Should smokers be considered a high-risk group for colorectal cancer?

Association of individual and community factors with C-reactive protein and 25-hydroxyvitamin D: Evidence from the National Health and Nutrition Examination Survey (NHANES)

Many individual and community/neighborhood factors may contribute to inflammation and vitamin D deficiency leading to the development of chronic diseases. This study examined the associations of serum C-reactive protein (CRP) and 25-hydroxyvitamin D [25(OH)D] levels with individual and community/neighborhood (tract-level or county-level) factors using a nationally representative sample from 2001-2006 National Health and Nutrition Examination Survey (NHANES). Data from the 2001-2006 waves of the continuous NHANES was merged with the 2000 census and other neighborhood data sources constructed using geographic information system. Associations between multilevel factors and biomarker levels were assessed using multilevel random-intercept regression models. 6643 participants aged 19-65 (3402 men and 3241 women) were included in the analysis. Family income-to-needs ratio was inversely associated with CRP (P=0.002) and positively associated with 25(OH)D levels (P=0.0003). County crime rates were positively associated with CRP (P=0.007) and inversely associated with 25(OH)D levels (P=0.0002). The associations with income-to-needs ratio were significant in men [CRP; P=0.005; 25(OH)D, P=0.005] but not in women. For county crime rates, the association was only significant in women for CRP (P=0.004) and was significant in both men (P=0.01) and women (P=0.001) for 25(OH)D. Additionally, overall CRP was positively associated with age (P<0.0001), female sex (P<0.0001), Hispanic race/ethnicity (P=0.0001), current smokers (P<0.0001), body mass index (BMI, P<0.0001), and participants who were US-born (P=0.02). Non-Hispanic black (P<0.0001) and Hispanic race/ethnicity (P<0.0001), current smoker (P=0.047), and higher BMI (P<0.0001) were associated with lower serum 25(OH)D levels. No significant associations were observed between other community/neighborhood variables and serum CRP and 25(OH)D levels. The current results suggest that family income-to-needs ratio and county crime rate may be important contributors to chronic inflammation and vitamin D status.

Risk of colorectal cancer associated with active smoking among female teachers

PURPOSE

The objective of this study was to examine the risk of colorectal cancer associated with active smoking among members of the California Teachers Study (CTS), a large cohort of female public school employees for whom highly detailed smoking information is available.

METHODS

The analysis was conducted among the 122,264 CTS participants who lived in California at cohort entry in 1995/1996, had no prior history of colorectal cancer, and provided detailed smoking information. 1,205 cases of invasive colorectal cancer prospectively diagnosed in 1995-2009 were identified from the California Cancer Registry, including 650 in the proximal colon, 267 in the distal colon, and 288 in the rectum. Hazard ratios and 95% confidence intervals were estimated using Cox proportional hazards models, stratified by age at cohort entry, and adjusted for race/ethnicity.

RESULTS

Compared to never smokers, current smokers had an approximately 30% increased risk of colorectal cancer. Overall, a slightly elevated risk was also noted for former smokers. Among former smokers, risks appeared to remain elevated for up to 20 years following cessation. Risks among former and current smokers increased with greater intensity and duration of smoking. Little evidence for heterogeneity in risk was noted for colon versus rectal cancer or for different subsites within the colon.

CONCLUSIONS

These results provide convincing evidence that heavy and/or long-term smoking is a risk factor for cancers of the colon and rectum. Such evidence should be considered when updating screening guidelines to include targeting people with long active smoking histories.

Risk factors for colorectal cancer in patients with multiple serrated polyps: a cross-sectional case series from genetics clinics

Background

Patients with multiple serrated polyps are at an increased risk for developing colorectal cancer (CRC). Recent reports have linked cigarette smoking with the subset of CRC that develops from serrated polyps. The aim of this work therefore was to investigate the association between smoking and the risk of CRC in high-risk genetics clinic patients presenting with multiple serrated polyps.

Methods and Findings

We identified 151 Caucasian individuals with multiple serrated polyps including at least 5 outside the rectum, and classified patients into non-smokers, current or former smokers at the time of initial diagnosis of polyposis. Cases were individuals with multiple serrated polyps who presented with CRC. Controls were individuals with multiple serrated polyps and no CRC. Multivariate logistic regression was performed to estimate associations between smoking and CRC with adjustment for age at first presentation, sex and co-existing traditional adenomas, a feature that has been consistently linked with CRC risk in patients with multiple serrated polyps. CRC was present in 56 (37%) individuals at presentation. Patients with at least one adenoma were 4 times more likely to present with CRC compared with patients without adenomas (OR = 4.09; 95%CI 1.27 to 13.14; P = 0.02). For females, the odds of CRC decreased by 90% in current smokers as compared to never smokers (OR = 0.10; 95%CI 0.02 to 0.47; P = 0.004) after adjusting for age and adenomas. For males, there was no relationship between current smoking and CRC. There was no statistical evidence of an association between former smoking and CRC for both sexes.

Conclusion

A decreased odds for CRC was identified in females with multiple serrated polyps who currently smoke, independent of age and the presence of a traditional adenoma. Investigations into the biological basis for these observations could lead to non-smoking-related therapies being developed to decrease the risk of CRC and colectomy in these patients.

Smokers as a high-risk group: data from a screening population

GOAL

To determine the number of pack-years exposure associated with a 2-fold increase risk for significant colorectal neoplasia and to examine the risk of smoking in younger patients.

BACKGROUND

Cigarette smoking has been shown to be a significant risk factor for colorectal neoplasia and may be used to stratify patients for screening or triaging of screening resources. However, more information is needed regarding the amount of exposure required to significantly increase by 2-fold an individual's risk for colorectal neoplasia.

METHODS

Data collected for 2707 patients presenting for screening colonoscopy included tobacco use measured in pack-years and known risk factors for colorectal neoplasia. Our outcome was endoscopically detected significant colorectal neoplasia that included large (>1 cm) tubular adenomas, villous adenomas, multiple (3 or more) adenomas, high-grade dysplasia, and adenocarcinoma.

RESULTS

Patients who smoked more than 30 pack-years were more than 2 times more likely to have significant colorectal neoplasia than patients who never smoked (odds ratio: 2.40; 95% confidence interval: 1.65-3.50). For patients aged 40 to 49 years, smokers were more likely than nonsmokers to have significant colorectal neoplasia (odds ratio: 2.71; 95% confidence interval: 1.05-6.97).

CONCLUSIONS

Patients who have smoked more than 30 pack-years had a more than 2-fold increase for significant colorectal neoplasia as compared with nonsmokers. The increased risk was also observed in younger patients. Our data have implications for screening guidelines.

Cigarette smoking and risk of colorectal cancer among Norwegian women

OBJECTIVE

The association between cigarette smoking and colorectal cancer (CRC) is still not established. In 2002, Norwegian women had the second highest incidence of CRC in the world. A large proportion of Norwegian women are ever smokers. We examined the association between cigarette smoking and CRC incidence among Norwegian women.

METHODS

We followed 68,160 women, aged 30-69 years, from the Norwegian Women and Cancer Study who completed a questionnaire in 1996 or 1998 by linkages to national registers through 31 December 2005. Rate ratios (RRs) and 95% confidence intervals (CIs) were estimated by fitting Cox proportional hazard models. Subsequently, we estimated the population attributable fraction.

RESULTS

Altogether, 425 incident cases of primary, invasive CRC were identified. Ever smokers had a 20% increased risk of CRC (RR = 1.2; 95% CI = 1.0-1.5), a 30% increased risk of colon (RR = 1.3; 95% CI = 1.0-1.7), and a 10% increased risk of rectal (RR = 1.1; 95% CI = 0.7-1.5) cancer compared to never smokers. The population attributable fraction was estimated to be 12% which indicated that approximately one in eight of the CRC cases could have been prevented at a population level.

CONCLUSION

Our results support the hypothesis that cigarette smoking is a preventable cause of CRC among women.

Le tabac et l'alcool augmentent le risque d'adénomes et de cancers colorectaux

OBJECTIVE

To analyze the associations between lifestyle factors and colorectal adenomas or cancers in a population 50-74 years old.

METHOD

The study population underwent colonoscopy after positive fecal occult blood test in Health examination centers of the French general health insurance. The two sets of cases (n= 674 cancers, n=2618 adenomas) were compared with controls (n=5456). Associations between risk of colorectal disease and health data (mainly tobacco and alcohol consumption, physical activity, obesity, and laboratory test results) were analyzed with logistic regression models to estimate odds ratios.

RESULTS

The probability of colorectal cancer or adenoma was statistically associated with age (60 years or older in men and women). A significant relation between these diseases was observed with smoking (in both smokers and ex-smokers) and with alcohol consumption, with odds ratios above 1.30. The other risk factors studied were not significantly associated with these colorectal diseases.

CONCLUSION

This result provides still more evidence of the need for actions against these risk behaviors.

Clinical characteristics of synchronous colorectal cancer are different according to tumour location

AIMS

The purpose of this study was to investigate the clinical characteristics of synchronous cancer patients, with particular attention given to variations in tumour location.

METHODS

A retrospective evaluation of 249 synchronous cancer cases out of 3061 consecutive colorectal cancer patients.

RESULTS

Multivariate analysis of risk factors for synchronous cancer according to tumour location revealed that male gender was a significant risk for synchronous lesions in the left colon only (odds ratio=2.05, 95% confidence interval 1.34-3.13). Meanwhile, aging was a risk factor for synchronous cancer in the right colon only (odds ratio=1.05, 95% confidence interval 1.02-1.08), and in both sides of the colon (odds ratio=1.03, 95% confidence interval 1.01-1.05), but not in the left colon only (odds ratio=0.98, 95% confidence interval 0.97-1.00). In addition, patients with synchronous lesions in the right colon only tended to have adenomas in the right colon, while those with synchronous lesions in the left colon only tended to have adenomas in the left colon (each P value <0.05).

CONCLUSION

The risk factors and status of concurrent adenomas of synchronous cancer cases varied according to tumour location, suggesting that the colonic site susceptible to neoplasia varies according to patient characteristics.

Lifestyle as a predictor for colonic neoplasia in asymptomatic individuals

Background

Lifestyle is a well-established risk factor for colorectal cancer (CRC) and is also found to be associated with occurrence of adenomas. In the present study we evaluated risk factors for both low-risk adenomas and advanced neoplasia in asymptomatic individuals using a single-paged questionnaire. Aiming to see if the questionnaire was a useful tool in picking up high-risk individuals.

Methods

A cross-sectional study was carried out within a randomised controlled colorectal cancer screening trial (n = 6961). The population comprised men and women born between 1946 and 1950. Before screening in year 2001 they were asked to fill in a questionnaire about their present lifestyle. Cases were categorised according to the most severe findings at screening. Analyses were then conducted to find risk factors associated with the presence of either low-risk adenomas or advanced neoplasia.

Results

The response rate among attendees was 97% (3998/4111). Among these, 3447 (86%) had no neoplasia, 443 (11%) had low-risk adenomas, and 108 (3%) had advanced neoplasia. Low-risk adenomas were significantly associated with current smoking, and obesity. Participants with advanced neoplasia had a two-fold increased risk of not adhering to any of the selected lifestyle recommendations compared to controls. However, current smoking was the only variable that reached statistical significance in the multivariate analysis for these lesions. A dose-response relationship to the consumption of cigarettes per day was shown, where OR was 2.04 (CI 1.07–3.89) for the lowest consumption category.

Conclusion

The present findings indicate that a short questionnaire may be adequate in picking up the most consistent associations between lifestyle risk factors and colorectal neoplasia. Smoking and BMI were found to be the most significant risk factors for neoplasia, but adhering to recommendations on diet, and physical activity seems also to be of importance.