergent gastrointestinal malignancy (January 2003 to December 2010) (N = 222). Baseline demographic, clinical history, and cancer outcomes were documented. Overall survival (OS) and disease-free survival (DFS) comparisons across various treatment groups were assessed by Kaplan-Meier and Cox proportional hazards.

RESULTS

Use of statin, alone or in combination, was associated with improved OS and DFS (hazard ratio [HR] = 0.65, P = .06; HR = 0.60, P < .02). We report similar OS and DFS advantage among users of mono- or combined metformin therapy (HR = 0.55, P < .01; HR = 0.63, P < .02). Concomitant use of metformin and statin provided a synergistic OS and DFS benefit (HR = 0.42, P < .01; HR = 0.44, P < .01). Despite significant tobacco and alcohol use history, patients with upper gastrointestinal cancers derived enhanced cancer outcomes from this combination (HR = 0.34, P < .01; HR = 0.43, P < .02), while receiving a statin without metformin or metformin without a statin did not provide significant cancer-related benefits.

CONCLUSION

Use of statin and metformin provides a synergistic improvement in gastrointestinal malignancies outcomes.

Aspirin in the Treatment of Cancer: Reductions in Metastatic Spread and in Mortality: A Systematic Review and Meta-Analyses of Published Studies

BACKGROUND

Low-dose aspirin has been shown to reduce the incidence of cancer, but its role in the treatment of cancer is uncertain.

OBJECTIVES

We conducted a systematic search of the scientific literature on aspirin taken by patients following a diagnosis of cancer, together with appropriate meta-analyses.

METHODS

Searches were completed in Medline and Embase in December 2015 using a pre-defined search strategy. References and abstracts of all the selected papers were scanned and expert colleagues were contacted for additional studies. Two reviewers applied pre-determined eligibility criteria (cross-sectional, cohort and controlled studies, and aspirin taken after a diagnosis of cancer), assessed study quality and extracted data on cancer cause-specific deaths, overall mortality and incidence of metastases. Random effects meta-analyses and planned sub-group analyses were completed separately for observational and experimental studies. Heterogeneity and publication bias were assessed in sensitivity analyses and appropriate omissions made. Papers were examined for any reference to bleeding and authors of the papers were contacted and questioned.

RESULTS

Five reports of randomised trials were identified, together with forty two observational studies: sixteen on colorectal cancer, ten on breast and ten on prostate cancer mortality. Pooling of eleven observational reports of the effect of aspirin on cause-specific mortality from colon cancer, after the omission of one report identified on the basis of sensitivity analyses, gave a hazard ratio (HR) of 0.76 (95% CI 0.66, 0.88) with reduced heterogeneity (P = 0.04). The cause specific mortality in five reports of patients with breast cancer showed significant heterogeneity (P<0.0005) but the omission of one outlying study reduced heterogeneity (P = 0.19) and led to an HR = 0.87 (95% CI 0.69, 1.09). Heterogeneity between nine studies of prostate cancer was significant, but again, the omission of one study led to acceptable homogeneity (P = 0.26) and an overall HR = 0.89 (95% CI 0.79-0.99). Six single studies of other cancers suggested reductions in cause specific mortality by aspirin, and in five the effect is statistically significant. There were no significant differences between the pooled HRs for the three main cancers and after the omission of three reports already identified in sensitivity analyses heterogeneity was removed and revealed an overall HR of 0.83 (95% CI 0.76-0.90). A mutation of PIK3CA was present in about 20% of patients, and appeared to explain most of the reduction in colon cancer mortality by aspirin. Data were not adequate to examine the importance of this or any other marker in the effect of aspirin in the other cancers. On bleeding attributable to aspirin two reports stated that there had been no side effect or bleeding attributable to aspirin. Authors on the other reports were written to and 21 replied stating that no data on bleeding were available.

CONCLUSIONS AND IMPLICATIONS

The study highlights the need for randomised trials of aspirin treatment in a variety of cancers. While these are awaited there is an urgent need for evidence from observational studies of aspirin and the less common cancers, and for more evidence of the relevance of possible bio-markers of the aspirin effect on a wide variety of cancers. In the meantime it is urged that patients in whom a cancer is diagnosed should be given details of this research, together with its limitations, to enable each to make an informed decision as to whether or not to take low-dose aspirin.

SYSTEMATIC REVIEW PROTOCOL NUMBER

CRD42015014145.

Repositioning of drugs for intervention in tumor progression and metastasis: Old drugs for new targets

The increasing unraveling of the molecular basis of cancer offers manifold novel options for intervention strategies. However, the discovery and development of new drugs for potential clinical applications is a tremendously time-consuming and costly process. Translating a novel lead candidate compound into an approved clinical drug takes often more than a decade, and the success rate is very low due to versatile efforts including defining its pharmacokinetics, pharmacodynamics, side effects as well as lack of sufficient efficacy. Thus, strategies are needed to minimize time and costs, while maximizing success rates. A very attractive strategy for novel cancer therapeutic options is the repositioning of already approved drugs. These medicines, approved for the treatment of non-malignant disorders, have already passed some early costs and time, have been tested in humans and are ready for clinical trials as anti-cancer drugs. Here we discuss the repositioning of nonsteroidal anti-inflammatory drugs (NSAID), statins, anti-psychotic drugs, anti-helminthic drugs and vitamin D as anti-tumor agents. We focus on their novel actions and potential for inhibition of cancer growth and metastasis by interfering with target molecules and pathways, which drive these malignant processes. Furthermore, important pre-clinical and clinical data are reviewed herein, which elucidate their therapeutic mechanisms which enable their repositioning for cancer therapy and disruption of metastasis.