Adult BMI Change and Risk of Colon Cancer in Postmenopausal Women

Overweight and obesity significantly increase colorectal cancer risk: a meta-analysis of 66 studies revealing a 25-57% elevation in risk

The incidence of colorectal cancer (CRC) has been steadily rising, and obesity has been identified as a significant risk factor. Numerous studies suggest a strong correlation between excess body weight and increased risk of CRC, but comprehensive quantification through pooled analysis remains limited. This study aims to systematically review and meta-analyze the existing literature to evaluate the association between obesity and CRC risk, considering variations across sex and study designs. A systematic literature search was conducted in PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science to identify randomized controlled trials and human clinical trials from 1992 to 2024. Statistical analysis was performed using the https://metaanalysisonline.com web application using a random effects model to estimate the pooled hazard rates (HR). Forest plots, funnel plots, and Z-score plots were utilized to visualize results. We identified 52 clinical trials and 14 case-control studies, encompassing a total of 83,251,050 and 236,877 subjects, respectively. The pooled analysis indicated that obesity significantly increased the prevalence of CRC (HR = 1.36, 95% CI = 1.24-1.48, p < 0.01). This effect was consistent across sexes, with HRs of 1.57 (95% CI = 1.38-1.78, p = 0.01) for males and 1.25 (95% CI = 1.14-1.38, p < 0.01) for females. Case-control studies specifically showed an effect, but with marginal significance only (HR = 1.27, 95% CI = 0.98-1.65, p = 0.07). The Z-score plot indicated the need for additional analysis in the case-control group. A significant heterogeneity was observed across studies in all four settings. This meta-analysis provides robust evidence that obesity is a significant risk factor for colorectal cancer, with an overall hazard rate indicating a 36% increased risk. The effect is pronounced across both sexes, with males showing a slightly higher risk compared to females. Although case-control studies showed a weaker association, the overall trend supports the link between obesity and CRC. These results underscore the importance of public health interventions aimed at reducing obesity to potentially lower the risk of colorectal cancer.

[Incidence of increase and decrease in Body Mass Index in middle-aged men and women: four-year follow-up]

The scope of this study was to analyze the incidence of increase and decrease in Body Mass Index (BMI) among middle-aged men and women according to sociodemographic characteristics and classification of nutritional status. It involved a population-based cohort of 689 adults aged 40 to 64 years followed up for four years. The proportion of reduction and increase in BMI (≥1 kg/m²) was verified according to sociodemographic variables and classification of nutritional status in the baseline by means of crude and adjusted Poisson regression. There was a higher incidence of reduced BMI among men in the 55-64 age group (RR: 1.78; 95%CI: 1.06-3.00), in those without a partner (RR: 1.85; 95%CI: 1.09-3.14), in those classified as overweight (RR: 2.06; 95%CI: 1.13-3.74) and in those classified as obese (RR: 2.33; 95%CI: 1.24-4.35), and among women in the 55-64 age group (RR: 1.43; 95%CI: 1.02-2.00) and in those classified as obese (RR: 2.10; 95%CI%: 1.30-3.38). The incidence of increased BMI was lower in the 55 to 64 age group among men (RR: 0.62; 95%CI: 0.41-0.95) and women (RR: 0.68; 95%CI: 0.49-0.95). These data are important for understanding the factors related to the variation of BMI and the elaboration of public policies aimed at the health care of middle-aged adults.

Excessive Body Fat at a Young Age Increases the Risk of Colorectal Cancer: A Systematic Review and Meta-Analysis

Overweight and obesity was considered as a risk factor for colorectal cancer (CRC), and CRC development may be due to exposure during one's youth. Metabolic syndrome and insulin resistance seem to play an important role in the underlying mechanisms. Even though several studies indicated the association between BMI at young age and CRC risks, an identified founding is still lacked. Therefore, we conducted a meta-analysis and a dose-response analysis to quantify the association between BMI at young age and CRC risks with relative accuracy. We searched the PubMed, Embase, Medline and Cochrane Library databases for articles published before Sep. 15, 2019. Fifteen articles with 2 520 091 participants were included. Risk for CRC was estimated using relative risks (RR) and 95% confidence intervals (CIs). Compared with individuals with normal weight, overweight and obese young adults had a significantly higher risk of CRC (relative risks (RR):18%, 95% CI:1.08, 1.28； RR:32%, 95% CI: 1.11, 1.56, respectively). However, this correlation may not exist for obese women (RR: 1.22, 95% CI: 0.99, 1.51); Overweight may not a risk factor for rectal cancer (RC) (RR: 1.12, 95% CI: 0.97, 1.29). In the dose-response analysis, we observed a linear relationship between BMI at a young age and CRC risk, with each 1 kg/m² increment associated with a 2% increased risk. Higher BMI at a young age was positively associated with CRC risk, which indicates that weight control since a young age was needed.

Changes in Adult BMI and Waist Circumference Are Associated with Increased Risk of Advanced Colorectal Neoplasia

BACKGROUND

Waist circumference (WC) is a stronger predictor of colon cancer (CRC) risk than body mass index (BMI). However, how well change in either WC or BMI predicts risk of advanced colorectal neoplasia (AN) is unclear.

AIMS

To determine the relationship between change in BMI and WC from early adulthood to later age and the risk of AN and which change measure is a stronger predictor.

METHODS

In 4500 adults, ages 50-80, with no previous neoplasia and undergoing screening colonoscopy, BMI and WC at age 21 and at time of screening were reported. Changes in BMI and WC were defined using universal risk cutoffs. Known CRC risk factors were controlled in the logistic models.

RESULTS

Overall, model statistics showed WC change (omnibus test χ ² = 10.15, 2 DF, p value = 0.006) was a statistically stronger predictor of AN than BMI change (omnibus test χ ² = 5.66, 5 DF, p value = 0.34). Independent of BMI change, participants who increased WC (OR 1.44; 95% CI 1.05-1.96) or maintained a high-risk WC (OR 2.50; 95% CI 1.38-4.53) at age 21 and at screening had an increased risk of AN compared to those with a low-risk WC. Study participants who were obese at age 21 and at screening had an increased risk of AN (OR 1.87; 95% CI 1.08-3.23) compared to those who maintained a healthy BMI. Maintaining an overweight BMI or increasing BMI was not associated with AN.

CONCLUSIONS

Maintaining an unhealthy BMI and WC throughout adult life may increase risk of AN. WC change may be a better predictor of AN than BMI change.

BMI and the risk of colorectal adenoma in African-Americans

OBJECTIVES

Obesity is associated with the activation of the molecular pathways that increase the risk of colorectal cancer. Increasing body mass index may accelerate the development of adenomatous polyps, the antecedent lesion of colorectal cancer. The aim of this study was to assess the BMI effect on the risk of colonic polyp and adenoma in African-American.

METHODS

The records of 923 patients who underwent colonoscopy were examined. Demographic and clinical data were collected before colonoscopy. Polyp and adenoma diagnosis were confirmed by pathology examinations.

RESULTS

Overall, 43% of the patients were male, median age was 57 years and 77% had BMI ≥ 25.0 kg/m(2) . The frequency of colorectal polyps and adenomas were 61 and 35%, respectively. BMI ≥ 25.0 (OR = 1.61, 95% CI = 1.14-2.26), smoking (OR = 1.61, 95% CI = 1.15-2.26) and history of colon polyps (OR = 1.64, 95% CI = 1.09-2.47) were associated with higher risk of colon polyp. BMI ≥ 25.0 (OR = 1.81, 95% CI = 1.24-2.62), age (OR = 1.04, 95% CI = 1.02-2.05 for each year), male gender (OR = 1.38, 95% CI = 1.02-1.86), and smoking (OR = 1.73, 95% CI = 1.23-2.42) were associated with higher risk of colon adenoma.

CONCLUSION

Male and overweight African-Americans are at higher risk of colorectal adenoma. The findings of this study could be applied for risk stratification and modifying the colorectal cancer prevention including screening guideline in African Americans.