Robert Semenciw

Serum iron and risk of fatal acute myocardial infarction.

We assessed the relation of serum iron, dietary iron, and the use of iron supplements to the risk of fatal acute myocardial infarction in the Nutrition Canada Survey cohort. We found an association between serum iron and risk of fatal acute myocardial infarction, with rate ratios for males and females in the highest category of serum iron (> or = 175 micrograms per dl) of 2.18 [95% confidence intervals (CI) = 1.01-4.74] and 5.53 (95% CI = 1.69-18.12), respectively. We found no important association between risk of fatal acute myocardial infarction and either dietary iron or iron supplement use among the 9,920 participants included in this study.

Trends by anatomic site in the incidence of cutaneous malignant melanoma in Canada, 1969–93

Trends in melanoma incidence by anatomic site were examined in Canada where ascertainment of cancer has been of a high standard. The analysis included 41,239 malignant melanomas registered between 1969 and 1993 and used an age, period and cohort modeling approach. The estimated annual increase was 4.8% for males and 3.1% for females but slowed appreciably in the later years. The lifetime risk of melanoma appeared to have peaked with women born about 1934 and men born about 1944. The age-standardized rates have now stabilized for women and are expected to plateau for men in the near future. The largest relative increases occurred for the upper limbs followed by the trunk for both sexes. Comparable generation effects were observed for intermittently exposed sites but the patterns of trend differed between sites for men and women. This supports effects due to sex- and site-specific pattern of sun exposure. The evidence, for the first time, of more favorable trends among post-World War II generations is thought to reflect reduced exposure to UV rays. This may possibly be the earliest signs of the impact of primary prevention programs, particularly if UV radiation also acts as a tumor promoter.

Brain Cancer and Farming in Western Canada

A cohort study of the mortality experience (1971-1987) of male Canadian prairie farmers has been conducted. This involved linking the records of 156,242 male Alberta, Saskatchewan and Manitoba farmers identified on the 1971 Census of Agriculture and the corresponding Census of Population to mortality records. Exposure indices for individual farm operators were derived from 1971 Census of Agriculture records. Cancer histologies for brain cancer cases were obtained from the Canadian National Cancer Incidence Database and from Provincial Cancer Registries. A statistically significant association was noted between risk of dying of glioblastomas and increasing fuel/oil expenditures (test for trend p = 0.03, top quartile relative risk = 2.11, 95% confidence interval = 0.89-5.01). No significant association was found between brain cancer and either education or mother tongue. However, low income was associated with a significantly reduced risk of brain cancer mortality.

Esophageal Cancer in Canada: Trends according to Morphology and Anatomical Location

BACKGROUND Esophageal adenocarcinoma has one of the fastest rising incidence rates and one of the lowest survival rates of any cancer type in the Western world. However, in many countries, trends in esophageal cancer differ according to tumour morphology and anatomical location. In Canada, incidence and survival trends for esophageal cancer subtypes are poorly known. METHODS Cancer incidence and mortality rates were obtained from the Canadian Cancer Registry, the National Cancer Incidence Reporting System and the Canadian Vital Statistics Death databases for the period from 1986 to 2006. Observed trends (annual per cent change) and five-year relative survival ratios were estimated separately for esophageal adenocarcinoma and squamous cell carcinoma, and according to location (upper, middle, or lower one-third of the esophagus). Incidence rates were projected up to the year 2026. RESULTS Annual age-standardized incidence rates for esophageal cancer in 2004 to 2006 were 6.1 and 1.7 per 100,000 for males and females, respectively. Esophageal adenocarcinoma incidence rose by 3.9% (males) and 3.6% (females) per year for the period 1986 to 2006, with the steepest increase in the lower one-third of the esophagus (4.8% and 5.0% per year among males and females, respectively). In contrast, squamous cell carcinoma incidence declined by 3.3% (males) and 3.2% (females) per year since the early 1990s. The five-year relative survival ratio for esophageal cancer was 13% between 2004 and 2006, approximately a 3% increase since the period from 1992 to 1994. Projected incidence rates showed increases of 40% to 50% for esophageal adenocarcinoma and decreases of 30% for squamous cell carcinoma by 2026. DISCUSSION Although esophageal cancer is rare in Canada, the incidence of esophageal adenocarcinoma has doubled in the past 20 years, which may reflect the increasing prevalence of obesity and gastroesophageal reflux disease. Declines in squamous cell carcinoma may be the result of the decreases in the prevalence of smoking in Canada. Given the low survival rates and the potential for further increases in incidence, esophageal adenocarcinoma warrants close attention.

Canadian adolescents and young adults with cancer: opportunity to improve coordination and level of care

Cancers in adolescents and young adults (aged 15–29 years) represent a transition between the nonepithelial types, especially acute leukemias and embryonal tumours, that are common during childhood and the epithelial types (i.e., carcinomas) that account for most cancers in older adults. The

Multiple myeloma mortality and agricultural practices in the Prairie provinces of Canada.

A cohort study of agricultural practices and the mortality experience (1971 to 1987) of male farmers in Manitoba, Saskatchewan, and Alberta has been conducted. The census records of 156, 242 male farmers identified on the 1971 Census of Agriculture and the corresponding Census of Population were linked to mortality records through 1987. We observed associations between multiple myeloma mortality and fuel/oil expenditures (relative risk for top quartile of exposure = 1.69, 95% confidence interval = 1.08 to 2.65). No significant associations were found between multiple myeloma and herbicide use or with selected sociodemographic variables.

Short-term cancer mortality projections: A comparative study of prediction methods

This paper provides a systematic comparison of cancer mortality and incidence projection methods used at major national health agencies. These methods include Poisson regression using an age-period-cohort model as well as a simple log-linear trend, a joinpoint technique, which accounts for sharp changes, autoregressive time series and state-space models. We assess and compare the reliability of these projection methods by using Canadian cancer mortality data for 12 cancer sites at both the national and regional levels. Cancer sites were chosen to provide a wide range of mortality frequencies. We explore specific techniques for small case counts and for overall national-level projections based on regional-level data. No single method is omnibus in terms of superior performance across a wide range of cancer sites and for all sizes of populations. However, the procedures based on age-period-cohort models used by the Association of the Nordic Cancer Registries tend to provide better performance than the other methods considered. The exception is when case counts are small, where the average of the observed counts over the recent 5-year period yields better predictions.

Mortality and cancer incidence in a nickel cohort

BACKGROUND Previous studies of nickel workers have primarily noted significant early increases in lung and nasal cancers and for various types of accidents. AIMS To examine cancer incidence and mortality, concurrently, for a cohort of male nickel workers at a major nickel and copper producer in Sudbury, Ontario, Canada. METHODS From January 1964 to December 2001, nominal roll and work history information were linked to Ontario health data and mortality and cancer incidence were compared to the Ontario population. RESULTS There were 1984 (19%) deaths and 1127 (11%) incident cancers (n = 10,253). Significant elevations in mortality were observed for accidents, poisoning and violence; for possibly job-related accidents among those with <15 years since first hire [standardized mortality ratio (SMR) = 133, 95% CI: 111-158; SMR = 241, 95% CI: 159-351, respectively] and for accidents in those with > or =15 years since first hire (SMR = 123, 95% CI: 104-144). Significant elevations were also observed for accidents, poisoning and violence for those with 6 months to 14 years work experience and for lung cancer incidence and mortality for those with 15-29 years work experience (SMR = 128, 95% CI: 107-153). Incident lung cancers were significantly elevated for those hired in the 1940s and 1960s. CONCLUSIONS Significant lung cancer mortality and incidence elevations were observed for the cohort and underground workers with increased time since first hire, for those hired during early periods of operation and for those with longer durations of employment. Further aetiological study is required as occupational aetiology could not be ascertained.

Canadian trends in liver cancer: a brief clinical and epidemiologic overview

Although primary liver cancer is rare, its incidence rate has been rising quickly in Canada, more than tripling since the early 1980s. This cancer is more common in men than women, and the age-specific incidence rates in men have been increasing significantly in all age groups from 40 years of age onward. The death rate has followed a similar upward trajectory, in part because of the low 5-year survival rate of 18% in both sexes. Infection with the hepatitis B or C virus continues to be the most common risk factor, but other factors may also play a role. Risk reduction strategies, such as viral hepatitis screening, have been recommended in other countries and warrant consideration in Canada as part of a coordinated strategy of disease prevention and control.

Estimating variability for age-standardized hospital morbidity rates: a comparative study of automated methods for web-based atlas production using medical databases

Accurate interval estimation of standardized hospital morbidity rates is essential for comparing health care utilization across geographical areas or different populations. There are typically repeated hospital admissions for individuals in the population in any specific time period; hence counts of admissions may not be well modelled by standard distributions for count data based on a Poisson assumption. This leads to empirical distributions of the counts with heavier tails than the Poisson. This paper complies and reviews various approaches for interval estimation of standardized hospital morbidity rates used at health agencies and examines their suitability under a broad range of conditions. The focus here is on approaches used for automated production of rates for developing atlases, using large-scale (e.g., country-wide) medical databases. We consider parametric models which incorporate such overdispersion, including the zero-inflated Poisson, negative binomial, zero-inflated negative binomial and Poisson-inverse-Gaussian distributions. Additionally, we consider the use of robust methods based on simple moment estimators for computing the mean and variance of the distribution of the counts, and Poisson-based methods currently utilized for some published rates when patient-level data are unavailable. A simulation study is conducted to compare the different approaches. Various confidence interval construction methods are also examined. Our results indicate that the moment approach as well as confidence intervals based on a log transformation of the rate provide more accurate inference for morbidity rates than the other methods. We recommend the use of the moment approach due to its simplicity of implementation. Some cautions regarding ad hoc approaches currently in use are also provided.