Primary prevention of colorectal cancer: are we closer to reality?

Physical Activity and Gastrointestinal Cancer Risk: A Review

Introduction: Western lifestyle characterized by increased consumption of red meat, fat, processed food, smoking, alcohol drinking, lower consumption of vegetables and physical inactivity has been associated with a higher gastrointestinal cancer risk. Digestive system cancers are diagnosed at late stages when they show poor response to treatment and are associated with a high mortality rate. Colorectal, gastric, esophageal and pancreatic cancers are among the most common cancers worldwide. Studies show that more than 50% of gastrointestinal cancers develop as a result of inappropriate lifestyle. An inverse association between physical activity and many chronic diseases has been proved so far. However, the association between physical activity and some gastrointestinal cancers is still controversial. This study was aimed to determine the association between physical activity and gastrointestinal cancers risk.

Methods: We conducted a comprehensive search of English and Persian databases from February 2007 till December 2017, for studies investigating the association of physical activity and risk of gastrointestinal cancers. Finally, after reading full text of articles, 123 studies were included.

Results: Physical activity can be helpful in reducing the risk of gastrointestinal cancer, especially colon and pancreatic cancers. The risk reduction is not similar for different types of gastrointestinal cancers and also among males and females.

Conclusion: Different types of physical activity are associated with a lower risk of gastrointestinal cancer. However, it is unknown which type and intensity of physical activity are associated with a protective effect against gastro-intestinal cancer.

Prevention of Colorectal Neoplasia

Colorectal cancer (CRC) is one of the leading causes of cancer-related morbidity and mortality worldwide. There are well-established screening protocols involving fecal testing, radiographic, and endoscopic evaluations that have led to decreased incidence and mortality of CRC in the United States. In addition to screening for CRC, there is interest in preventing colorectal neoplasia by targeting the signaling pathways that have been identified in the pathway of dysplasia progressing to carcinoma. This review will detail the efficacy of multiple potential preventative strategies including lifestyle changes (physical activity, alcohol use, smoking cessation, and obesity); dietary factors (dietary patterns, calcium, vitamin D, fiber, folate, and antioxidants and micronutrients); and chemopreventive agents (nonsteroidal anti-inflammatory drugs, statins, metformin, bisphosphonates, and postmenopausal hormonal therapy).

Colorectal cancer mortality among Hispanics in California: differences by neighborhood socioeconomic status and nativity

BACKGROUND

Socioeconomic status (SES) plays an important role in colorectal cancer (CRC) mortality, although the independent and joint effects with nativity and neighborhood factors have yet to be evaluated.

METHODS

With nearly one-third of all US Hispanics residing in California, the authors obtained information from the California Cancer Registry to examine the associations between neighborhood SES and mortality in all 33,146 Hispanic individuals diagnosed with CRC from 1988 through 2010, with a particular focus on associations among US-born and foreign-born Hispanics. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (95% CI) for overall and CRC-specific mortality.

RESULTS

Hispanics residing in lower SES neighborhoods demonstrated a higher rate of overall and CRC-specific mortality than those residing in high SES neighborhoods (SES quintile 1[low] vs quintile 5 [high]: HR, 1.15 [95% CI, 1.05-1.26] and HR, 1.16 [95% CI, 1.03-1.30], respectively). Nativity modified the associations between SES and mortality (P for interaction, .02 for overall and P for interaction, .01 for CRC-specific mortality) such that the SES associations were observed only among US-born (P for trend < .01 for overall and CRC-specific mortality) but not among foreign-born Hispanics.

CONCLUSIONS

Neighborhood SES demonstrates significant differential effects on overall and CRC-specific mortality between US-born and foreign-born Hispanics. Future efforts should investigate the underlying contextual and individual-level factors that could account for these differential associations by nativity.

Combined impact of healthy lifestyle factors on colorectal cancer: a large European cohort study

BACKGROUND

Excess body weight, physical activity, smoking, alcohol consumption and certain dietary factors are individually related to colorectal cancer (CRC) risk; however, little is known about their joint effects. The aim of this study was to develop a healthy lifestyle index (HLI) composed of five potentially modifiable lifestyle factors--healthy weight, physical activity, non-smoking, limited alcohol consumption and a healthy diet, and to explore the association of this index with CRC incidence using data collected within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.

METHODS

In the EPIC cohort, a total of 347,237 men and women, 25- to 70-years old, provided dietary and lifestyle information at study baseline (1992 to 2000). Over a median follow-up time of 12 years, 3,759 incident CRC cases were identified. The association between a HLI and CRC risk was evaluated using Cox proportional hazards regression models and population attributable risks (PARs) have been calculated.

RESULTS

After accounting for study centre, age, sex and education, compared with 0 or 1 healthy lifestyle factors, the hazard ratio (HR) for CRC was 0.87 (95% confidence interval (CI): 0.44 to 0.77) for two factors, 0.79 (95% CI: 0.70 to 0.89) for three factors, 0.66 (95% CI: 0.58 to 0.75) for four factors and 0.63 (95% CI: 0.54 to 0.74) for five factors; P-trend<0.0001. The associations were present for both colon and rectal cancers, HRs, 0.61 (95% CI: 0.50 to 0.74; P for trend<0.0001) for colon cancer and 0.68 (95% CI: 0.53 to 0.88; P-trend<0.0001) for rectal cancer, respectively (P-difference by cancer sub-site=0.10). Overall, 16% of the new CRC cases (22% in men and 11% in women) were attributable to not adhering to a combination of all five healthy lifestyle behaviours included in the index.

CONCLUSIONS

Combined lifestyle factors are associated with a lower incidence of CRC in European populations characterized by western lifestyles. Prevention strategies considering complex targeting of multiple lifestyle factors may provide practical means for improved CRC prevention.

Contribution of behavioral risk factors and obesity to socioeconomic differences in colorectal cancer incidence

BACKGROUND

Health behaviors are known risk factors for colorectal cancer and are more common in low socioeconomic status (SES) populations. We evaluated the extent to which behavioral risk factors and body mass index (BMI) explain SES disparities in colorectal cancer incidence, overall and by tumor location.

METHODS

We analyzed prospective National Institutes of Health-AARP Diet and Health Study data on 506 488 participants who were recruited in 1995-1996 from six US states and two metropolitan areas and followed through 2006. Detailed baseline data on risk factors for colorectal cancer, including health behaviors, were obtained using questionnaires. SES was measured by self-reported education and census-tract data. The outcome was primary incident invasive colorectal adenocarcinoma. Poisson regression was used to estimate the association between SES and risk of incident colorectal cancer, with adjustment for age, sex, race and ethnicity, family history, and state of residence. The model estimates were used to derive percentage mediation by behavioral risk factors; bias-corrected 95% confidence intervals were obtained through bootstrap techniques.

RESULTS

Seven-thousand six-hundred seventy-six participants developed colorectal cancer during follow-up. SES differences in prevalence of physical inactivity, unhealthy diet, smoking, and unhealthy weight each explained between 11.3% (BMI) and 21.6% (diet) of the association between education and risk of colorectal cancer and between 8.6% (smoking) and 15.3% (diet) of the association between neighborhood SES and risk of colorectal cancer. Health behaviors and BMI combined explained approximately 43.9% (95% CI = 35.1% to 57.9%) of the association of education and 36.2% (95% CI = 28.0% to 51.2%) of the association of neighborhood SES with risk of colorectal cancer. The percentage explained by all factors and BMI combined was largest for right colon cancers and smallest for rectal cancers.

CONCLUSION

A substantial proportion of the socioeconomic disparity in risk of new-onset colorectal cancer, and particularly of right colon cancers, may be attributable to the higher prevalence of adverse health behaviors in low-SES populations.

Contribution of NAD(P)H quinone oxidoreductase 1 (NQO1) Pro187Ser polymorphism and risk of colorectal adenoma and colorectal cancer in Caucasians: a meta-analysis

BACKGROUND AND AIMS

The effects of polymorphism of NAD(P)H quinone oxidoreductase 1 (NQO1 Pro187Ser, rs1800566) on the risks of colorectal adenoma and cancer have been widely studied and results remain controversial. Therefore, the aim of this meta-analysis was to quantitatively assess the relationships.

METHODS

Databases of Medline, Embase and Wanfang were retrieved until May 15, 2011. Pooled odds ratio (OR) and 95% confidence interval (95% CI) as effect sizes were calculated by using fixed- or random-effect model. Cochrane Q-test was used to explore between-study heterogeneity; p <0.10 indicated statistical significance.

RESULTS

A total of 12 case-control studies with 11,700 individuals (including 5528 cases and 6172 controls) were included in this meta-analysis. Of these studies, four studies conducted in Caucasian populations were for colorectal adenoma, and eight studies were for colorectal cancer. NQO1 187Ser allele was significantly associated with increased risk of colorectal adenoma in co-dominant and dominant comparison models (OR = 1.07, 95% CI = 1.04-1.32 for ProSer vs. ProPro and OR = 1.19, 95% CI = 1.06-1.33 for Ser carries vs. ProPro), without between-study heterogeneity. Overall, NQO1 Pro187Ser was not associated with risk of colorectal cancer, without between-study heterogeneity. Subgroup analyses indicated that Ser allele was significantly associated with increased risk of colorectal cancer for Caucasians (OR = 1.14, 95% CI = 1.00-1.30 for ProSer vs. ProPro and OR = 1.16, 95% CI = 1.02-1.31 for Ser carries vs. ProPro).

CONCLUSIONS

This meta-analysis suggested that Ser allele of NQO1 Pro187Ser significantly contributed to the increased risks of colorectal adenoma and cancer in Caucasians.