The comparison of the clinical manifestations and risk factors of colorectal cancer and adenomas: results from a colonoscopy-based study in southern Chinese

Family History of Colorectal Cancer and the Risk of Colorectal Neoplasia: A Systematic Review and Meta-Analysis

INTRODUCTION

Although there is enough pooled evidence supporting the positive association between family history of colorectal cancer (CRC) in first-degree relatives (FDRs) and the risk of CRC, synthesized data on its association with the risk of other colorectal neoplasia are lacking. Therefore, we aimed to systematically assess this issue.

METHODS

We searched PubMed, Web of Science, and Embase from database inception through May 9, 2024, to identify observational studies investigating the association between family history of CRC in FDRs and the risk of colorectal neoplasia (excepting CRC). Adenoma, nonadvanced adenoma (NAA), advanced adenoma (AA), and advanced neoplasia (AN) were further chosen as main outcomes because of data availability. Random-effects model was used for data synthesis. Subgroup meta-analyses were performed to evaluate the robustness of results.

RESULTS

Of 5,172 initial records screened, 75 studies (with 931,515 participants) were identified for analysis. Family history of CRC in FDRs was associated with increased risk of adenoma (pooled odds ratio [OR] 1.67, 95% confidence interval [CI] 1.46-1.91), NAA (pooled OR 1.35, 95% CI 1.21-1.51), AA (pooled OR 1.66, 95% CI 1.46-1.88), and AN (pooled OR 1.58, 95% CI 1.44-1.73). The positive associations persisted in all examined subgroups. The risk of adenoma (pooled OR 4.18, 95% CI 1.76-9.91), AA (pooled OR 2.42, 95% CI 1.72-3.40), and AN (pooled OR 2.00, 95% CI 1.68-2.38) was more evident among individuals with 2 or more affected FDRs.

DISCUSSION

Family history of CRC is associated with increased risk of adenoma, NAA, AA, and AN totally, and in all available subgroups. The findings further strengthen the necessity and importance of an intensified screening strategy for individuals with a positive family history of CRC, which is very useful for related health resource allocation and policymaking.

No bidirectional relationship between constipation and colorectal cancer in European and Asian populations: A Mendelian randomization study

Traditional observational studies have reported a positive association between constipation and the risk of colorectal cancer (CRC). However, evidence from other approaches to pursue the causal relationship between constipation and CRC is scarce. In the study, 2-sample Mendelian randomization analysis was conducted to investigate the potential causal relationship between constipation and CRC. Analysis of the results showed that there was no causal association between constipation and CRC, either in European populations (CRC: odds ratio [OR] = 1.00, 95% confidence interval [CI] = 0.99-1.00, P = .49; rectal cancer: OR = 0.99, 95% CI = 0.99-1.00, P = .79) or in Asian populations (CRC: OR = 1.00, 95% CI = 0.99-1.01, P = .30). Also there was no inverse causal association between CRC and constipation, either in European populations (CRC: OR = 0.10, 95% CI = 2.76E-03-3.45, P = .20; rectal cancer: OR = 0.05, 95% CI = 9.14E-07-2.64E + 03, P = .59) or in Asian population (CRC: OR = 1.18, 95% CI = 0.92-1.52, P = .20), there was no horizontal diversity in the instrumental variables in the Mendelian randomization analyses of the present study (all F statistics >10), and no heterogeneity was found in the regression analyses. The findings from bidirectional 2-sample Mendelian randomization analyses indicate that there is no evidence of a bidirectional causal association between constipation and CRC. However, further investigation is warranted through additional clinical studies and trials to thoroughly explore the association between these 2 factors.

The comparison of risk factors for colorectal neoplasms at different anatomical sites

AIM

Both the clinical manifestation and molecular characteristics of colorectal cancer (CRC) vary according to the anatomical site. We explored the risk factors for four groups of colorectal neoplasms (CRN) at different anatomical sites.

METHODS

We extracted data from the database of Tianjin Colorectal Cancer Screening Program from 2010 to 2020. According to the CRN anatomical sites, patients were divided into four groups: the proximal colon group, the distal colon group, the rectum group, and the multiple colorectal sites. Binary logistic regression analysis was used to explore the differences in risk factors of CRN at different anatomical sites.

RESULTS

The numbers of patients with CRN in the proximal colon, distal colon, rectum, and multiple colorectal sites were 4023, 6920, 3657, and 7938, respectively. Male sex was associated with a higher risk from the proximal colon to the rectum. Advanced age and obesity were also significantly associated with overall colorectal CRN risk, but there were some differences between men and women. Smoking was associated with CRN risk only in the distal colon and rectum in both men and women. Frequent alcohol consumption and family history of CRC in first-degree relatives (FDRs) were associated with the risk of multisite colorectal CRN only in males.

CONCLUSIONS

We observed differences in advanced age, obesity, smoking, alcohol consumption, and family history of colorectal cancer at different anatomical sites of colorectal neoplasms. These factors vary by gender.

Body fatness over the life course and risk of serrated polyps and conventional adenomas

Serrated polyps (SPs) and conventional adenomas represent 2 distinct groups of colorectal premalignancy. The influence of early life adiposity on risk of these precursors remains unclear. Within the Nurses' Health Study, the Nurses' Health Study 2, and the Health Professionals Follow-up Study, we assessed body fatness during childhood using 9-level somatotype and obtained weight and body mass index (BMI) in adulthood. We used multivariable-adjusted logistic regression to examine the association of SPs and conventional adenomas with body fatness in early childhood (age 5), late childhood (age 10), early adulthood (age 18/21) and middle adulthood (baseline) and weight change during early-to-middle adulthood. During 18-20 years of follow-up, we documented 8,697 SPs and 10,219 conventional adenomas in 132,514 women; 2,403 SPs and 4,495 conventional adenomas in 29,207 men. We found a modest positive association of adiposity in early and late childhood with risk of SPs and conventional adenomas, with odds ratios ranging from 1.12 to 1.18 for comparison of extreme somatotypes groups. The associations were attenuated after adjusting for adulthood BMI but remained significant for conventional adenomas. No association with early life body fatness was found in men. Adulthood body fatness and weight change during early-to-middle adulthood showed positive relationships with SPs and conventional adenomas in both women and men, with stronger associations observed for SPs (p_{heterogeneity}  < 0.0001). Our findings indicated a potential role in development of colorectal cancer precursors of childhood body fatness in women, and early-to-middle adulthood weight gain and attained adiposity in both sexes.

Association between investigator-measured body-mass index and colorectal adenoma: a systematic review and meta-analysis of 168,201 subjects

The objective of this meta-analysis is to evaluate the odds of colorectal adenoma (CRA) in colorectal cancer screening participants with different body mass index (BMI) levels, and examine if this association was different according to gender and ethnicity. The EMBASE and MEDLINE were searched to enroll high quality observational studies that examined the association between investigator-measured BMI and colonoscopy-diagnosed CRA. Data were independently extracted by two reviewers. A random-effects meta-analysis was conducted to estimate the summary odds ratio (SOR) for the association between BMI and CRA. The Cochran’s Q statistic and I² analyses were used to assess the heterogeneity. A total of 17 studies (168,201 subjects) were included. When compared with subjects having BMI < 25, individuals with BMI 25–30 had significantly higher risk of CRA (SOR 1.44, 95% CI 1.30–1.61; I² = 43.0%). Subjects with BMI ≥ 30 had similarly higher risk of CRA (SOR 1.42, 95% CI 1.24–1.63; I² = 18.5%). The heterogeneity was mild to moderate among studies. The associations were significantly higher than estimates by previous meta-analyses. There was no publication bias detected (Egger’s regression test, p = 0.584). Subgroup analysis showed that the magnitude of association was significantly higher in female than male subjects (SOR 1.43, 95% CI 1.30–1.58 vs. SOR 1.16, 95% CI 1.07–1.24; different among different ethnic groups (SOR 1.72, 1.44 and 0.88 in White, Asians and Africans, respectively) being insignificant in Africans; and no difference exists among different study designs. In summary, the risk conferred by BMI for CRA was significantly higher than that reported previously. These findings bear implications in CRA risk estimation.

Obesity Increases Prevalence of Colonic Adenomas at Screening Colonoscopy: A Canadian Community-Based Study

BACKGROUND AND AIMS

Obesity is a risk factor for colorectal neoplasia. We examined the influence of obesity and metabolic syndrome (MetS) on prevalence of neoplasia at screening colonoscopy.

METHODS

We evaluated 2020 subjects undergoing first screening colonoscopy. Body mass index (BMI) was calculated at enrolment. Hyperlipidemia (HL), hypertension (HT), and diabetes mellitus (DM) were identified. Details of colonoscopy, polypectomy, and histology were recorded. Odds for adenomas (A) and advanced adenomas (ADV) in overweight (BMI 25.1-30) and obese (BMI > 30) subjects were assessed by multinomial regression, adjusted for covariates. Analyses included relationships between HL, HT, DM, age, tobacco usage, and neoplasia. Discriminatory power of HT, HL, DM, and BMI for neoplasia was assessed by binary logistic regression. Odds were calculated for neoplasia in each colonic segment related to BMI.

RESULTS

A and ADV were commoner in overweight and obese males, obese females, older subjects, and smokers. HL, HT, and DM were associated with increased odds for neoplasia, significantly for A with hypertension. BMI alone predicted neoplasia as well as HT, HL, DM, or combinations thereof. All segments of the colon were affected. Multiple polyps were particularly prevalent in the obese.

CONCLUSIONS

Obesity and MetS are risk factors for colonic neoplasia in a Canadian population.

Focus on genetic and epigenetic events of colorectal cancer pathogenesis: implications for molecular diagnosis

Originally, colorectal cancer (CRC) tumorigenesis was understood as a multistep process that involved accumulation of tumor suppressor genes and oncogenes mutations, such as APC, TP53 and KRAS. However, this assumption proposed a relatively limited repertoire of genetic alterations. In the last decade, there have been major advances in knowledge of multiple molecular pathways involved in CRC pathogenesis, particularly regarding cytogenetic and epigenetic events. Microsatellite instability, chromosomal instability and CpG island methylator phenotype are the most analyzed cytogenetic changes, while DNA methylation, modifications in histone proteins and microRNAs (miRNAs) were analyzed in the field of epigenetic alterations. Therefore, CRC development results from interactions at many levels between genetic and epigenetic amendments. Furthermore, hereditary cancer syndrome and individual or environmental risk factors should not be ignored. The difficulties in this setting are addressed to understand the molecular basis of individual susceptibility to CRC and to determine the roles of genetic and epigenetic alterations, in order to yield more effective prevention strategies in CRC patients and directing their treatment. This review summarizes the most investigated biomolecular pathways involved in CRC pathogenesis, their role as biomarkers for early CRC diagnosis and their possible use to stratify susceptible patients into appropriate screening or surveillance programs.

Association between constipation and colorectal cancer: systematic review and meta-analysis of observational studies

OBJECTIVES

Constipation is common in the community, and may affect survival adversely. An association between constipation and development of colorectal cancer (CRC) could be one possible explanation. We performed a systematic review and meta-analysis examining this issue.

METHODS

We searched MEDLINE, EMBASE, and EMBASE Classic (through July 2012). Eligible studies were cross-sectional surveys, cohort studies, or case-control studies reporting the association between constipation and CRC. For cross-sectional surveys and cohort studies, we recorded number of subjects with CRC according to the constipation status, and for case-control studies, number of subjects with constipation according to CRC status were recorded. Study quality was assessed according to published criteria. Data were pooled using a random effects model, and the association between CRC and constipation was summarized using an odds ratio (OR) with a 95% confidence interval (CI).

RESULTS

The search strategy identified 2,282 citations, of which 28 were eligible. In eight cross-sectional surveys, presence of constipation as the primary indication for colonoscopy was associated with a lower prevalence of CRC (OR=0.56; 95% CI 0.36-0.89). There was a trend toward a reduction in odds of CRC in constipation in three cohort studies (OR=0.80; 95% CI 0.61-1.04). The prevalence of constipation in CRC was significantly higher than in controls without CRC in 17 case-control studies (OR=1.68; 95% CI 1.29-2.18), but with significant heterogeneity, and possible publication bias.

CONCLUSIONS

Prospective cross-sectional surveys and cohort studies demonstrate no increase in prevalence of CRC in patients or individuals with constipation. The significant association observed in case-control studies may relate to recall bias.

The association between obesity and colorectal adenoma: systematic review and meta-analysis

OBJECTIVE

Obesity (body mass index [BMI] ≥30) or overweight (25 ≤ BMI ≤29.9) has been reported to be a risk factor for colorectal adenoma (CRA). However, this association remains controversial. The aim of this study was to determine the association between overweight or obesity and CRA.

DESIGN

Systematic review and meta-analysis were conducted using English language studies from EMBASE and MEDLINE. Appropriate observational studies were selected from 1966 through September 2011. Adjusted odds ratios (ORs) were extracted from each study.

RESULTS

One hundred and seventy full-text articles were reviewed after retrieving 1199 initial search results. Five studies in which BMI was treated as continuous variable, three studies in which BMI was dichotomized using a cutoff value of 25, three studies in which BMI was categorized into three groups using values of 22 and 25, and eight studies in which BMI was categorized into three groups using values of 25 and 30 were selected. Regarding risk for CRA, pooled OR [95% CI] of one increment increase in BMI was 1.02 [0.99-1.03] (random effects model [REM]), while that of BMI ≥ 25 was 1.27 [1.15-1.4] (Fixed effects model). Pooled ORs [95% CI] of BMI ≥ 22 and BMI ≥ 25 was 1.42 [0.69-2.9] [REM] and 1.81 [0.36-9.1] [REM], respectively. Pooled ORs [95% CI] of BMI ≥ 25 and BMI ≥ 30 was 1.16 [0.98-1.38] [REM] and 1.47 [1.18-1.83] [REM], respectively.

CONCLUSION

Obesity and overweight are significant risk factors for CRA. However, there are no data showing linear relationship between increasing BMI and CRA.

Body mass index category as a risk factor for colorectal adenomas: a systematic review and meta-analysis

OBJECTIVES

The association between increasing body weight and colorectal adenoma prevalence has been suggested to follow a similar pattern to excess weight and colorectal cancer, although the magnitude of this relationship has not been validated. The objective of this study was to quantify the association and dose-response relationship between body mass index (BMI) and colorectal adenoma prevalence in clinical trials.

METHODS

We systematically reviewed 23 studies (168,201 participants), which compared the prevalence of colorectal adenomas according to World Health Organization BMI categories. We assessed the effects of each BMI category on colorectal adenomas where odds ratio (OR) was used as a surrogate for effect size, and applied multivariate meta-analysis as a method of sensitivity analysis to evaluate the robustness of our findings and to analyze adenoma prevalence by multiple BMI categories simultaneously to assess for a dose-response relationship. Heterogeneity and publication bias were assessed.

RESULTS

Subjects with a BMI of ≥25 had a significantly higher prevalence of colorectal adenomas (OR=1.24 (95% confidence interval (CI): 1.16-1.33), P<0.01) when compared with those with BMI<25. Multivariate meta-analysis also confirmed a positive association between higher BMI categories and the prevalence of colorectal adenoma (BMI: 25-30 vs. BMI<25; OR=1.21 (95% CI: 1.07-1.38), P<0.01; BMI≥30 vs. BMI<25; OR=1.32 (95% CI: 1.18-1.48), P<0.01) and revealed a dose-response relationship.

CONCLUSIONS

The positive association between obesity and colorectal adenoma prevalence demonstrates an underlying dose-response relationship according to BMI. Colorectal centers may benefit from the timely screening of obese patients for colorectal adenomas in addition to clarifying the biological role of adiposity on colorectal tumor initiation and progression.

Alcohol consumption and colorectal cancer in a Mediterranean population: a case-control study

BACKGROUND

Alcohol is considered to be a cocarcinogen or a tumor promoter, and various studies have shown a linear dose-dependent association between alcohol consumption and colorectal cancer. However, a few studies suggest that moderate alcohol consumption may have a protective effect, similar to that in cardiovascular disease.

OBJECTIVE

The aim of this study was to evaluate the relationship of colorectal cancer to quantity and type of alcohol consumed.

DESIGN

This was case-control study.

SETTINGS

The study was conducted in the area of Attica, Greece.

PARTICIPANTS

A total of 250 consecutive patients with a first diagnosis of colorectal cancer were matched for age group and sex with 250 controls recruited from the community. The mean age was 63 (SD, 12) years for the patient group (147 men, 59%; 103 women, 41%) and 55 (SD, 13) years for the control group (112 men; 44.8%; 138 women, 55.2%).

MAIN OUTCOME MEASURES

Questionnaires were administered by trained interviewers to assess sociodemographic, clinical, and lifestyle characteristics, in addition to dietary habits and quantity and type of alcoholic beverages usually consumed during the preceding year. Adherence to the Mediterranean diet was evaluated with the MedDietScore (theoretical range, 0-55).

RESULTS

With intake of less than 12 g of alcohol per day as the reference, moderate alcohol intake (12-35 g/day) was associated with a significantly decreased likelihood of colorectal cancer in men (OR, 0.35; 95% CI, 0.16-0.74) and in women (OR, 0.40; 95% CI, 0.18-0.91). High alcohol intake (more than 48 g/day) was associated with an increased likelihood, which was significant in men (OR, 3.45; 95% CI, 1.35-8.83) but not in women (OR, 3.40; 95% CI, 0.50-22.92). Drinking red wine was associated with reduced odds of colorectal cancer, significant in men (OR, 0.47; 95% CI, 0.23-0.96) but not in women (OR, 0.54; 95% CI, 0.23-1.30). None of the associations between other beverage types and colorectal cancer were significant. Adherence to the Mediterranean diet was independently associated with lower odds of colorectal cancer overall (p < 0.001), in men (OR, 0.90; 95% CI, 0.83-0.97), and in women (OR, 0.87; 95% CI, 0.80-0.94).

LIMITATIONS

The major limitations of this study included the inability of a case-control design to determine causation and the potential for recall bias.

CONCLUSIONS

The association between quantity of alcohol consumed and the presence of colorectal cancer followed a J-shaped curve. While demonstrating the detrimental effect of consuming large amounts of alcohol, the results of this study suggest that moderate alcohol consumption exerts a protective effect on colorectal cancer in both men and women, possibly related to the effects of red wine.

Body mass index increases risk for colorectal adenomas based on meta-analysis

BACKGROUND & AIMS

There have been inconsistent results published about the relationship between excess body weight, expressed as increased body mass index (BMI), and risk of colorectal adenoma (CRA). We conducted a meta-analysis to explore this relationship. We focused on whether the relationship varied based on the sex of the study subjects, study design, features of the polyps, or potential confounders, including alcohol use, nonsteroidal anti-inflammatory drug use, smoking, and exercise.

METHODS

We identified studies by performing a literature search of Medline, EMBASE, and ISI Web of Science through July 31, 2011, and by searching the reference lists of pertinent articles. We analyzed 36 independent studies, which included 29,860 incident cases of CRA. Summary relative risks with their 95% confidence intervals (CIs) were calculated with a random-effects model. Between-study heterogeneity was assessed using Cochran's Q statistic and I(2) analyses.

RESULTS

Overall, a 5-unit increase in BMI (calculated as kg/m(2)) increased the risk for CRA (summary relative risk = 1.19; 95% CI: 1.13-1.26), although there was a high level of heterogeneity among studies (P(heterogeneity) < .001; I(2) = 76.8%). Subgroup analyses revealed that the increased risk of CRA in obese individuals was independent of race, geographic location, study design, sex, adenoma progression, and confounders. The association between increased BMI and risk for CRA was stronger for colon than rectal adenoma.

CONCLUSIONS

Based on a meta-analysis, increased BMI increases the risk for colon but not rectal adenoma. Unlike colorectal cancer, there is no sex difference in the relationship between increased BMI and risk of CRA.

Epigenetic biomarkers of colorectal cancer: Focus on DNA methylation

The original theory of the multi-step process of colorectal cancer (CRC), suggesting that the disease resulted from the accumulation of mutations in oncogenes and tumor suppressor genes in colonic mucosa cells, has been largely revised following the observation that epigenetic modifications of several genes occur in the average CRC genome. Therefore, the current opinion is that CRCs are the consequence of the accumulation of both mutations and epigenetic modifications of several genes. This mini-review article focuses on DNA methylation biomarkers in CRC. Recent large-scale DNA methylation studies suggest that CRCs can be divided into at least three-four subtypes according to the frequency of DNA methylation and those of mutations in key CRC genes. Despite hundreds of genes might be epigenetically modified in CRC cells, there is interest in the identification of DNA methylation biomarkers to be used for CRC diagnosis, progression, tendency to tissue invasion and metastasis, prognosis, and response to chemotherapeutic agents. Moreover, DNA methylation largely depends on one-carbon metabolism, the metabolic pathway required for the production of S-adenosylmethionine, the major intracellular methylating agent. Complex interactions are emerging among dietary one-carbon nutrients (folates, vitamin B6, vitamin B12, methionine, and others), their metabolic genes, CRC risk, and DNA methylation profiles in CRC. Moreover, active research is also focused on the possible contribution of folic acid dietary fortification during pregnancy and the possible methylation of CRC-related genes in the offspring.

Serum Interleukin-6, insulin, and HOMA-IR in male individuals with colorectal adenoma

PURPOSE

It is widely acknowledged that chronic low-grade inflammation plays a key role in the development of obesity-related insulin resistance and type 2 diabetes. The level of circulating interleukin-6 (IL-6), one of the major proinflammatory adipokines, is correlated with obesity and insulin resistance, which are known to be risk factors for colorectal adenoma. We examined the association between the circulating level of IL-6 and the presence of colorectal adenoma.

EXPERIMENTAL DESIGN

In a total colonoscopy-based cross-sectional study conducted between January and December 2008, serum levels of IL-6 were measured in samples of venous blood obtained from 336 male participants attending health checkups (118 individuals with colorectal adenoma and 218 age-matched controls) after an overnight fast.

RESULTS

In the colorectal adenoma group, the median levels of serum IL-6 (1.24 vs. 1.04 pg/mL; P = 0.01), triglyceride, insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) were to be significantly higher than those in the control group. When restricted to individuals with adenoma, levels of IL-6 were positively correlated with body mass index, insulin, and HOMA-IR. Multiple logistic analyses adjusted to include insulin or HOMA-IR showed that high levels of IL-6 were associated with the presence of colorectal adenoma. There was no significant interaction of IL-6 with HOMA-IR to modify this association.

CONCLUSIONS

Our findings suggest that increased serum levels of IL-6 are positively associated with the presence of colorectal adenoma in men, independently of insulin and HOMA-IR.

Genetics, cytogenetics, and epigenetics of colorectal cancer

Most of the colorectal cancer (CRC) cases are sporadic, only 25% of the patients have a family history of the disease, and major genes causing syndromes predisposing to CRC only account for 5-6% of the total cases. The following subtypes can be recognized: MIN (microsatellite instability), CIN (chromosomal instability), and CIMP (CpG island methylator phenotype). CIN occurs in 80-85% of CRC. Chromosomal instability proceeds through two major mechanisms, missegregation that results in aneuploidy through the gain or loss of whole chromosomes, and unbalanced structural rearrangements that lead to the loss and/or gain of chromosomal regions. The loss of heterozygosity that occur in the first phases of the CRC cancerogenesis (in particular for the genes on 18q) as well as the alteration of methylation pattern of multiple key genes can drive the development of colorectal cancer by facilitating the acquisition of multiple tumor-associated mutations and the instability phenotype.