The association between cigarette smoking and risk of colorectal cancer in a large prospective cohort from the United States

Poor health among smokers obtaining colonoscopy screening: making the case for cessation intervention

OBJECTIVES

Assess differences in perceived health status among individuals receiving colonoscopy screening based on smoking status.

STUDY DESIGN

Cross-sectional data were collected as part of a larger study investigating whether verbal and non-verbal communication and behaviors of gastroenterologists and nurses.

METHOD

Data for this study were collected between 2011 and 2013 among receiving colonoscopy screenings. Data were collected as part of a study assessing patients (n = 1785) undergoing colonoscopy screenings about their expectations, concerns, understanding of the procedure, and perceived health status. Differences between current, former and never smokers were analyzed using a one-way between subjects ANOVA, with a Scheffe post hoc.

RESULTS

Post hoc analyses revealed that current smokers were significantly different from former or never smokers on the following variables: days their physical health was not good, days their mental health was not good, days health influenced their activities, days pain influenced their ability to perform activities, perceived general health, and current anxiety.

CONCLUSION

This study looked at perceived health among individuals receiving colonoscopy screening by on smoking status, a relevant population based on the recent Surgeon Generals link. Former smokers reported similar health status across all variables as never smokers, suggesting the effect of quitting smoking on self-perceived health. With this link, tailored smoking cessation messages to smokers receiving colonoscopy screenings may be an excellent vantage point for a smoking cessation intervention.

Relationship between smoking and multiple colorectal cancers in patients with Japanese Lynch syndrome: a cross-sectional study conducted by the Japanese Society for Cancer of the Colon and Rectum

The positive correlation between smoking and cancer risk is well estimated in sporadic colorectal cancer, whereas little is known with regard to Lynch syndrome-associated colorectal cancer. A total of 118 familial colorectal cancer patients from the Hereditary Nonpolyposis Colorectal Cancer Registry and Genetic Testing Project of the Japanese Society for Cancer of the Colon and Rectum, were assessed to determine whether smoking alters the incidence of multiple colorectal cancers. In male patients with Lynch syndrome (n = 29), the incidence of multiple colorectal cancers in patients who had ever smoked (smoking duration: median of 19 years) was higher than that in those who never smoked (58.8% vs. 10.0%, P = 0.02). The cumulative risk for metachronous colorectal cancer was significantly higher in male Lynch syndrome patients who had previously smoked than in those who had never smoked (P = 0.03). Our data suggest that long-term cigarette smoking might be a strong risk factor for the development of multiple colorectal cancers in male Lynch syndrome patients.

Time trends in municipal distribution patterns of cancer mortality in Spain

BACKGROUND

New disease mapping techniques widely used in small-area studies enable disease distribution patterns to be identified and have become extremely popular in the field of public health. This paper reports on trends in the geographical mortality patterns of the most frequent cancers in Spain, over a period of 20 years.

METHODS

We studied the municipal spatial pattern of stomach, colorectal, lung, breast, prostate and urinary bladder cancer mortality in Spain across four quinquennia, spanning the period 1989-2008. Case data were broken down by town (8073 municipalities), period and sex. Expected cases for each town were calculated using reference rates for each five-year period. For map plotting purposes, smoothed municipal relative risks were calculated using the conditional autoregressive model proposed by Besag, York and Mollié, with independent data for each quinquennium. We evaluated the presence of spatial patterns in maps on the basis of models, calculating the variance in relative risk corresponding to the structured spatial component and the unstructured component, as well as the proportion of variance explained by the structured spatial component.

RESULTS

The mortality patterns observed for stomach, colorectal and lung cancer were maintained over the 20 years covered by the study. Prostate cancer and the tumours studied in women showed no defined spatial pattern, with the single exception of stomach cancer. The trend in spatial fractional variance indicated the possibility of a change in the spatial pattern in breast, bladder and colorectal cancer in women during the last five-year period. The paper goes on to discuss ways in which spatio-temporal data are depicted in the case of cancer, and review the risk factors that may possibly influence the respective tumours' spatial patterns.

CONCLUSION

In men, the marked geographical patterns of stomach, colorectal, lung and bladder cancer remained stable over time. Breast, colorectal and bladder cancer in women show signs of the possible appearance of a spatial pattern in Spain and should therefore be monitored.

Metabolites of tobacco smoking and colorectal cancer risk

Colorectal cancer is not strictly considered a tobacco-related malignancy, but modest associations have emerged from large meta-analyses. Most studies, however, use self-reported data, which are subject to misclassification. Biomarkers of tobacco exposure may reduce misclassification and provide insight into metabolic variability that potentially influences carcinogenesis. Our aim was to identify metabolites that represent smoking habits and individual variation in tobacco metabolism, and investigate their association with colorectal cancer. In a nested case-control study of 255 colorectal cancers and 254 matched controls identified in the Prostate, Lung, Colorectal and Ovarian cancer screening trial, baseline serum was used to identify metabolites by ultra-high-performance liquid-phase chromatography and mass spectrometry, as well as gas chromatography with tandem mass spectrometry. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by logistic regression. Self-reported current smoking was associated with serum cotinine, O-cresol sulfate and hydroxycotinine. Self-reported current smoking of any tobacco (OR = 1.90, 95% CI: 1.02-3.54) and current cigarette smoking (OR = 1.51, 95% CI: 0.75-3.04) were associated with elevated colorectal cancer risks, although the latter was not statistically significant. Individuals with detectable levels of hydroxycotinine had an increased colorectal cancer risk compared with those with undetectable levels (OR = 2.68, 95% CI: 1.33-5.40). Although those with detectable levels of cotinine had a suggestive elevated risk of this malignancy (OR = 1.81, 95% CI: 0.98-3.33), those with detectable levels of O-cresol sulfate did not (OR = 1.16, 95% CI: 0.57-2.37). Biomarkers capturing smoking behavior and metabolic variation exhibit stronger associations with colorectal cancer than self-report, providing additional evidence for a role for tobacco in this malignancy.

Tests and investigations for colorectal cancer screening

Worldwide, colorectal (CRC) is the third most common form of cancer, after lung and breast cancer, and the fourth most common cause of cancer death, although in developed countries CRC incidence is higher and it accounts for an even higher proportion of cancer deaths. Successful treatment of early-stage CRC confers substantial survival advantage, and there is now overwhelming evidence that screening average-risk individuals for CRC reduces the incidence and disease-specific mortality. In spite of considerable research for new biomarkers for CRC, the detection of blood in faeces remains the most effective screening tool. The best evidence to date for population-based CRC screening comes from randomised-controlled trials that used a guaiac-based faecal occult blood test (gFOBt) as the first-line screening modality, whereby test-positive individuals are referred for follow-up investigations, usually colonoscopy. A major innovation in the last ten years or so has been the development of other more analytically sensitive and specific screening techniques for blood in faeces. The faecal immunochemical test for haemoglobin (FIT) confers substantial benefits over gFOBt in terms of analytical sensitivity, specificity and practicality and FIT are now recommended for CRC screening by the European guidelines for quality assurance in colorectal cancer screening and diagnosis. The challenge internationally is to develop high quality CRC screening programmes for which uptake is high. This is especially important for developing countries witnessing an increase in the incidence of CRC as populations adopt more westernised lifestyles. This review describes the tests available for CRC screening and how they are being used worldwide. The reader will gain an understanding of developments in CRC screening and issues that arise in choosing the most appropriate screening test (or tests) for organised population-based screening internationally and optimising the performance of the chosen test (or tests). Whilst a wide range of literature has been cited, this is not a systematic review. The authors provide FOBT CRC screening for a population of 14.6 million in the south of England and the senior author (SPH) was the lead author of the European guidelines for quality assurance in colorectal cancer screening and diagnosis and leads the World Endoscopy Organization Colorectal Cancer Committee's Expert Working Group on 'FIT for Screening'.

Smoking, lower gastrointestinal endoscopy, and risk for colorectal cancer

BACKGROUND

Lower gastrointestinal endoscopy can decrease colorectal cancer risk strongly through detection and removal of adenomas. Thus, we aimed to investigate whether utilization of lower gastrointestinal endoscopy modifies the effect of lifetime smoking exposure on colorectal cancer risk in a population-based case-control study.

METHODS

In this study from Southern Germany including 2,916 patients with colorectal cancer and 3,044 controls, information about lifetime smoking and other risk factors was obtained from standardized interviews. Self-reported endoscopies were validated by medical records. Multivariate logistic regression was performed to investigate associations of smoking with colorectal cancer risk after stratification by utilization of lower gastrointestinal endoscopy in the preceding 10 years.

RESULTS

Median age of patients and controls was 69 and 70 years, respectively. Former regular smoking was associated with increased colorectal cancer risk in the group with no previous endoscopy [adjusted OR, 1.50; 95% confidence interval (CI), 1.28-1.75], whereas no association was found in the group with preceding endoscopy (OR, 1.05; CI, 0.83-1.33; P for interaction <0.01). Lower gastrointestinal endoscopy did not modify the association of smoking and colorectal cancer risk among current smokers and among the more recent quitters.

CONCLUSIONS

Our results suggest that the increased risk of colorectal cancer among former regular smokers is essentially overcome by detection and removal of adenomas at lower gastrointestinal endoscopy. However, risk of colorectal cancer was increased if smoking was continued into higher adult age.

IMPACT

The strong protective effect of lower gastrointestinal endoscopy may be compromised by continued smoking. Smoking cessation may increase the efficacy of lower gastrointestinal endoscopy.

DNA methylation as a long-term biomarker of exposure to tobacco smoke

BACKGROUND

Most biomarkers of exposure tend to have short half-lives. This includes cotinine, a metabolite of nicotine widely used to assess smoke exposure. Cotinine is thus unsuitable as a determinant of past exposure to cigarette smoke.

METHODS

We used bisulphite pyrosequencing of a set of four genomic loci (AHRR, 6p21, and two at 2q37) that had differential DNA methylation levels in peripheral blood DNA dependent on tobacco exposure to create a predictive model of smoking status.

RESULTS

Combining four gene loci into a single methylation index provided high positive predictive and sensitivity values for predicting former smoking status in both test (n = 81) and validation (n = 180) sample sets.

CONCLUSIONS

This study provides a direct molecular measure of prior exposure to tobacco that can be performed using the quantitative approach of bisulphite pyrosequencing. Epigenetic changes that are detectable in blood may more generally act as molecular biomarkers for other exposures that are also difficult to quantify in epidemiological studies.

Recent trends in incidence of five common cancers in 26 European countries since 1988: Analysis of the European Cancer Observatory

BACKGROUND

Individual country- and cancer site-specific studies suggest that the age-adjusted incidence of many common cancers has increased in European populations over the past two decades. To quantify the extent of these trends and the recent burden of cancer, here we present a comprehensive overview of trends in population-based incidence of the five common cancers across Europe derived from a new web-based portal of the European cancer registries.

METHODS

Data on incidence for cancers of the colon and rectum, prostate, breast, corpus uteri and stomach diagnosed from 1988 to 2008 were obtained from the European Cancer Observatory for cancer registries from 26 countries. Annual age-standardised incidence rates and average annual percentage changes were calculated.

RESULTS

Incidence of four common cancers in eastern and central European countries (prostate, postmenopausal breast, corpus uteri and colorectum) started to approach levels in northern and western Europe, where rates were already high in the past but levelled off in some countries in recent years. Decreases in stomach cancer incidence were seen in all countries.

DISCUSSION

Increasing trends in incidence of the most common cancers, except stomach cancer, are bad news to public health but can largely be explained by well-known changes in society in the past decades. Thus, current and future efforts in primary cancer prevention should not only remain focussed on the further reduction of smoking but engage in the long-term efforts to retain healthy lifestyles, especially avoiding excess weight through balanced diets and regular physical exercise.

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.

Effects of smoking and antioxidant micronutrients on risk of colorectal cancer

BACKGROUND & AIMS

Antioxidant intake has been reported to increase the risk of colorectal cancer (CRC) for smokers, yet reduce the risk for nonsmokers. We investigated the association between tobacco smoking and risk of colon or rectal cancer, and whether dietary and supplemental intake of the antioxidant vitamins A, C, E, β-carotene, selenium, zinc, and manganese affects the risk of CRC among smokers.

METHODS

Data on smoking habits and antioxidant intake were analyzed for 54,208 participants in the Danish Prospective Diet, Cancer and Health Study. Of these participants, 642 were diagnosed with colon cancer and 348 were diagnosed with rectal cancer. Hazard ratios and 95% confidence intervals were estimated using Cox proportional hazard models. Principal components were used to analyze intake of combinations of antioxidants.

RESULTS

Ever smoking increased the risk for CRC (hazard ratio, 1.19; 95% confidence interval, 1.03-1.37), especially for rectal cancer. Smoking for at least 20 years was associated with a 26% increase in risk of CRC, compared with never smokers, and smoking 20 g tobacco or more each day was associated with a 30% increase in risk. Smoking for more than 30 years, or more than 20 g tobacco each day, was associated with a 48% increase in risk of rectal cancer. We did not observe an interaction between smoking and antioxidant consumption on risk of CRC.

CONCLUSIONS

Tobacco smoking increases the risk for CRC. We did not observe that consumption of antioxidant micronutrients modulates the effects of smoking on CRC risk.

Epigenome-wide association study in the European Prospective Investigation into Cancer and Nutrition (EPIC-Turin) identifies novel genetic loci associated with smoking

A single cytosine-guanine dinucleotide (CpG) site within coagulation factor II (thrombin) receptor-like 3 (F2RL3) was recently found to be hypomethylated in peripheral blood genomic DNA from smokers compared with former and non-smokers. We performed two epigenome-wide association studies (EWAS) nested in a prospective healthy cohort using the Illumina 450K Methylation Beadchip. The two populations consisted of matched pairs of healthy individuals (n = 374), of which half went on to develop breast or colon cancer. The association was analysed between methylation and smoking status, as well as cancer risk. In addition to the same locus in F2RL3, we report several loci that are hypomethylated in smokers compared with former and non-smokers, including an intragenic region of the aryl hydrocarbon receptor repressor gene (AHRR; cg05575921, P = 2.31 × 10(-15); effect size = 14-17%), an intergenic CpG island on 2q37.1 (cg21566642, P = 3.73 × 10(-13); effect size = 12%) and a further intergenic region at 6p21.33 (cg06126421, P = 4.96 × 10(-11), effect size = 7-8%). Bisulphite pyrosequencing validated six loci in a further independent population of healthy individuals (n = 180). Methylation levels in AHRR were also significantly decreased (P < 0.001) and expression increased (P = 0.0047) in the lung tissue of current smokers compared with non-smokers. This was further validated in a mouse model of smoke exposure. We observed an association with breast cancer risk for the 2q37.1 locus (P = 0.003, adjusted for the smoking status), but not for the other loci associated with smoking. These data show that smoking has a direct effect on the epigenome in lung tissue, which is also detectable in peripheral blood DNA and may contribute to cancer risk.

A pooled analysis of smoking and colorectal cancer: timing of exposure and interactions with environmental factors

BACKGROUND

Considerable evidence suggests that cigarette smoking is associated with a higher risk of colorectal cancer (CRC). What is unclear, however, is the impact of quitting smoking on risk attenuation and whether other risk factors for CRC modify this association.

METHODS

We conducted a pooled analysis of eight studies, including 6,796 CRC cases and 7,770 controls, to evaluate the association between cigarette smoking history and CRC risk and to investigate potential effect modification by other risk factors.

RESULTS

Current smokers [OR, 1.26; 95% confidence interval (CI), 1.11-1.43] and former smokers (OR, 1.18; 95% CI, 1.09-1.27), relative to never smokers, showed higher risks of CRC. Former smokers remained at higher CRC risk, relative to never smokers, for up to about 25 years after quitting. The impact of time since quitting varied by cancer subsite: The excess risk due to smoking decreased immediately after quitting for proximal colon and rectal cancer but not until about 20 years post-quitting for distal colon cancer. Furthermore, we observed borderline statistically significant additive interactions between smoking status and body mass index [BMI; relative excess risk due to interaction (RERI]), 0.15; 95% CI, -0.01 to 0.31; P = 0.06] and significant additive interaction between smoking status and fruit consumption (RERI, 0.16; 95% CI, 0.01-0.30; P = 0.04).

CONCLUSION

CRC risk remained increased for about 25 years after quitting smoking, and the pattern of decline in risk varied by cancer subsite. BMI and fruit intake modified the risk associated with smoking.

IMPACT

These results contribute to a better understanding of the mechanisms through which smoking impacts CRC etiology.

The use of epidemiological measures to estimate the impact of primary prevention interventions on CHD, stroke and cancer outcomes: experiences from Herefordshire, UK

Background: CHD, stroke and cancers are the major causes of mortality in the UK and are responsible for significant amounts of morbidity and healthcare costs. This study examines the proportion of CHD, stroke and cancer owing to specific risk factors in Herefordshire, UK. It estimates the population impact of a number of interventions being implemented to reduce these risk factors, through the NHS Health Check program and the Herefordshire Health Improvement Plan. The present study also aims to demonstrate the value of epidemiological measures in providing evidence-based public health information in policy-making to aid decision makers when prioritizing investments and optimal use of resources.

Methods: The epidemiological measures–‘Population Attributable Risk’ and ‘Population Impact Measures’–were used to assess the impact of interventions to reduce the burden of CHD, stroke and cancer.

Results: Implementation of the NHS Health Check program will prevent 63 CHD events, 90 MI events and 125 stroke events, and one lung cancer over a period of 5 years. Reducing specific risk factors by 5% annually through the Health Improvement Plan will prevent 65 CHD events, 25 MI events, 140 stroke events, four lung cancer, one breast cancer and four colorectal cancer cases in Herefordshire if targets are met over a period of 5 years.

Conclusion: Physical inactivity and obesity are the major causes of CHD and stroke events (incidence and mortality) in Herefordshire. Their impact is greater than the combined effect of hypercholesterolemia and hypertension.

Epidemiological measures used in this study proved to be excellent tools in providing evidence-based public health information. Their use is strongly recommended to support prioritization of primary prevention interventions.

Adverse effects of smoking on postoperative outcomes in cancer patients

BACKGROUND

The possible negative effects of smoking on postoperative outcomes have not been well studied in cancer patients.

METHODS

We used the VA Surgical Quality Improvement Program (VASQIP) database for the years 2002-2008, which assesses preoperative risk factors and postoperative outcomes for patients undergoing major surgery within the VA healthcare system.

RESULTS

Compared with never smokers, prior smokers and current smokers with GI malignancies were significantly more likely to have surgical site infection (SSI) (odds ratio [OR], 1.25; 95% confidence interval [95% CI], 1.09-1.44) (OR, 1.20; 95% CI, 1.05-1.38), combined pulmonary complications (combined pulmonary outcome [CPO]: pneumonia, failure to wean from ventilator, reintubation) (OR, 1.60; 95% CI, 1.38-1.87) (OR, 1.96; 95% CI, 1.68-2.29), and return to the operating room (OR, 1.20; 95% CI, 1.03-1.39) (OR, 1.31; 95% CI, 1.13-1.53), respectively. Both prior and current smokers had a significantly higher mortality at 30 days (OR, 1.50; 95% CI, 1.19-1.89) (OR, 1.41; 95% CI, 1.08-1.82) and 1 year (OR, 1.22; 95% CI, 1.08-1.38) (OR, 1.62; 95% CI, 1.43-1.85). Thoracic surgery patients who were current smokers were more likely to develop CPO (OR, 1.62; 95% CI, 1.25-2.11) and mortality within 1 year (OR, 1.50; 95% CI, 1.17-1.92) compared with nonsmokers, but SSI rates were not affected by smoking status. Current smokers had a significant increase in postsurgical length of stay (overall 4.3% [P < .001], GI 4.7% [P = .003], thoracic 9.0% [P < .001]) compared with prior smokers.

CONCLUSIONS

Prior and current smoking status is a significant risk factor for major postoperative complications and mortality following GI cancer and thoracic operations in veterans. Smoking cessation should be encouraged prior to all major cancer surgery in the VA population to decrease postoperative complications and length of stay.

New developments in pancreatic cancer

Pancreatic adenocarcinoma presents in an advanced stage and has a dismal prognosis. Extensive recent research efforts have provided us with greater insight into the etiology of pancreatic cancer and have also improved our means of prognostication. Molecular analysis demonstrated that specific pathways involved in pancreatic carcinogenesis are perhaps more valuable to study than single genetic aberrations. Previous risk factors, including family history, body mass index, and current cigarette smoking, were validated and novel risks, such as ABO blood group alleles, were identified. Similar to other illnesses, combinations of healthful habits, such as not smoking, adhering to a Mediterranean dietary pattern, and engaging in physical activity, may decrease pancreatic cancer risk. Finally, CA 19-9 levels, the presence of diabetes mellitus, and a six-gene signature provided critical information regarding survival that could help guide treatment of individuals diagnosed with pancreatic adenocarcinoma.

Anatomic sites at elevated risk of second primary cancer after an index head and neck cancer

BACKGROUND

Patients with head and neck squamous cell carcinoma (HNSCC) are at significantly elevated risk of second primary malignancies (SPM), most commonly within the head and neck, lung, and esophagus (HNLE). Our objectives were to quantify the excess risk of SPM across all anatomic sites in which SPM risk is meaningfully elevated, including non-HNLE sites, in a large cohort of US patients.

METHODS

Population-based analysis of 75,087 patients with HNSCC in the SEER program, quantifying excess SPM risk by integrating relative (standardized incidence ratio; SIR) and absolute (excess absolute risk per 10,000 person-years at risk; EAR) statistics.

RESULTS

In HNSCC patients, the SIR of a second primary solid cancer was 2.2 (95% CI 2.1-2.2), corresponding to EAR of 167.7 additional cases per 10,000 person-years at risk. Over 1 year, 60 patients would need to be followed to observe one excess SPM. Lung cancer burden was most markedly elevated in absolute terms (EAR = 75.2), followed by HN (EAR = 59.8), esophageal (EAR = 14.2), and colorectal (EAR = 4.3) cancers. Lesser but significant excess risks were also observed for cancers of the bladder, liver, stomach, pancreas, kidney, salivary glands, nasopharynx, uterine cervix, and lymphoma.

CONCLUSIONS

Data from a large population-based US cohort reveals that HNSCC patients experience markedly excess risk of SPM, predominantly in the HNLE sites. Furthermore, the risk of SPM is also meaningfully elevated, although to a lesser degree, in multiple other tobacco-associated sites.

Smoking, snus use and risk of right- and left-sided colon, rectal and anal cancer: a 37-year follow-up study

Although some authorities consider smoking to be an established risk factor for colorectal cancer, the international literature is not entirely consistent. Further, only 1 study has addressed the association with smokeless tobacco and none with Scandinavian moist snuff (snus). This retrospective cohort study included 336,381 male Swedish construction workers with detailed information on tobacco use at cohort entry in 1971-1992. Complete follow-up through 2007 was accomplished by means of linkage to population and health registers. Hazard ratios (HRs) and 95% confidence intervals (CIs) derived from Cox proportional hazards regression models estimated relative risks, adjusted for age and body mass index. Subjects who were never-users of any tobacco served as reference. After up to 37 years of follow-up, pure smoking was associated with a marginally increased risk of colon cancer (HR 1.08, 95% CI 0.99-1.19), a modestly elevated risk of rectal cancer (HR 1.16, 95% CI 1.04-1.30) and a substantial excess risk of anal cancer (HR 2.41, 95% CI 1.06-5.48). Snus use was not significantly associated with an increased risk of colorectal or anal cancer, although the point estimate for colon cancer was similar to that observed among smokers. Swedish data provide meager support for the association between tobacco use and colorectal cancer. A general tendency among Swedish men to quit smoking in recent decades might have attenuated true associations. A link between smoking and anal cancer was confirmed.

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.

Primary prevention of colorectal cancer

Colorectal cancer has been strongly associated with a Western lifestyle. In the past several decades, much has been learned about the dietary, lifestyle, and medication risk factors for this malignancy. Although there is controversy about the role of specific nutritional factors, consideration of dietary pattern as a whole appears useful for formulating recommendations. For example, several studies have shown that high intake of red and processed meats, highly refined grains and starches, and sugars is related to increased risk of colorectal cancer. Replacing these factors with poultry, fish, and plant sources as the primary source of protein; unsaturated fats as the primary source of fat; and unrefined grains, legumes and fruits as the primary source of carbohydrates is likely to lower risk of colorectal cancer. Although a role for supplements, including vitamin D, folate, and vitamin B6, remains uncertain, calcium supplementation is likely to be at least modestly beneficial. With respect to lifestyle, compelling evidence indicates that avoidance of smoking and heavy alcohol use, prevention of weight gain, and maintenance of a reasonable level of physical activity are associated with markedly lower risks of colorectal cancer. Medications such as aspirin and nonsteroidal anti-inflammatory drugs and postmenopausal hormones for women are associated with substantial reductions in colorectal cancer risk, though their utility is affected by associated risks. Taken together, modifications in diet and lifestyle should substantially reduce the risk of colorectal cancer and could complement screening in reducing colorectal cancer incidence.