Tobacco smoking and colorectal cancer: a population-based case-control study in Newfoundland and Labrador

Characteristics of Interval Colorectal Cancer: A Canadian Retrospective Population-Level Analysis from Newfoundland and Labrador

Interval colorectal cancers (I-CRCs) arise during the interval time period between scheduled colonoscopies. Predicting which patients are at risk of I-CRCs remains an elusive undertaking, but evidence would suggest that most I-CRCs arise from lesions missed on index endoscopy. The procedural factors that lead to missed lesions are numerous and lack consensus in the literature. In Canada, the province of Newfoundland and Labrador has the highest incidence of CRCs. In this study our aim was to examine I-CRCs (3-60 months after last colonoscopy) in NL through a population-level analysis covering 67% of the province from 2001-2018. We estimated the I-CRC rate to be up to 9.3%. Median age of I-CRC diagnosis was 67.1 years with an interval time of 2.9 years. About 57% of these tumors occurred proximal to the splenic flexure, with 53% presenting as local disease. No temporal differences were observed in interval time or tumor distribution. On univariate and multivariable logistical regression, risk of right-sided I-CRC did not correlate to the index colonoscopy indication, bowel preparation quality, size of largest polyp removed, colonoscopy completion rate, or stage at presentation. Improvements in synoptic reporting utilization and national registries are needed to identity risk factors and reduce I-CRC frequency.

Diet and Genetic Risk Factors of Colorectal Cancer in Palestine: A Case-Control Study

To add evidence to the limited data available on colorectal cancer (CRC) from Palestine, we examine the risk factors associated with CRC using a matched hospital-based case-control study. A structured questionnaire was used to collect data from 105 cases and 105 controls. A multivariable conditional regression model was used to adjust for the association between study factors and CRC risk. In the model, compared with controls, cases from villages were significantly less likely to have CRC (Adjusted Odds Ratio, AOR = 0.194); taking aspirin lowered the likelihood of CRC by 24%; and having a multiple birth sibling by 33%. Also, the likelihood of CRC was lowered significantly by consuming five servings of fruits/vegetables per week or more (5-6 servings: AOR = 0.21, 7-8 servings per week: AOR = 0.04). However, cases had a significantly higher likelihood of CRC if they consumed 2-4 servings of grilled red meat per week (AOR = 4.25); smoked (AOR = 4.38); had a sedentary lifestyle (AOR = 2.53); reported parental consanguinity (AOR = 3.88); or had a family history of cancer (AOR = 6.39). Our results confirmed the association between CRC and red meat intake and smoking, and proved that parental consanguinity and family history of cancer are also risk factors for CRC.

[Incidence of Colon Cancer Related to Cigarette Smoking and Alcohol Consumption in Adults with Metabolic Syndrome: Prospective Cohort Study]

PURPOSE

The purpose of this study was to identify the impact of cigarette smoking and alcohol consumption on the incidence of colon cancer in adults with metabolic syndrome.

METHODS

This study employed a longitudinal study design and utilized secondary data drawn from the Korean Genome and Epidemiology Study (KoGES). The data of a sample of 2,327 adults with metabolic syndrome tracked every two years from 2001 to 2014 were used in this study. Statistical data analyses of the frequency, number of cases per 100,000 person-years, log-rank test, Kaplan-Meier curve, and Cox's proportional hazards regression were performed using IBM SPSS statistics version 24.

RESULTS

During the observation period, the number of colon cancer cases was 46, and the total person-years were 252,444. The incidence of colon cancer was higher in current, over 10 pack-year smokers when compared to non-smokers (hazard ratio=3.38, 95% confidence interval=1.09~8.42).

CONCLUSION

Excessive and long-term smoking should be avoided to prevent colon cancer, especially in adults with metabolic syndrome, since it might exacerbate the risk factors of colon cancer. Particularly, health professionals need to provide individualized smoking cessation interventions to those at high risk of colon cancer.

Association of genetic polymorphisms in PTEN and additional interaction with alcohol consumption and smoking on colorectal cancer in Chinese population

AIMS

To investigate the association of phosphatase and tensin homologue deleted on chromosome ten (PTEN) gene rs3830675, and additional interaction with drinking and smoking on colorectal cancer (CRC), based on a hospital based Chinese case-control study.

METHODS

A total of 850 subjects (413 males and 437 females) were studied, including 422 colorectal cancer cases and 428 controls. Rs3830675 was selected for genotyping in the case-control study. Logistic regression model was used to examine the association between rs3830675 and colorectal cancer, and additional interaction with alcohol consumption and smoking.

RESULTS

The frequencies for rs3830675 (-) alleles was higher in cases than that in controls, (-) allele of rs3830675 was 24.4% in controls and 29.4% in CRC subjects (p=0.005). Logistic analysis showed that the carriers of (-) allele of rs3830675 revealed increased CRC risk than those with (+/+) genotype, adjusted OR (95% CI) was 1.35(1.12-1.98). We found a significant interaction between alcohol consumption and rs3830675, drinkers with (-/-) or (-/+) of rs3830675 genotype have highest colorectal cancer risk, compared to never drinking subjects with (+/+) genotype, OR (95% CI) was 2.57 (1.66-3.33), after covariates adjustment. In addition, we also found that smokers with (-/-) or (-/+) of rs3830675 genotype have highest colorectal cancer risk, compared to never smokers with (+/+) genotype, OR (95% CI) was 3.01 (1.58-6.05).

CONCLUSIONS

The (-) allele of rs3830675 was positively with colorectal cancer risk. There was a significant role of interaction of rs3830675 with alcohol consumption and smoking on colorectal cancer.

Comparison in dietary patterns derived for the Canadian Newfoundland and Labrador population through two time-separated studies

Background

While a dietary pattern is often believed to be stable in a population, there is limited research assessing its stability over time. The objective of this study is to explore and compare major dietary patterns derived for the Canadian subpopulation residing in Newfoundland and Labrador (NL), through two time-separated studies using an identical method.

Methods

In this study, we derived and compared the major dietary patterns derived from two independent studies in the NL adult population. The first study was based on the healthy controls from a large population-based case–control study (CCS) in 2005. The second was from a food-frequency questionnaire validation project (FFQVP) conducted in 2012. In both studies, participants were recruited in the same manner and dietary information was collected by an identical self-administered food-frequency questionnaire (FFQ). Exploratory common factor analysis was conducted to identify major dietary patterns. A comparison was conducted between the two study populations.

Results

Four major dietary patterns were identified: Meat, Vegetables/fruits, Fish, and Grains explaining 22 %, 20 %, 12 % and 9 % variance respectively, with a total variance of 63 %. Three major dietary patterns were derived for the controls of the CCS: Meat, Plant-based diet, and Fish explaining 24 %, 20 %, and 10 % variance respectively, with a total variance of 54 %. As the Plant-based diet pattern derived for the CCS was a combination of the Vegetables/fruits and Grains patterns derived for the FFQVP, no considerable difference in dietary patterns was found between the two studies.

Conclusion

A comparison between two time-separated studies suggests that dietary patterns of the NL adult population have remained reasonably stable over almost a decade.

Nomogram prediction of metachronous colorectal neoplasms in patients with colorectal cancer

OBJECTIVE

To construct a predictive model of postoperative colorectal neoplasm development using a nomogram.

BACKGROUND

Although patients with colorectal cancer (CRC) are known to be at high risk of developing metachronous adenoma or CRC, no statistical model for predicting the incidence of postoperative colorectal lesions has been reported.

METHODS

A total of 309 CRC patients who underwent surgical resection received regular endoscopic follow-up to detect the development of metachronous adenoma or adenocarcinoma. The patients were divided into the derivation set (n = 209) and the validation set (n = 100). The nomogram to predict the 3- and 5-year adenoma-free survival rates was constructed using the derivation set, and a calibration plot and concordance index (c-index) were calculated. The predictive utility of the nomogram was validated in the validation set.

RESULTS

Sex, age, and number of synchronous lesions at the time of surgery for primary CRC were adopted as variables for the nomogram. The nomogram showed moderate calibration, with a c-index of 0.709 in the derivation set and 0.712 in the validation set.

CONCLUSIONS

A nomogram based on sex, age, and number of synchronous lesions at the time of surgery has the ability to predict postoperative adenoma-free survival.

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.

Influence of pre-diagnostic cigarette smoking on colorectal cancer survival: overall and by tumour molecular phenotype

BACKGROUND

Smoking is a risk factor for incident colorectal cancer (CRC); however, it is unclear about its influence on survival after CRC diagnosis.

METHODS

A cohort of 706 CRC patients diagnosed from 1999 to 2003 in Newfoundland and Labrador, Canada, was followed for mortality and recurrence until April 2010. Smoking and other relevant data were collected by questionnaire after cancer diagnosis, using a referent period of '2 years before diagnosis' to capture pre-diagnosis information. Molecular analyses of microsatellite instability (MSI) status and BRAF V600E mutation status were performed in tumour tissue using standard techniques. Multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated with Cox proportional hazards regression, controlling for major prognostic factors.

RESULTS

Compared with never smokers, all-cause mortality (overall survival, OS) was higher for current (HR: 1.78; 95% CI: 1.04-3.06), but not for former (HR: 1.06; 95% CI: 0.71-1.59) smokers. The associations of cigarette smoking with the study outcomes were higher among patients with ≥40 pack-years of smoking (OS: HR: 1.72; 95% CI: 1.03-2.85; disease-free survival (DFS: HR: 1.99; 95% CI: 1.25-3.19), those who smoked ≥30 cigarettes per day (DFS: HR: 1.80; 95% CI: 1.22-2.67), and those with microsatellite stable (MSS) or MSI-low tumours (OS: HR: 1.38; 95% CI: 1.04-1.82 and DFS: HR: 1.32; 95% CI: 1.01-1.72). Potential heterogeneity was noted for sex (DFS HR: 1.68 for men and 1.01 for women: P for heterogeneity=0.04), and age at diagnosis (OS: HR: 1.11 for patients aged <60 and 1.69 for patients aged ≥60: P for heterogeneity=0.03).

CONCLUSIONS

Pre-diagnosis cigarette smoking is associated with worsened prognosis among patients with CRC.

Dietary N-nitroso compounds and risk of colorectal cancer: a case-control study in Newfoundland and Labrador and Ontario, Canada

Several N-nitroso compounds (NOC) have been shown to be carcinogenic in a variety of laboratory animals, but evidence of their carcinogenicity in humans is lacking. We aimed to examine the association between NOC intake and colorectal cancer (CRC) risk and possible effect modification by vitamins C and E and protein in a large case-control study carried out in Newfoundland and Labrador and Ontario, Canada. A total of 1760 case patients with pathologically confirmed adenocarcinoma and 2481 population controls were asked to complete a self-administered FFQ to evaluate their dietary intakes 1 year before diagnosis (for cases) or interview (for controls). Adjusted OR and 95 % CI were calculated across the quintiles of NOC (measured by N-nitrosodimethylamine (NDMA)) intake and relevant food items using unconditional logistic regression. NDMA intake was found to be associated with a higher risk of CRC (highest v. lowest quintiles: OR 1·42, 95 % CI 1·03, 1·96; P for trend = 0·005), specifically for rectal carcinoma (OR 1·61, 95 % CI 1·11, 2·35; P for trend = 0·01). CRC risk also increased with the consumption of NDMA-containing meats when the highest tertile was compared with the lowest tertile (OR 1·47, 95 % CI 1·03, 2·10; P for trend = 0·20). There was evidence of effect modification between dietary vitamin E and NDMA. Individuals with high NDMA and low vitamin E intakes had a significantly increased risk than those with both low NDMA and low vitamin E intakes (OR 3·01, 95 % CI 1·43, 6·51; P for interaction = 0·017). The present results support the hypothesis that NOC intake may be positively associated with CRC risk in humans. Vitamin E, which inhibits nitrosation, could modify the effect of NDMA on CRC risk.

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.

Associations between lifestyles and neutrophil-lymphocyte and platelet-lymphocyte ratios in colorectal cancer

AIMS

To explore the etiology of the neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) abnormalities in colorectal cancer.

METHODS

In total, 230 patients with histopathologically confirmed colorectal cancer from August 2009 to August 2011 were recruited to our study. The associations between lifestyles (smoking, alcohol and pickled food consumption) and pretreatment NLR and PLR were estimated using the Kruskal-Wallis tests and linear regression model.

RESULTS

The Kruskal-Wallis test showed a significant association between pickled food intake and pretreatment NLR but not PLR (P = 0.002, 0.057, respectively). Pairwise comparisons showed that, compared with those with a moderately frequent (2-3 times/week) and an infrequent (≤ once a week) intake of pickled food, high frequency (≥ four times/week) consumption of pickled food had a higher pretreatment NLR (P = 0.01, 0.007, respectively). Multivariate linear regression analysis showed pretreatment NLR increased significantly in high frequency (≥ four times/week) consumption of pickled food (P < 0.0001). No association between other lifestyle factors and pretreatment PLR was found.

CONCLUSIONS

A higher frequency intake of pickled food possibly contributes to higher NLR, which may reflect a systemic inflammatory response in colorectal cancer.

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.

Diabetes and sex-specific colorectal cancer risks in Newfoundland and Labrador: a population-based retrospective cohort study

OBJECTIVE

Studies on the relationship between diabetes and colorectal cancer (CRC) are inconsistent. It is also unclear whether CRC risk elevation for individuals with diabetes is similar for males and females. Using data from Newfoundland and Labrador (NL), the province with the highest CRC incidence and diabetes prevalence in Canada, we assessed and compared the risk elevation of CRC for males and females with diabetes, overall and by anatomic subsite.

METHODS

A population-based retrospective cohort study including a study sample of 122,228 individuals aged ≥30 years was conducted using administrative health databases over a 10.5-year period (October 1, 1996 to March 31, 2007). Hazard ratios were estimated using Cox proportional hazard models.

RESULTS

In comparison with non-diabetes counterparts, both males and females with diabetes were at a significantly elevated risk of overall CRC, with corresponding hazard ratios of 1.38 and 1.52, respectively. For males, diabetes significantly increased the risk of proximal and distal colon cancers, but not of rectal cancer. For females, diabetes significantly increased the risk of proximal colon and rectal cancers, but not of distal colon cancer. The results suggest that there is a stronger association between diabetes and CRC for females than for males, and the association did not change after adjusting for overweight/obesity.

CONCLUSIONS

Diabetes led to a greater risk of CRC in both the male and female population in NL. Risk was subsite-specific and varied by sex. Future research should examine reasons for the observed diabetes-associated CRC risk to support CRC prevention strategies among the diabetes population.

Polyp surveillance after surgery for colorectal cancer

PURPOSE

Although it is known that those patients who have developed colorectal cancer (CRC) are at a higher risk to develop metachronous adenoma or CRC, no study has been performed to analyze the relationship between the risk factors and the time course for the formation of postoperative adenoma using survival analysis.

METHODS

One hundred seventy-six patients with CRC,who had received surgical resection, were endoscopically followed-up to detect the development of metachronous adenoma or adenocarcinoama. The association between the risk factors such as age, synchronous adenomas with index CRC or other clinicopathological variables and the formation of postoperative adenoma was assessed using the logrank test and the Cox proportional hazard model.

RESULTS

Age over 60, synchronous lesions at the time of surgery for primary CRCs and presence of diabetes mellitus(DM) as the associated disease were positively related to the formation of postoperative adenoma. Among those patients with the three risk factors, only 27.8% remained adenoma-free during 5 years after operation, whereas in the group without any risk factor, it was 90.4%.

CONCLUSIONS

From our data, age over 60, synchronous adenomas or CRCs and DM were the potential risk factors for the postoperative formation of adenoma or CRC, and they should be taken into consideration when defining the appropriate interval of postoperative colonoscopy.

Association of total energy intake and macronutrient consumption with colorectal cancer risk: results from a large population-based case-control study in Newfoundland and Labrador and Ontario, Canada

Background

Diet is regarded as one of the most important environmental factors associated with colorectal cancer (CRC) risk. A recent report comprehensively concluded that total energy intake does not have a simple relationship with CRC risk, and that the data were inconsistent for carbohydrate, cholesterol and protein. The objective of this study was to identify the associations of CRC risk with dietary intakes of total energy, protein, fat, carbohydrate, fiber, and alcohol using data from a large case-control study conducted in Newfoundland and Labrador (NL) and Ontario (ON), Canada.

Methods

Incident colorectal cancer cases (n = 1760) were identified from population-based cancer registries in the provinces of ON (1997-2000) and NL (1999-2003). Controls (n = 2481) were a random sample of residents in each province, aged 20-74 years. Family history questionnaire (FHQ), personal history questionnaire (PHQ), and food frequency questionnaire (FFQ) were used to collect study data. Logistic regression was used to evaluate the association of intakes of total energy, macronutrients and alcohol with CRC risk.

Results

Total energy intake was associated with higher risk of CRC (OR: 1.56; 95% CI: 1.21-2.01, p-trend = 0.02, 5^th versus 1^st quintile), whereas inverse associations emerged for intakes of protein (OR: 0.85, 95%CI: 0.69-1.00, p-trend = 0.06, 5^th versus 1^st quintile), carbohydrate (OR: 0.81, 95%CI: 0.63-1.00, p-trend = 0.05, 5^th versus 1^st quintile) and total dietary fiber (OR: 0.84, 95% CI:0.67-0.99, p-trend = 0.04, 5^th versus 1^st quintile). Total fat, alcohol, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, and cholesterol were not associated with CRC risk.

Conclusion

This study provides further evidence that high energy intake may increase risk of incident CRC, whereas diets high in protein, fiber, and carbohydrate may reduce the risk of the disease.

Interaction between alcohol drinking and obesity in relation to colorectal cancer risk: a case-control study in Newfoundland and Labrador, Canada

Background

While substantive epidemiological literature suggests that alcohol drinking and obesity are potential risk factors of colorectal cancer (CRC), the possible interaction between the two has not been adequately explored. We used a case-control study to examine if alcohol drinking is associated with an increased risk of CRC and if such risk differs in people with and without obesity.

Methods

Newly diagnosed CRC cases were identified between 1999 and 2003 in Newfoundland and Labrador (NL). Cases were frequency-matched by age and sex with controls selected using random digit dialing. Cases (702) and controls (717) completed self-administered questionnaires assessing health and lifestyle variables. Estimates of alcohol intake included types of beverage, years of drinking, and average number of alcohol drinks per day. Odds ratios were estimated to investigate the associations of alcohol independently and when stratified by obesity status on the risk of CRC.

Results

Among obese participants (BMI ≥ 30), alcohol was associated with higher risk of CRC (OR: 2.2; 95% CI: 1.2-4.0) relative to the non-alcohol category. Among obese individuals, 3 or more different types of drinks were associated with a 3.4-fold higher risk of CRC relative to non-drinkers. The risk of CRC also increased with drinking years and drinks daily among obese participants. However, no increased risk was observed in people without obesity.

Conclusion

The effect of alcohol of drinking on CRC seems to be modified by obesity.

Prevalence and distribution of adenomas in black Americans undergoing colorectal cancer screening

BACKGROUND

The American College of Gastroenterology recommends colorectal cancer (CRC) screening for average-risk black Americans ages 45-49. This is based on this group's younger age for the development of adenomas and CRC. Our purpose was to determine the yield of CRC screening in average-risk black Americans including those <age 50. We also aimed to identify whether there was a higher prevalence of proximal adenomas in black Americans.

STUDY

This was a cross-sectional, retrospective study. All colonoscopy examinations from 2007 through 2010 were reviewed. Complete examinations with a good/excellent preparation in average-risk black patients 45-49 were selected. We excluded patients with signs, symptoms, or family history of CRC. Defined two control groups: average-risk black and white patients ages 50-59 who completed a colonoscopy during the same period. Patient's height, weight, and use of statin medications and aspirin were recorded. Patients currently using tobacco at least weekly were identified.

RESULTS

There were 1,230 patients with an adenoma for a prevalence of 40.7%. We included 304 black Americans 45-49 years, 669 black Americans 50-59 years, and 257 whites 50-59 years. There was no association between race/age group and the presence of at least one adenoma, proximal adenomas, or advanced adenomas. In regression modeling, both male sex and active smoking were associated with all three outcomes.

CONCLUSIONS

Male sex and active smoking are risk factors for prevalent adenomas, proximal adenomas, and advanced adenomas. The prevalence of adenomas is similar in black Americans 45-49 compared to older black and white patients. We did not find that the recognized proximal distribution of CRC in black Americans parallels a similar distribution in adenomas in this group.

Calcium and vitamin D and risk of colorectal cancer: results from a large population-based case-control study in Newfoundland and Labrador and Ontario

BACKGROUND

Previous epidemiological studies have been suggestive but inconclusive in demonstrating inverse associations of calcium, vitamin D, dairy product intakes with risk of colorectal cancer (CRC). We conducted a large population-based comparison of such associations in Newfoundland and Labrador (NL) and Ontario (ON).

METHODS

A case control study design was used. Colorectal cancer cases were new CRC patients aged 20-74 years. Controls were a sex and age-group matched random sample of the population in each province. 1760 cases and 2481 controls from NL and ON were analyzed. Information on dietary intake and lifestyle was collected using self-administered food frequency and personal history questionnaires.

RESULTS

Controls reported higher mean daily intakes of total calcium and total vitamin D than cases in both provinces. In ON, significant reduced CRC risk was associated with intakes of total calcium (OR of highest vs. lowest quintiles was 0.57, 95% CI 0.42-0.77, p(trend) = 0.03), total vitamin D (OR = 0.73, 95% CI 0.54-1.00), dietary calcium (OR = 0.76, 95% CI 0.60-0.97), dietary vitamin D (OR = 0.77, 95% CI 0.61-0.99), total dairy products and milk (OR = 0.78, 95% CI 0.60-1.00), calcium-containing supplements use (OR = 0.76). In NL, the inverse associations of calcium, vitamin D with CRC risk were most pronounced among calcium- or vitamin D-containing supplement users (OR = 0.67, 0.68, respectively).

CONCLUSIONS

Results of this study add to the evidence that total calcium, dietary calcium, total vitamin D, dietary vitamin D, calcium- or vitamin D-containing supplement use may reduce the risk of CRC. The inverse associations of CRC risk with intakes of total dairy products and milk may be largely due to calcium and vitamin D.