Increasing incidence in liver cancer in Canada, 1972-2006: Age-period-cohort analysis

BACKGROUND/AIMS

Our study aimed to assess 1) the temporal trends in incidence and mortality of liver cancer and 2) age-period-cohort effects on the incidence in Canada.

METHODS

We analyzed data obtained from the Canadian Cancer Registry Database and Canadian Vital Statistics Death Database. We first examined temporal trends by sex, age group, and birth cohort between 1972 and 2006. Three-year period rates and annual percentage change (APC) were calculated to compare the changes over the study period. We used age-period-cohort modelling to estimate underlying effects on the observed trends in incidence.

RESULTS

The overall age-adjusted incidence rates increased from 2.6 and 1.5 per 100 000 in 1972-74 to 6.5 (APC: 2.9) and 2.2 (APC: 1.2) per 100 000 in 2004-06 among males and females, respectively. The age-adjusted mortality rates increased from 3.3 and 2.0 per 100 000 in 1972-74 to 6.0 (APC: 2.3) and 2.6 (APC: 1.2) per 100 000 in 2004-06 among males and females, respectively. The incidence increased most rapidly in men aged 45-54 years (APC: 4.1) and women aged 65-74 years (APC: 1.7) over the period of study.

CONCLUSIONS

The age-period-cohort analysis suggests that birth-cohort effect is underlying the increase in incidence. While the exact reason for the increased incidence of liver cancer remains unknown, reported increase in HBV and HCV infections, and immigration from high-risk regions of the world may be important factors.

Antioxidants and breast cancer risk- a population-based case-control study in Canada

BACKGROUND

The effect of antioxidants on breast cancer is still controversial. Our objective was to assess the association between antioxidants and breast cancer risk in a large population-based case-control study.

METHODS

The study population included 2,362 cases with pathologically confirmed incident breast cancer (866 premenopausal and 1,496 postmenopausal) and 2,462 controls in Canada. Intakes of antioxidants from diet and from supplementation as well as other potential risk factors for breast cancer were collected by a self-reported questionnaire.

RESULTS

Compared with subjects with no supplementation, 10 years or longer supplementation of zinc had multivariable-adjusted odds ratios (OR) and 95% confidence intervals (CI) of 0.46 (0.25-0.85) for premenopausal women, while supplementation of 10 years or longer of multiple vitamin, beta-carotene, vitamin C, vitamin E and zinc had multivariable-adjusted ORs (95% CIs) of 0.74 (0.59, 0.92), 0.58 (0.36, 0.95), 0.79 (0.63-0.99), 0.75 (0.58, 0.97), and 0.47 (0.28-0.78), respectively, for postmenopausal women. No significant effect of antioxidants from dietary sources (including beta-carotene, alpha-carotene, lycopene, lutein and zeaxanthin, vitamin C, vitamin E, selenium and zinc) or from supplementation less than 10 years was observed.

CONCLUSIONS

This study suggests that supplementation of zinc in premenopausal women, and supplementation of multiple vitamin, beta-carotene, vitamin C, vitamin E and zinc in postmenopausal women for 10 or more years may protect women from developing breast cancer. However, we were unable to determine the overall effect of total dose or intake from both diet and supplement.

Dietary cholesterol intake and cancer

BACKGROUND

This study assesses the association between dietary cholesterol intake and the risk of various cancers.

PATIENTS AND METHODS

Mailed questionnaires were completed between 1994 and 1997 in eight Canadian provinces by 1182 incident histologically confirmed cases of the stomach, 1727 of the colon, 1447 of the rectum, 628 of the pancreas, 3341 of the lung, 2362 of the breast, 442 of the ovary, 1799 of the prostate, 686 of the testis, 1345 of the kidney, 1029 of the bladder, 1009 of the brain, 1666 non-Hodgkin's lymphomas (NHL), 1069 leukemia and 5039 population controls. Information on dietary habits and nutrition intake were obtained using a food frequency questionnaire, which provided data on eating habits 2 years before the study. Odds ratios (ORs) were derived by unconditional logistic regression to adjust for total energy intake and other potential confounding factors.

RESULTS

Dietary cholesterol was positively associated with the risk of cancers of the stomach, colon, rectum, pancreas, lung, breast (mainly postmenopausal), kidney, bladder and NHL: the ORs for the highest versus the lowest quartile ranged from 1.4 to 1.7. In contrast, cholesterol intake was inversely associated with prostate cancer.

CONCLUSIONS

Our findings add to the evidence that high cholesterol intake is linked to increased risk of various cancers. A diet low in cholesterol may play a role in the prevention of several cancers.

Epidemiology of cancer of the small intestine

Cancer of the small intestine is very uncommon. There are 4 main histological subtypes: adenocarcinomas, carcinoid tumors, lymphoma and sarcoma. The incidence of small intestine cancer has increased over the past several decades with a four-fold increase for carcinoid tumors, less dramatic rises for adenocarcinoma and lymphoma and stable sarcoma rates. Very little is known about its etiology. An increased risk has been noted for individuals with Crohn’s disease, celiac disease, adenoma, familial adenomatous polyposis and Peutz-Jeghers syndrome. Several behavioral risk factors including consumption of red or smoked meat, saturated fat, obesity and smoking have been suggested. The prognosis for carcinomas of the small intestine cancer is poor (5 years relative survival < 30%), better for lymphomas and sarcomas, and best for carcinoid tumors. There has been no significant change in long-term survival rates for any of the 4 histological subtypes. Currently, with the possible exceptions of obesity and cigarette smoking, there are no established modifiable risk factors which might provide the foundation for a prevention program aimed at reducing the incidence and mortality of cancers of the small intestine. More research with better quality and sufficient statistical power is needed to get better understanding of the etiology and biology of this cancer. In addition, more studies should be done to assess not only exposures of interest, but also host susceptibility.

Dietary sodium intake among Canadian adults with and without hypertension

Introduction

Almost 30% of hypertension among Canadians may be attributed to excess dietary sodium.

Methods

We examined the average sodium intake of Canadians aged 30 years and over, with and without hypertension, by age, sex and diabetes status using 24-hour recall data from the 2004 Canadian Community Health Survey, Cycle 2.2, Nutrition. We compared absolute (crude) average sodium intake levels of those with and without hypertension to the 2009 Canadian Hypertension Education Program (CHEP) guidelines and adjusted average sodium intake between those with and without hypertension.

Results

Both those with and without diagnosed hypertension display average sodium intakes well above the 1500 mg/day recommended by the 2009 CHEP guidelines (2950 mg/day and 3175 mg/day, respectively). After confounding adjustment, those with hypertension have significantly higher average sodium intake (p = .0124). Stratified subgroup analyses found the average sodium intake among those with hypertension was higher for men between 30 and 49 years old (p = .0265), women between 50 and 69 years old (p = .0083) and those without diabetes (p = .0071) when compared to their counterparts without hypertension.

Conclusion

Better approaches are needed to reduce sodium intake in hypertension patients, as well as the general population.

Dietary sodium intake among Canadian adults with and without hypertension

INTRODUCTION

Almost 30% of hypertension among Canadians may be attributed to excess dietary sodium.

METHODS

We examined the average sodium intake of Canadians aged 30 years and over, with and without hypertension, by age, sex and diabetes status using 24-hour recall data from the 2004 Canadian Community Health Survey, Cycle 2.2, Nutrition. We compared absolute (crude) average sodium intake levels of those with and without hypertension to the 2009 Canadian Hypertension Education Program (CHEP) guidelines and adjusted average sodium intake between those with and without hypertension.

RESULTS

Both those with and without diagnosed hypertension display average sodium intakes well above the 1500 mg/day recommended by the 2009 CHEP guidelines (2950 mg/day and 3175 mg/day, respectively). After confounding adjustment, those with hypertension have significantly higher average sodium intake (p = .0124). Stratified subgroup analyses found the average sodium intake among those with hypertension was higher for men between 30 and 49 years old (p = .0265), women between 50 and 69 years old (p = .0083) and those without diabetes (p = .0071) when compared to their counterparts without hypertension.

CONCLUSION

Better approaches are needed to reduce sodium intake in hypertension patients, as well as the general population.

Evaluation of multiplex ligation-dependent probe amplification as a method for the detection of copy number abnormalities in B-cell precursor acute lymphoblastic leukemia

Recent genomic studies have shown that copy number abnormalities (CNA) of genes involved in lymphoid differentiation and cell cycle control are common in B-cell precursor acute lymphoblastic leukemia (BCP-ALL). We have evaluated Multiplex Ligation-dependent Probe Amplification (MLPA) on 43 BCP-ALL patients for the detection of the most common deletions among these genes and compared the results to those obtained by fluorescence in situ hybridization (FISH) and genomic quantitative PCR (qPCR). There was good correlation between methods for CDKN2A/B, IKZF1, and PAX5 deletions in the majority of cases and MLPA confirmed the presence of deletions within the PAR1 region in two of three cases identified by FISH. Small intragenic aberrations detected by MLPA, which were below the resolution of FISH for CDKN2A/B (n = 7), IKZF1 (n = 3), and PAX5 (n = 3) were confirmed by qPCR. MLPA and qPCR were unable to detect populations present at a low level (<20%) by FISH. In addition, although MLPA identified the presence of a deletion, it was unable to discern the presence of mixed cell populations which had been identified by FISH: CDKN2A/B (n = 3), IKZF1 (n = 1), PAX5 (n = 2), and PAR1 deletion (n = 1). Nevertheless, this study has demonstrated that MLPA is a robust technique for the reliable detection of CNA involving multiple targets in a single test and thus is ideal for rapid high throughput testing of large cohorts with a view to establishing incidence and prognostic significance.

Breast cancer incidence and hormone replacement therapy in Canada

BACKGROUND

In 2002, results of the Women's Health Initiative clinical trial indicated that the long-term risks of combined estrogen and progestin hormone replacement therapy outweighed the health benefits for postmenopausal women. The resulting decline in use of hormone replacement therapy was followed by concurrent decreases in breast cancer incidence in several countries. The aim of the current study was to determine whether similar declines occurred in Canada.

METHODS

Data on prescriptions for hormone therapy were obtained from a national registry of pharmacy-filled prescriptions to confirm the reported trend in use of hormone replacement therapy among approximately 1200 women aged 50-69 years who participated in the National Population Health Survey between 1996 and 2006 and whose data were extrapolated to the Canadian female population. Age-standardized incidence rates for breast cancer were obtained from the population-based Canadian Cancer Registry for the same period, and mammography rates were obtained from the Canadian Community Health Survey. Joinpoint regression was used to examine changes in trends in the use of hormone replacement therapy and breast cancer incidence.

RESULTS

A reduced frequency of use of hormone replacement therapy was reflected in the decrease in dispensed hormone therapy prescriptions after 2002. The largest drop in use of combined hormone replacement therapy (from 12.7%, 95% confidence interval [CI] = 10.1% to 14.2%, to 4.9%, 95% CI = 3.4% to 6.8%, of all women) occurred between January 1, 2002, and December 31, 2004, among women aged 50-69 years. This drop occurred concurrently with a 9.6% decline in the incidence rate of breast cancer (from 296.3 per 100,000 women, 95% CI = 290.8 to 300.5 per 100,000 women, in 2002 to 268.0 per 100,000 women, 95% CI = 263.3 to 273.5 per 100,000 women, in 2004). Mammography rates were stable at 72% over the same period.

CONCLUSION

During the period 2002-2004, there was a link between the declines in the use of hormone replacement therapy and breast cancer incidence among Canadian women aged 50-69 years, in the absence of any change in mammography rates.

Physical activity and hematologic cancer prevention

This chapter presents the epidemiologic evidence on the association between physical activity and hematologic cancers and related hypothesized biologic mechanisms. Some preliminary indications of a protective role for physical activity for non-Hodgkin's lymphoma, leukemia, multiple myeloma, and Hodgkin's lymphoma exist, but the level of epidemiologic evidence is still insufficient to make any definitive conclusions regarding the nature of these associations. Several plausible biologic mechanisms underlying the possible associations between physical activity and hematologic cancers have been proposed, including enhancement of immune function, reduction in obesity, improvement of antioxidant defense systems, impact on metabolic hormones, and anti-inflammatory effects. Future studies should improve the estimation of physical activity by using more reliable, valid, and comprehensive measurement tools, assessing all components of physical activity (type, intensity, and time period), and conducting intervention studies to evaluate the effect of physical activity on various biomarkers of cancer in order to provide further insight into plausible biologic mechanisms underlying the possible association between physical activity and hematologic cancers.

Statin use in Canadians: trends, determinants and persistence

BACKGROUND

Regular statin use is an important tool in chronic disease management, lowering cholesterol levels and reducing risk of cardiovascular disease (CVD). The objectives of this study are to describe statin use in Canada by comorbidity and lifestyle risk factors, and determine persistence in statin use.

METHODS

The longitudinal National Population Health Survey, 1994-2002, is a random sample of the 1994 Canadian population and five interviews were conducted at two-year intervals. A total of 8,198 respondents, aged 20 in 1994, completed all five interviews. Information collected included demographic variables, medication use, CVD lifestyle risk factors, CVD, diabetes and hypertension.

RESULTS

Age-adjusted rates of statin use increased from 1.6% to 7.8% over the period 1994-2002. Statin use was higher with increasing age, diabetes, BMI, physician visits, and insurance for prescription medication. Although persons with CVD were more likely to take statins than those without, by 2002 still only 32.7% of heart patients were taking statins. Statin use did not increase linearly with increasing numbers of CVD risk factors or comorbidities. Of the 441 persons reporting statin use in 2000, 74.6% were still taking them in 2002. People who completed their high school education were more likely to continue taking statins than those who did not complete high school.

CONCLUSION

While statin use increased over time, was associated with CVD and diabetes, and to a lesser extent with increased BMI, a substantive underuse in high-risk patients remains. Helping high-risk people to increase statin use continues to be a priority for health care professionals.

Diet and vitamin or mineral supplementation and risk of colon cancer by subsite in Canada

The study assesses the association of diet and vitamin or mineral supplementation with risk of proximal or distal colon cancer. Mailed questionnaires were completed by 1723 newly diagnosed, histologically confirmed colon cancer cases and 3097 population controls between 1994 and 1997 in seven Canadian provinces. Measurement included information on socio-economic status, physical activity, smoking habits, alcohol use, diet and vitamin or mineral supplementation. Odds ratios and 95% confidence intervals were derived through unconditional logistic regression. Linear regression was used to examine that dietary factors affect body mass index. The strongest positive associations between colon cancer risk and increasing total fat intake were observed for proximal colon cancer in men and for distal colon cancer in both men and women. Increased consumption of vegetables, fruit and whole-grain products did not reduce the risk of colon cancer. A modest reduction in distal colon cancer risk was noted in women who consumed yellow-orange vegetables. Significant positive associations were observed between proximal colon cancer risk in men and consumption of red meat and dairy products, and between distal colon cancer risk in women and total intake of meat and processed meat. We also saw strong associations between bacon intake and both subsites of colon cancer in women. When men were compared with women directly by subsite however, the results did not show a corresponding association. A significantly reduced risk of distal colon cancer was noted in women only with increasing intake of dairy products and of milk. Among men and women taking vitamin and mineral supplements for more than 5 years, significant inverse associations with colon cancer were most pronounced among women with distal colon cancer. These findings suggest that dietary risk factors for proximal colon cancer may differ from those for distal colon cancer.

Quantifying the impact of obesity category on major chronic diseases in Canada

Adverse health effects differ with various levels of obesity, but limited national data existed previously for the Canadian population. We examined the associations of sociodemographic and behavioral factors with obesity levels in Canada, and measured the impact of each level on major chronic diseases. Data were extracted from the 2003 Canadian Community Health Survey. We grouped overweight/obese participants aged 18 years and over into four levels based on body mass index (BMI, kg/m²): overweight (25.0– 29.9), class I obesity (30.0–34.9), class II obesity (35–39.9), and class III obesity (extreme/clinical obesity, BMI ≥ 40.0). We used logistic regression models to identify potential risk factors for the obesity levels and to estimate adjusted odds ratios (ORs) for major chronic diseases related to each level. We calculated population attributable risks (PARs) to help understand the impact of obesity levels on these chronic diseases.

The overall prevalence of obesity was 16.2% in men and 14.6% in women, and the prevalence of obesity III was 1.0% in men and 1.4% in women. All levels of obesity increased with age, but then decreased in elderly participants. The prevalence of diabetes, hypertension, heart disease, arthritis, and asthma increased with increasing BMI level, and the highest values appeared in participants at the obesity III level. PAR was highest in the obesity III group for hypertension, followed by diabetes, and lowest for heart disease. When correlated with risk factors, fewer statistically significant ORs, comparing to the normal weight category, appeared for obesity II and III levels than for overweight and obesity I. ORs for the combination of low education level, infrequent exercise, and low household income rose significantly with BMI levels until the obesity II level, and in obesity III level, the OR remained at the same level as for obesity II, most significantly in women. These results suggest that the impact of obesity on Canadian’s health should be studied and dealt with by obesity level. The greatest impact of clinical obesity was on hypertension and diabetes control in Canada.

Adolescent injury deaths and hospitalization in Canada: magnitude and temporal trends (1979-2003)

PURPOSE

To understand the magnitude and the national trends of mortality and hospitalization due to injuries among Canadian adolescents aged 15-19 years in 1979-2003.

METHODS

Data on injury deaths and hospitalizations were obtained from the national Vital Statistical System and the Hospital Morbidity Database. Injuries were classified by intent and by mechanism.

RESULTS

In 15-19-year-olds, 75.6% of all deaths and 16.6% of all hospitalizations were attributed to injuries. Unintentional and self-inflicted injuries accounted for 70.2% and 24.1%, respectively, of total injury deaths as well as 72.6% and 17.4%, respectively, of total injury hospitalizations. The main causes for injury were motor vehicle traffic-related injury (MVT), suffocation, firearm, poisoning, and drowning for injury deaths; and MVT, poisoning, fall, struck by/against, and cut/pierce for injury hospitalizations. Mortality and hospitalization rates of total and unintentional injuries decreased substantially, whereas those of self-inflicted injuries decreased only slightly, with a small increase in females. Rates also decreased for all causes except suffocation, which showed an increasing trend. Males had higher rates for all intents and causes than females, except for self-inflicted injury hospitalization (higher in females). The territories and Prairie Provinces also had higher ones of total injuries and self-inflicted injuries than in other provinces.

CONCLUSIONS

Injury is the leading cause of deaths and a major source of hospitalizations in Canadian adolescents. However, prevention programs in Canada have made significant progress in reducing injury mortality and hospitalization. The graduated driver licensing, enforcement of seat-belt use, speed limit and alcohol control, and Canadian tough gun control may have contributed to the decline.

The burden of adult obesity in Canada

Obesity is a major public health problem associated with a wide range of health problems. This study estimates the prevalence of obesity, calculates the proportion (or population-attributable fraction [PAF]) of major chronic diseases which is attributable to obesity, estimates the deaths attributable to it and projects its future prevalence trends. In Canada, the overall age-standardized prevalence proportion of obesity has increased from 10 percent in 1970 to 23% in 2004 (8 percent to 23 percent in men and 13 percent to 22 percent in women). The increasing prevalence of obesity was observed for all five age groups examined: 20-34, 35-44, 45-54, 55-64 and 65+. On average, the PAF of prevalence of selected major chronic diseases which is attributable to obesity from 1970 to 2004 has increased by 138 percent for men and by 60 percent for women. Overall, in 2004, 45 percent of hypertension, 39 percent of type II diabetes, 35 percent of gallbladder disease, 23 percent of coronary artery diseases (CAD), 19 percent of osteoarthritis, 11 percent of stroke, 22 percent of endometrial cancer, 12 percent of postmenopausal breast cancer, and 10 percent of colon cancer could be attributed to obesity. In 2004, 8,414 (95 percent CI: 6,881-9,927) deaths were attributable to obesity. If current obesity prevalence trends remain unchanged, the prevalence proportion of obesity in Canada is projected to reach 27 percent in men and 24 percent in women by the year 2010. These increases will have a profound impact on the treatment needs and prevalence of a wide variety of chronic diseases, and also on the health care system in terms of capacity issues and resource allocation.

Obesity, High Energy Intake, Lack of Physical Activity, and the Risk of Kidney Cancer

The authors conducted a population-based case-control study of 810 cases with histologically confirmed incident kidney cancer and 3,106 controls to assess the effect of obesity, energy intake, and recreational physical activity on renal cell and non-renal cell cancer risk in Canada from 1994 to 1997. Compared with normal body mass index (BMI; 18.5 to <25.0 kg/m2), obesity (BMI, >or=30.0 kg/m2) was associated with multivariable-adjusted odds ratios (OR) and 95% confidence intervals (95% CI) of 2.57 (2.02-3.28) for renal cell cancer and 2.79 (1.70-4.60) for non-renal cell cancer. The OR (95% CI) associated with the highest quartiles of calorie intake was 1.30 (1.02-1.66) for renal cell cancer and 1.53 (0.92-2.53) for non-renal cell cancer. Compared with the lowest quartile of total recreational physical activity, the highest quartile of total activity was associated with an OR (95% CI) of 1.00 (0.78-1.28) and 0.79 (0.46-1.36) for the two subtypes. There were no apparent differences between men and women about these associations. The influence of obesity and physical activity on the risk of renal cell and non-renal cell cancer did not change by age, whereas the effect of excess energy intake was stronger among older people. No significant effect modifications of physical activity on BMI among both genders and of energy intake on BMI among men were observed, with a synergic effect of obesity and high energy intake on renal cell cancer risk found among women. This study suggests that obesity and excess energy intake are important etiologic risk factors for renal cell and non-renal cell cancer. The role of physical activity needs further investigation.