Trends in incidence, mortality, and survival for kidney cancer in Canada, 1986-2007.

PURPOSE: Kidney cancer is one of the fastest rising cancers worldwide. We aimed to examine the trends in incidence, mortality, and survival for this cancer in Canada. METHODS: Incidence data for kidney cancer for 1986-2010 were from the Canadian Cancer Registry and the National Cancer Incidence Reporting System. These data were only available up to 2007 for the province of Quebec and consequently for the same year nationally, for Canada. Mortality data for 1986-2009 were from the Canadian Vital Statistics Death Database. Changes in age-standardized rates were analyzed by Joinpoint regression. Incidence rates were projected to 2025 using a Nordpred age-period-cohort model. Five-year relative survival ratios (RSR) were analyzed for 2004-2008 and earlier periods. RESULTS: Between 1986 and 2007, the age-standardized incidence rate (ASIR) per 100,000 rose from 13.4 to 17.9 in males and 7.7 to 10.3 in females. Annual increases in ASIR were greatest for age groups <65 years (males) and ≥65 years (females). The ASIRs increased significantly over time in both sexes for renal cell carcinoma (RCC) but not for other kidney cancer types. RCC rates are projected to increase until at least 2025. Mortality rates decreased only slightly in each sex since 1986 (0.4%/year in males; 0.8%/year in females). The 5-year RSR for kidney cancer was 68% but differed largely by morphology and age, and has increased slightly over time. CONCLUSIONS: The incidence rate of kidney cancer in Canada has risen since at least 1986, led largely by RCC. Increasing detection of incidental tumors, and growing obesity and hypertension rates are possible factors associated with this increase. Greater prevention of modifiable risk factors for kidney cancer is needed.

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.

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.

Cancer and the environment: Ten topics in environmental cancer epidemiology in Canada.

This Chronic Diseases in Canada supplement is a compilation of literature reviews by scientific experts. It was initiated as follow-up to the Green Plan, the federal government's environmental agenda in the 1990s. In recognizing that Canadians are concerned about the environment and its relationship to their health, this document attempts to address some of these concerns in relation to cancer by reviewing and summarizing the epidemiological literature for ten environmental exposures, and highlighting future research needs. The topics include three types of radiation exposure (ultraviolet, radon and electromagnetic (powerfrequency electromagnetic fields)), three classes of chemical exposure (organochlorines, disinfection by-products, and pesticides), two types of air pollution (environmental tobacco smoke and outdoor air pollution), and two industrial sources (pulp and paper milling, and metal mining and processing). This publication is intended to provide a base of information for researchers interested in environmental cancer epidemiology and to assist with the formulation of research priorities. The ten topics reviewed here were selected because concern about them has been expressed or because they involve known animal carcinogens. Complete elimination of exposures to carcinogens in the environment, synthetic or natural, is not technically feasible if cancer can potentially occur at any level of exposure (i.e., the linear non-threshold theory). Consequently, it is important to have an operational concept of safety which is more practical than that of zero risk. Such an approach uses the concept of acceptable or essentially negligible risk to determine the exposure levels at which carcinogens are regulated. Acceptable risk has been defined as one that is "so small, whose consequences are so slight, or whose associated benefits (perceived or real) are so great that persons or groups in society are willing to take or be subjected to that risk". The level of risk where remedial action is recommended will vary according to the "agent or process being regulated, the economic and social costs and benefits and technology factors". In accordance with the system used by the International Agency for Research on Cancer (IARC) to assess the strength of the evidence for human carcinogenicity, the ten exposures reviewed here can be grouped into three broad categories, with some exposures occupying more than one and the first category-human carcinogens-should be subdivided. Tables 1-4 refer to these categories. For many of the exposures discussed here, ongoing etiological research awaits methods development, particularly in exposure assessment.

Health outcomes of low-dose ionizing radiation exposure among medical workers: a cohort study of the Canadian national dose registry of radiation workers.

BACKGROUND: Medical workers can be exposed to low-dose ionizing radiation from various sources. The potential cancer risks associated with ionizing radiation exposure have been derived from cohort studies of Japanese atomic bomb survivors who had experienced acute, high-level exposure. Since such extrapolations are subject to uncertainty, direct information is needed on the risk associated with chronic low-dose occupational exposure to ionizing radiation. OBJECTIVES: To determine the occupational doses of ionizing radiation and examine possible associations with mortality rates and cancer incidence in a cohort of medical workers deriving from the National Dose Registry of Canada (NDR) over the period of 1951-1987. METHODS: Standardized mortality and incidence ratios (SMR and SIR, respectively) were ascertained by linking NDR data for a cohort of 67 562 medical workers (23 580 males and 43 982 females) with the data maintained by the Canadian Mortality, and Cancer Incidence databases. Dosimetry information was obtained from the National Dosimetry Services. RESULTS: During the follow-up period, 1309 incident cases of cancer (509 in males, 800 in females) and 1325 deaths (823 in males, 502 in females) were observed. Mortality from cancer and non-cancer causes was generally below expected as compared to the general Canadian population. Thyroid cancer incidence was significantly elevated both among males and females, with a combined SIR of 1.74 and 90% CI: 1.40-2.10. CONCLUSIONS: The findings confirm previous reports on an increased risk of the thyroid cancer among medical workers occupationally exposed to ionizing radiation. Over the last 50 years, radiation protection measures have been effective in reducing radiation exposures of medical workers to the current very low levels.

Decreases in occupational exposure to ionizing radiation among Canadian dental workers.

OBJECTIVE: To describe doses of ionizing radiation and their possible associations with mortality rates and cancer incidence among Canadian dental workers. METHODS: The National Dose Registry (NDR) of Canada was used to assess occupational dose of ionizing radiation received by dental workers. The NDR cohort includes 42,175 people classified as dental workers. Subjects in the NDR were linked to both the Canadian Mortality Database and the Canadian Cancer Database to ascertain cause of death and cancer incidence, respectively. RESULTS: The cohort consisted of 9,051 male and 33,124 female dental workers. A total of 656 incident cases of cancer and 558 deaths were observed. The standardized mortality ratio associated with all-cause mortality was 0.53 (90% confidence interval [CI] 0.49-0.57). The incidence of cancer among dental workers was lower than that for the Canadian population for all cancers except melanoma of the skin (for melanoma, the standardized incidence ratio was 1.46 [90% CI 1.14-1.85]). Occupational doses of ionizing radiation among dentists and dental workers have decreased markedly since the 1950s. CONCLUSIONS: Dental workers receive very low doses of ionizing radiation, and these doses do not appear to be associated with any increase in cancer incidence; the increased incidence of melanoma is more likely related to other risk factors such as exposure to ultraviolet radiation from sunlight.

Histology-related variation in the treatment and survival of patients with lung carcinoma in Canada.

OBJECTIVES: The aim of the study was to examine histologic differences in lung cancer treatment and survival, and to define recent survival trends in Ottawa, Canada. METHODS: From 1994 to 2000, 3,237 patients with invasive lung cancer were registered at the Ottawa Regional Cancer Centre (ORCC) and were followed up to 31 December 2001. Five-year relative survival rates (RSRs) and relative excess risks (RERs) of dying were calculated by stage and dominant initial treatment modalities for major cellular histologies using a relative survival model. RESULTS: The overall 5-year survival rate was 14%, and female patients had significantly better survival. Patients with stage I and II non-small cell lung cancer (NSCLC) who were treated by surgery alone were more likely to survive (5-year RSRs were 72 and 48%, respectively) than those who received other treatments. Patients with stage III NSCLC had a 5-year survival rate of 9% after chemotherapy plus radiotherapy, whereas stage IV patients who received only chemotherapy had better survival for up to 2 years than patients with other treatments. In cases of limited-stage small cell lung cancer (SCLC), survival was better for patients who received chemotherapy plus radiotherapy than for those who received only chemotherapy. CONCLUSIONS: The relatively superior survival of surgical patients with stage I NSCLC implies that a considerable number of patients have the potential to be treated successfully. The overall poor survival of lung cancer patients suggests a need for more national public health emphasis on lung cancer prevention, improved screening and early diagnosis, and better treatment.

An epidemiologic study of hepatocellular carcinoma in Canada.

BACKGROUND AND METHODS: To provide information on poorly described Canadian hepatocellular cancer epidemiology, we analyzed incident cases abstracted from the Canadian Cancer Registration Database (1969-1997) and Canadian annual death data (1969-1998). Age, sex, geographic distribution, and secular trends were described. Projection models were developed for the next decade. RESULTS: Results indicated much higher incidence and mortality rates in males than females, with substantial increases for both with age. Age-standardized incidence rates increased an average of 3.4% per year in males, 1.2% per year in females (1969-1997). Age-standardized mortality rates increased an average of 1.48% in males, but decreased an average of 0.46% per year in females (1969-1998). Join-point analysis of the linear trends in the age-standardized incidence and mortality rates suggested that a new trend started to emerge about 1991. The fitted non-linear multiplicative model predicted the occurrence of 1,565 new cases and 802 deaths in the year 2010. HCC incidence was the highest in British Colombia, followed by Quebec, and the lowest in the Atlantic region. CONCLUSIONS: Incidence rates of hepatocellular carcinoma have increased substantially, consistent with the reported increase in the prevalence of Hepatitis C Virus (HCV) and Hepatitis B Virus (HBV) infections in recent decades.

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.

Epidemiological study of Creutzfeldt-Jakob disease death certificates in Canada, 1979-2001.

INTRODUCTION: A descriptive epidemiological analysis to update trends of Creutzfeldt-Jakob disease (CJD) deaths, from 1979-2001, was undertaken. METHODS: Cases with CJD as underlying cause were extracted. Age-adjusted death rates by age, sex, and province were calculated. Information on birthplace, autopsy indications and type of work were examined for death certificates from 1979 to 1997. RESULTS: 462 cases were identified between 1979 and 1997. The average annual age-standardized mortality rate was 0.93 deaths per million persons during this period and 1.03 for 1998-2001. Persons 60 years or older demonstrated the highest average annual mortality rate. Rates were slightly higher among males and increased with age. Persons born in Canada accounted for 72% of deaths. Cause of death was verified by autopsy for 9.1% of patients while 21% of deaths indicated that additional information relating to underlying cause was expected. The service industry occupation represented the largest mortality (Quebec does not capture these data). CONCLUSIONS: Canadian rates are consistent with those of the United States and slightly higher than those of certain European countries. Approximately 44% of CJD cases had an autopsy record, though many were incomplete. We are unable to determine a relation with occupation. We recommend annual analysis of CJD death registrations for updated surveillance of trends, as mortality data are an efficient tool for monitoring incidence.

Increasing incidence of non-Hodgkin's lymphoma in Canada, 1970-1996: age-period-cohort analysis.

Previous studies have shown that the incidence of non-Hodgkin's lymphoma (NHL) has increased in many parts of the world in recent decades. Using data obtained from the Canadian Cancer Registry, the present study examined time trends in NHL incidence in Canada between 1970 and 1996 and the effects of age, period of diagnosis and birth cohort on incidence patterns for each sex separately. Results showed that overall age-adjusted incidence rates increased substantially, from 7.3 and 5.2 per 100,000 in 1970-1971 to 14.0 and 10.0 per 100,000 in 1995-1996 in males and females, respectively. Diffuse lymphoma was the major histological subtype, accounting for approximately 76% of NHL cases over the 27-year period. The data suggest that period effects have played a major role, although birth cohort effects may also have been involved. Sex-specific patterns of the incidence were similar over the time period of diagnosis but were distinct among recent birth cohorts. In conclusion, there is in fact a marked increase in NHL in Canada which cannot be explained in terms of improvements in diagnosis, changes in NHL classification and the increase in AIDS-associated NHL alone. The birth cohort effect in NHL suggests that changes in risk factors may have contributed to the observed increase.

Occupational exposure to chemical and petrochemical industries and bladder cancer risk in four western Canadian provinces.

Occupational factors have been proposed to play a critical role in bladder cancer. This population-based case-control study was conducted to confirm the association between selected occupational and non-occupational risk factors and risk of bladder cancer using data collected from the four western Canadian provinces. Unconditional logistic regression analyses were based on 549 histologically confirmed bladder cancer cases and 1099 controls. Bladder cancer risk was found to increase with increasing pack-years of cigarette smoking with an odds ratio (OR) in the highest quartile of 3.32 (95% confidence interval [CI], 2.28-4.82). A dose-response relationship was demonstrated between bladder cancer and pack-years of smoking (p < 0.0001). A positive trend was observed with coffee consumption in men (p < 0.0001), with the highest risk in the highest category of exposure: drinkers of four cups or more per day had an OR of 1.77 (95% CI 1.11-2.82). Increased bladder cancer risk was associated with self-reported exposure at work to several chemicals: asbestos (OR 1.69 [95% CI 1.07-2.65]); mineral, cutting or lubricating oil (1.64 [95% CI 1.06-2.55]); benzidine (2.20 [95% CI 1.00-4.87]). The population attributable fraction (PAF) estimates were 51% for cigarette smoking, 17% for heavy coffee consumption, 10% for mineral, cutting or lubricating oil exposure, 6% for asbestos exposure, and 1% for benzidine exposure. Although self-reported chemical exposures have important limitations, the findings are suggestive of increased risk for several associations previously reported between chemical agents or industries and risk of bladder cancer.

Trends in mortality and graft failure for renal transplant patients.

BACKGROUND: Several important advances in general medical management both before and after renal transplantation have occurred over the last 5-15 years, however, few studies have formally examined trends in the outcomes of renal transplantation. We, therefore, aimed to determine the degree to which these advances have resulted in improved outcomes such as survival of patient and graft. METHODS: We analyzed the rates of death and graft failure among the 11,482 Canadians with end-stage renal disease who received a kidney transplant in 1981-98. Patients were followed from the date of transplantation to the date of graft failure, the date of death or the end of the observation period, namely, Dec. 31, 1998, depending on which was the earliest. Rate ratios for mortality and graft failure--ratios of the rate for each calendar period to the rate for the arbitrarily chosen reference period, 1981-85--were estimated with a piece-wise exponential model that adjusted for age, sex, ethnicity, primary renal diagnosis, follow-up time and donor-organ source. RESULTS: The rates and adjusted rate ratios for death and graft failure decreased significantly and steadily over time. Relative to 1981-85, the adjusted mortality rate ratios were 0.70 (95% confidence interval [CI] 0.54-0.89), 0.65 (95% CI 0.52-0.82) and 0.53 (95% CI 0.41-0.67) for 1986-89, 1990-94 and 1995-98 respectively, and the adjusted graft failure rate ratios were 0.68 (95% CI 0.60-0.78), 0.62 (95% CI 0.54-0.70) and 0.51 (95% CI 0.44-0.58) respectively. The decrease was mostly among the cadaveric-organ recipients. Calendar period was as important a predictor of outcome as well-known prognostic factors such as age and primary renal diagnosis. INTERPRETATION: Decreases in mortality rates are probably related to refinements in patient management. Decreases in graft failure rates are probably the result of a combination of improved immunotherapy and better management of nonimmunologic conditions such as hypertension and hyperlipidemia.