Korean type 2 diabetes patients have multiple adenomatous polyps compared to non-diabetic controls

Metformin administration in prevention of colorectal polyps in type 2 diabetes mellitus patients

BACKGROUND

Colorectal polyps are frequently observed in patients with type 2 diabetes mellitus (DM), posing a significant risk for colorectal cancer. Metformin, a widely prescribed biguanidine drug for type 2 DM, has been suggested to have potential chemoprophylactic effects against various cancers.

AIM

To explore the correlation between colorectal polyps and metformin use in type 2 DM patients.

METHODS

Type 2 DM patients were categorized into polyp and non-polyp groups. Following this, all patients were categorized into the type 2 DM-metformin, type 2 DM-non-metformin, and non-type 2 DM groups. Based on the baseline colonoscopy results, we performed pairwise comparisons of the incidence of colorectal polyps among the three groups. Additionally, we analyzed the relationship between colorectal polyps and the duration of metformin use and between the size and number of polyps and metformin use. Simultaneously, we focused on the specific pathological types of polyps and analyzed their relationship with metformin use. Finally, we compared the incidence of polyps between metformin and non-metformin groups according to the interval colonoscopy results.

RESULTS

The rate of metformin use in patients with colorectal polyps was 0.502 times that of patients without colorectal polyps [odds ratio (OR) = 0.502, 95% confidence interval (CI): 0.365-0.689; P < 0.001]. The incidence of colorectal polyps did not differ significantly between the type 2 DM-metformin and non-type 2 DM groups (P > 0.05). Furthermore, the correlations between the duration of metformin use and the incidence of colorectal polyps and between the size and number of polyps and metformin use were not statistically significant (P > 0.05). Metformin use did not affect the incidence of colorectal polyps during interval colonoscopy (P > 0.05).

CONCLUSION

Metformin use and colorectal polyp incidence in type 2 DM patients showed a negative correlation, independent of the hypoglycemic effect of metformin.

Age-Specific Differences in the Risk of Colorectal Precursor Lesions Among Patients with Type 2 Diabetes Undergoing Surveillance Colonoscopy

BACKGROUND

The incidence rate of colorectal cancer (CRC) in young adults is rising in parallel with type 2 diabetes (T2D). The majority of CRC develop through two main subtypes of precursor lesions; adenomas and serrated lesions. The associations between age and T2D on development of precursor lesions remain uncertain.

OBJECTIVES

We studied the association of T2D with the development of adenomas and serrated lesions in individuals <50 versus ≥50 years of age, in a population undergoing long-term regular surveillance colonoscopy due to an elevated risk of CRC.

METHODS

A case-control study was conducted on patients who were enrolled in a surveillance colonoscopy program between 2010-2020. Findings at colonoscopy, clinical and demographic features were collected. Adjusted and unadjusted binary logistic regression assessed the association of age, T2D, sex, and other medical conditions and lifestyle-related factors with different subtypes of precursor lesions diagnosed at colonoscopy. Cox proportional hazards model analysis determined the association of T2D and other confounders with development time for precursor lesions.

RESULTS

Cases included 412 patients <50y [mean age 38.7 (range, 24-49y)] and 824 sex-matched controls ≥50y [62.1 (50-75y)]. Individuals <50y were less likely to have been diagnosed with T2D than those ≥50y (7% vs 22%, P-value<0.001). During the follow-up period, there was no significant association between T2D and diagnosis of any precursor lesions, but when considering development time, individuals with T2D developed non-significant adenomas earlier than those without T2D (HR =1.46; 95% CI: 1.14-1.87; P-value=0.003). However, this was not independent of age or findings at index colonoscopy.

CONCLUSIONS

T2D does not further increase the incidence of adenomas or serrated lesions in either a young or older cohort undergoing long-term surveillance colonoscopy.

Self-reported Metabolic Risk Factor Associations with Adenomatous, Sessile Serrated, and Synchronous Adenomatous and Sessile Serrated Polyps

Studies have found a positive association between metabolic risk factors, such as obesity and diabetes, and adenomatous polyps (AP). However, fewer studies have assessed the association between sessile serrated polyps (SSP) or synchronous diagnosis of APs and SSPs (synch polyps). Study participants (N = 1,370; ages 40-85) undergoing screening colonoscopy were enrolled between August 2016 and February 2020. Self-reported metabolic risk factors, including diabetes, hypertension, hyperlipidemia, and overweight/obesity, were evaluated for associations with new diagnoses of APs, SSPs, and synch polyps at the present colonoscopy. Average participant age was 60.73 ± 8.63 (SD) years; 56.7% were female and 90.9% white. In an assessment of individual metabolic risk factors, adjusted for age, sex, race, and smoking status, increased body mass index (BMI; overweight or obese vs. normal BMI of <25 kg/m2) was associated with an increased odds for new onset of colon APs (P trend < 0.001) as was a diagnosis of diabetes [adjusted conditional OR (aCOR) = 1.59 (1.10-2.29)]. No associations were seen between the metabolic risk factors and onset of SSPs. Being obese or hypertensive each increased the odds of new onset of synch polyps with aCOR values of 2.09 (1.01-4.32) and 1.79 (1.06-3.02), respectively. Self-reported risk factors may help assess polyp type risk. Because SSPs and synch polyps are rare, larger studies are needed to improve our understanding of the contribution of these factors to polyp risk. These data lead us to hypothesize that differences in observed metabolic risk factors between polyp types reflect select metabolic impact on pathways to colorectal cancer. PREVENTION RELEVANCE: Self-reported medical history provides valuable insight into polyp risk, potentially enabling the use of larger retrospective studies of colonoscopy populations to assess knowledge gaps. More aggressive colonoscopy screening, critical to colorectal cancer prevention, may be considered in populations of individuals with metabolic risk factors and modifiable lifestyle risk factors.

Diabetes and Cancer: Cancer Should Be Screened in Routine Diabetes Assessment

Cancer incidence appears to be increased in both type 1 and type 2 diabetes mellitus (DM). DM represents a risk factor for cancer, particularly hepatocellular, hepatobiliary, pancreas, breast, ovarian, endometrial, and gastrointestinal cancers. In addition, there is evidence showing that DM is associated with increased cancer mortality. Common risk factors such as age, obesity, physical inactivity and smoking may contribute to increased cancer risk in patients with DM. Although the mechanistic process that may link diabetes to cancer is not completely understood yet, biological mechanisms linking DM and cancer are hyperglycemia, hyperinsulinemia, increased bioactivity of insulin-like growth factor 1, oxidative stress, dysregulations of sex hormones, and chronic inflammation. However, cancer screening rate is significantly lower in people with DM than that in people without diabetes. Evidence from previous studies suggests that some medications used to treat DM are associated with either increased or reduced risk of cancer. However, there is no strong evidence supporting the association between the use of anti-hyperglycemic medication and specific cancer. In conclusion, all patients with DM should be undergo recommended age- and sex appropriate cancer screenings to promote primary prevention and early detection. Furthermore, cancer should be screened in routine diabetes assessment.

Synchronous colorectal carcinoma: predisposing factors and characteristics

AIM

Whether some diseases are related to the occurrence of synchronous colorectal carcinoma (sCRC) is unknown. Investigating the risk factors and presentation of sCRC could aid in the treatment of patients with colorectal cancer (CRC). The prognosis of sCRC compared with that of solitary CRC remains unclear.

METHODS

A total of 17 093 CRC patients were recruited between 1st January 1995 and 31th December 2016. The risk factors of sCRC development were assessed using univariate and multivariate logistic regression. The effect of sCRC on survival was analysed using the multivariate Cox regression model.

RESULTS

The prevalence of sCRC was 5.6% in this study. The independent risk factors of sCRC development were advanced age (P < 0.001), male sex (P < 0.001), hereditary cancer (P < 0.001), hypertension (P < 0.001) and liver cirrhosis (P = 0.024). Compared with solitary CRC, a higher number of patients with sCRC presented with an abnormal carcinoembryonic antigen (CEA) level (P = 0.011), anaemia (P < 0.001) and hypoalbuminemia (P < 0.001). Multivariate analysis revealed that sCRC was a significant factor for poor survival in patients at TNM Stage I [hazard ratio (HR) = 1.86; P < 0.001], Stage II (HR = 1.65; P < 0.001) and Stage III (HR = 1.40; P < 0.001).

CONCLUSIONS

In addition to hypertension and liver cirrhosis, other risk factors for sCRC were identified in this study. The prognosis of patients with sCRC was significantly worse than that of those with solitary CRC through TNM Stages I to III. Anaemia, abnormal CEA and hypoalbuminemia were more commonly seen in patients with sCRC.

Diabetes mellitus and hyperglycemia control on the risk of colorectal adenomatous polyps: a retrospective cohort study

Background

Colorectal cancer (CRC) develops from colorectal adenomatous polyps. This study is to determine if diabetes mellitus (DM), its treatment, and hemoglobin A1c (HbA1c) level are associated with increased risk of colorectal adenomatous polyps.

Methods

This was a retrospective cohort study that included patients who had at least one colonoscopy and were continuously enrolled in a single managed care organization during a 10-year period (2002–2012). Of these patients (N = 11,933), 1800 were randomly selected for chart review to examine the details of colonoscopy and pathology findings and to confirm the diagnosis of DM. Multivariable logistic regression analyses were performed to assess the associations between DM, its treatment, HbA1c level and adenomatous polyps (our main outcome).

Results

Among the total of 11,933 patients with a mean (standard deviation) age of 56 (± 8.8) years, 2306 (19.3%) had DM and 75 (0.6%) had CRC. Among the 1800 under chart review, 445 (24.7%) had DM, 11 (0.6%) had CRC and 537 (29.8%) had adenomatous polyps. In bivariate analysis, patients with DM had 1.45 odds of developing adenomatous polyps compared to those without DM. This effect was attenuated (odds ratio = 1.25, 95% CI: 0.96–1.62, p = 0.09) after adjusting for confounders such as age, gender, race/ethnicity, and body mass index. There was no significant association between type or duration of DM treatment or HbA1c level and adenomatous polyps.

Conclusions

Our study confirmed the known increased risk of adenomatous polyps with advancing age, male gender, Hispanic race/ethnicity and higher body mass index. Although it suggested an association between DM and adenomatous polyps, a statistically significant association was not observed after controlling for other potential confounders. Further studies with a larger sample size are needed to further elucidate this relationship.

Significantly higher rates of multiple and proximally located adenomas among patients with diabetes mellitus: A cross-sectional population-based study

BACKGROUND

Diabetes mellitus (DM) is associated with a greater risk for colorectal cancer (CRC).

OBJECTIVE

The objective of this article is to examine the endoscopic phenotype and histopathology of colorectal polyps in patients with vs without DM.

METHODS

We conducted a cross-sectional study of patients who underwent colonoscopy at our university hospital and who completed a questionnaire. We collected endoscopy and histopathology data regarding colorectal adenomas and serrated polyps. Cox regression analyses were used to estimate adjusted prevalence ratios (PRs).

RESULTS

We examined a total of 3654 patients (mean age (SD): 62 (12) years, 47% males). Of them, 360 (9.9%) had DM. Overall, the prevalence of colorectal adenomas (42% vs 32%, p < 0.01), multiple (≥3) adenomas (12% vs 7%, p = 0.01) and proximal adenomas (30% vs 19%, p < 0.01) was higher in patients with vs without DM. Multivariable analysis showed that the prevalence of adenomas (PR 1.17, 95% CI; 1.02-1.34), multiple (PR 1.37, 95% CI; 1.00-1.86) and proximal (PR 1.37, 95% CI; 1.16-1.62) adenomas was higher in patients with vs without DM, especially in men.

CONCLUSION

Patients with DM harbor more frequently multiple and proximal adenomas than those without DM. Close colonoscopic surveillance of DM patients is important to maximize the effectiveness of colonoscopic CRC prevention.

Diabetes Mellitus and Site-specific Colorectal Cancer Risk in Korea: A Case-control Study

Objectives:

Previous large-scale cohort studies conducted in Korea have found a positive association between diabetes mellitus (DM) and colorectal cancer (CRC) in men only, in contrast to studies of other populations that have found significant associations in both men and women.

Methods:

A total of 1070 CRC cases and 2775 controls were recruited from the National Cancer Center, Korea between August 2010 and June 2013. Self-reported DM history and the duration of DM were compared between cases and controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by binary and polytomous logistic regression models.

Results:

DM was associated with an elevated risk of CRC in both men (OR, 1.47; 95% CI, 1.13 to 1.90) and women (OR, 1.92; 95% CI, 1.24 to 2.98). This association remained when we controlled for age, body mass index, alcohol consumption, and physical activity level. In sub-site analyses, DM was associated with distal colon cancer risk in both men (multivariate OR, 2.04; 95% CI, 1.39 to 3.00) and women (multivariate ORs, 1.99; 95% CI, 1.05 to 3.79), while DM was only associated with rectal cancer risk in women (multivariate OR, 2.05; 95% CI, 1.10 to 3.82). No significant association was found between DM and proximal colon cancer risk in either men (multivariate OR, 1.45; 95% CI, 0.88 to 2.41) or women (multivariate OR, 1.79; 95% CI, 0.78 to 4.08).

Conclusions:

Overall, DM was associated with an increased risk of CRC in Koreans. However, potential over-estimation of the ORs should be considered due to potential biases from the case-control design.

Type 2 diabetes mellitus and risk of colorectal adenoma: a meta-analysis of observational studies

BACKGROUND

To summarize the relationship between type 2 diabetes mellitus (T2DM) and risk of colorectal adenomas (CRA), we performed a meta-analysis of observational studies.

METHODS

To find studies, we searched PubMed, Embase, the Cochrane Library, Web of Science and conference abstracts and related publications for American Society of Clinical Oncology and the European Society of Medical Oncology. Studies that reported relative risks (RRs) or odds ratios (ORs) with 95 % confidence intervals (CIs) for the association between T2DM and risk of CRA were included. The meta-analysis assessed the relationships between T2DM and risk of CRA. Sensitivity analyses were performed in two ways: (1) by omitting each study iteratively and (2) by keeping high-quality studies only. Publication bias was detected by Egger's and Begg's tests and corrected using the trim and fill method.

RESULTS

This meta-analysis included 17 studies with 28,999 participants and 6798 CRA cases. We found that T2DM was a risk factor for CRA (RR: 1.52; 95 % CI: 1.29-1.80), and also for the advanced adenoma (RR: 1.41; 95 % CI: 1.06-1.87). Patients with existing T2DM (RR: 1.56; 95 % CI: 1.16-2.08) or newly diagnosed T2DM (RR: 1.51; 95 % CI: 1.16-1.97) have a risk of CRA. Similar significant results were found in retrospective studies (RR: 1.57; 95 % CI: 1.30-1.89) and population based cross-sectional studies (RR: 1.46; 95 % CI: 1.21-1.89), but not in prospective studies (RR: 1.27; 95 % CI: 0.77-2.10).

CONCLUSIONS

Our results suggested that T2DM plays a risk role in the risk of developing CRA. Consequently, medical workers should increase the rate of CRA screening for T2DM patients so that they can benefit from behavioural interventions that can help prevent the development of colorectal cancer. Additional, large prospective cohort studies are needed to make a more convincing case for these associations.

Metformin and breast and gynecological cancer risk among women with diabetes

OBJECTIVE

We investigated if metformin lowers breast, endometrial, and ovarian cancer risk in women with type 2 diabetes mellitus compared with women who used other antidiabetic medications.

RESEARCH DESIGN AND METHODS

We followed a cohort of 66 778 female patients with diabetes for a maximum of 12 years (median 6 years). We examined breast, endometrial, and ovarian cancer risk, and the composite cancer risk. We examined drug categories using pharmacy records: metformin only; metformin combination regimens; non-metformin regimens; and non-users. We used χ(2) analyses to examine categorical variables. We conducted multivariable Cox regression models with time-dependent drug use status.

RESULTS

Women who used metformin combination regimens versus metformin only had a 15% lower breast cancer risk (adjusted HR=0.85, 95% CI 0.69 to 1.04). After stratifying by glycated hemoglobin (HbA1c), the association attenuated in those who had poorly controlled HbA1c (adjusted HR=1.06, 95% CI 0.73 to 1.55). Given the small numbers of ovarian and endometrial cancer outcomes, we examined these as a composite. The risk of all cancers combined was similar in those who used metformin combination regimens versus metformin only (adjusted HR=0.92, 95% CI 0.78 to 1.10). We found no significant differences for breast cancer or all cancers combined when we compared risks in non-metformin users versus metformin only users.

CONCLUSIONS

Women who used metformin and other antidiabetic drugs had a lower breast cancer risk compared with women who used metformin only, but the results were not significant. We also found no difference in overall cancer risks when we compared women who used other antidiabetic drugs (no metformin) versus metformin users.

The relationship between different glycemic statuses and colon polyps in a Taiwanese population

BACKGROUND

While diabetes is considered as a risk factor for colorectal cancer, there are few studies that address the association between glycemic statuses and different colon polyps, ranging from non-neoplastic polyps to advanced adenomatous polyps.

METHODS

A total of 6,348 participants, consisting of 3,777 men and 2,571 women, with a mean age of 50.5 years, were included for final analysis after excluding subjects with a past history of colorectal cancer, colon polyps/polypectomy, familial adenomatous polyposis, and colorectomy, or missing data. Diabetes and pre-diabetes were defined using the 2011 American Diabetes Association criteria. Subjects were classified into four groups: polyp-free, non-neoplastic polyps, non-advanced and advanced adenomatous polyps.

RESULTS

There were significant differences in the prevalence of diabetes and pre-diabetes among groups with different kinds of colon polyps. In addition, significant differences were also noted in age, total cholesterol, body mass index, triglyceride, high density lipoprotein-cholesterol, fasting plasma glucose, and the prevalence of male gender, hypertension, obesity, current smoking and alcohol drinking among groups. In the multinomial logistic regression analyses, diabetes was related to both non-advanced and advanced adenomatous polyps, while pre-diabetes was only related to non-advanced adenomatous polyps. In addition, age ≥65 years and male gender were associated with both non-advanced and advanced adenomatous polyps, while hypertension and current smoking were independently related to advanced and non-advanced adenomatous polyps, respectively.

CONCLUSIONS

Diabetes, but not pre-diabetes, was associated with a higher risk of advanced adenomatous polyps. In addition, both diabetes and pre-diabetes were important correlates of non-advanced adenomatous polyps.

Type 2 diabetes and the risk of colorectal adenomas: Black Women's Health Study

Evidence for the association of type 2 diabetes mellitus (DM) with colorectal neoplasms is contradictory, and African Americans have been underrepresented in the studies published to date. In a nested case-control study (1995-2009), we examined DM and insulin therapy as risk factors for colorectal adenomas in African American women enrolled in the ongoing Black Women's Health Study. From women reporting ever having undergone a gastrointestinal endoscopy, 917 cases of colorectal adenoma were compared with 2,751 controls without a colorectal polyp, matched on age and follow-up time. Cases were verified by medical record review. We used multivariable logistic regression analyses that included DM exposures and selected confounders. There were no overall associations between DM and adenoma risk or between insulin use and adenoma risk. However, DM without insulin use was inversely associated with risk of colon adenomas (odds ratio (OR) = 0.71, 95% confidence interval (CI): 0.52, 0.97) but not rectal adenomas. DM was inversely associated with adenoma risk in women older than 55 years (OR = 0.64, 95% CI: 0.44, 0.91) but not in women 55 years or younger (OR = 1.24, 95% CI: 0.81, 1.89). Future research should attempt to replicate the unexpected inverse association of DM with colon adenoma risk among older African American women.

Risk of colonic cancer is not higher in the obese Lep(ob) mouse model compared to lean littermates

Epidemiological data suggest that obesity increases the risk of colorectal cancer in humans. Given that diet-induced obesity mouse models verified the epidemiological data, the present study aimed to determine whether obese C57BL/6J-Lep(ob) male mice (a different obesity in vivo model) were at greater risk of colonic cancer than their lean male littermates. Risk of colonic tumorigenesis was assessed by numbers of aberrant crypts, aberrant crypt foci and colonic tumors. Proliferation of the colonic epithelia was assessed histochemically following administration of BrdU. Availability of the procarcinogen, azoxymethane (AOM) to target tissues was assessed by quantifying via HPLC plasma AOM concentrations during the 60 min period following AOM injection. When obese and lean mice were injected with azoxymethane (AOM) at doses calculated to provide equivalent AOM levels per kg lean body mass, obese animals had significantly fewer aberrant crypts/colon and fewer aberrant crypt foci/colon than the lean animals. Tumors were identified in the colonic mucosa of lean (4 tumors in 14 mice) but not obese (0 tumors in 15 mice) mice. Colonic cell proliferation was not significantly different for obese and lean mice. Because these results were unexpected, plasma AOM concentrations were measured and were found to be lower in the obese than lean mice. When plasma AOM levels were comparable for the lean and obese mice, the Lep(ob) mice continued to have significantly fewer aberrant crypt foci/colon than the lean mice, but differences were not statistically different for aberrant crypts/colon. Interestingly, obese Lep(ob) mice did not exhibit increased risk of colonic cancer as expected. Instead, Lep(ob) mice exhibited equivalent or lower risk of colon cancer when compared to the lean group. These results taken together with in vivo results from diet-induced obesity studies, imply that leptin may be responsible for the increased risk of colon cancer associated with obesity.

Metformin and the risk of cancer: time-related biases in observational studies

OBJECTIVE

Time-related biases in observational studies of drug effects have been described extensively in different therapeutic areas but less so in diabetes. Immortal time bias, time-window bias, and time-lag bias all tend to greatly exaggerate the benefits observed with a drug.

RESEARCH DESIGN AND METHODS

These time-related biases are described and shown to be prominent in observational studies that have associated metformin with impressive reductions in the incidence of and mortality from cancer. As a consequence, metformin received much attention as a potential anticancer agent; these observational studies sparked the conduction of randomized, controlled trials of metformin as cancer treatment. However, the spectacular effects reported in these studies are compatible with time-related biases.

RESULTS

We found that 13 observational studies suffered from immortal time bias; 9 studies had not considered time-window bias, whereas other studies did not consider inherent time-lagging issues when comparing the first-line treatment metformin with second- or third-line treatments. These studies, subject to time-related biases that are avoidable with proper study design and data analysis, led to illusory extraordinarily significant effects, with reductions in cancer risk with metformin ranging from 20 to 94%. Three studies that avoided these biases reported no effect of metformin use on cancer incidence.

CONCLUSIONS

Although observational studies are important to better understand the effects of drugs, their proper design and analysis is essential to avoid major time-related biases. With respect to metformin, the scientific evidence of its potential beneficial effects on cancer would need to be reassessed critically before embarking on further long and expensive trials.