Trends in diabetes treatment in Canadians, 1994-2004.

OBJECTIVE: To examine trends in the treatment of diabetes using the biannual interviews of the longitudinal National Population Health Survey (NPHS), 1994-2004 as they relate to changes in Clinical Practice Guidelines (CPGs). METHODS: A sample of 17 276 Canadians 18 years and older was selected for repeated interviews at two-year intervals from 1994 to 2004 for the NPHS. The population used for this study includes all respondents aged 40 to 79 for any of the cycles. RESULTS: CPGs issued by the Canadian Diabetes Association in 1998 and 2004 recommend a stepwise introduction of lifestyle changes, to be followed by single then multiple oral antidiabetic agents (OA), and finally insulin until adequate control is achieved. While the use of OA increased, only a small proportion indicated diet or physical exercise as part of their treatment; those with no drug treatment reported less diet modification and physical exercise. Antihypertensives and statin use in Canadians with diabetes increased to double that of Canadians overall, but remained underutilized. CONCLUSION: This study provides an update on the treatment of diabetes in Canada between 1994 and 2004. While some changes in diabetes treatment were compatible with CPGs, there is room for improvement, especially in lifestyle modifications.

Herbicides and cancer.

Herbicides are a heterogeneous class of chemicals used in agriculture, forestry, and urban settings to kill weeds, shrubs, and broad-leaved trees. The role of herbicides in the etiology of cancer is controversial. Potential studies for review were identified through a MEDLINE search and from a check of references in related review articles. This review of the literature shows reasonable evidence suggesting that occupational exposure to phenoxy herbicides results in increased risk of developing non-Hodgkin's lymphoma. Several studies have noted large increases in risk of soft-tissue sarcomas with phenoxy herbicide exposure. In contrast, others have failed to observe increased risks, and evidence of an exposure-risk relationship is lacking. Although there have been too few appropriate studies for adequate assessment of risk of cancer at other sites, some findings have linked herbicide exposure with cancers of the colon, lung, nose, prostate, and ovary as well as to leukemia and multiple myeloma. Future studies must better identify and quantify the nature of herbicide exposures. In the interim, it seems only prudent to monitor and promote safety practices among persons occupationally exposed to phenoxy herbicides, particularly farmers and professional sprayers.

Mortality study of Canadian male farm operators: non-Hodgkin's lymphoma mortality and agricultural practices in Saskatchewan.

A cohort study of the mortality experience (1971-1985) of male Saskatchewan farmers has been conducted. This study involved linkage of records of the almost 70,000 male farmers identified on the 1971 Census of Agriculture and the corresponding Census of Population to mortality records. Pesticide exposure indices for individual farm operators for the year 1970 were derived from the 1971 Census of Agriculture records. Although the cohort as a whole had no excess mortality for any specific causes of death, including non-Hodgkin's lymphoma, significant dose-response relationships were noted between risk of non-Hodgkin's lymphoma and acres sprayed in 1970 with herbicides, as well as with dollars spent on fuel and oil for farm purposes in 1970. Using Poisson regression modeling, we found that relative risks for the highest level of herbicide use (greater than or equal to 250 acres sprayed) and fuel purchased in 1970 (greater than or equal to $900) on farms less than 1,000 acres total area were 2.2 (95% confidence interval = 1.0-4.6) and 2.3 (95% confidence interval = 1.1-4.7), respectively.

Radon and cancers other than lung cancer in underground miners: a collaborative analysis of 11 studies.

BACKGROUND: Exposure to the radioactive gas radon and its progeny (222Rn and its radioactive decay products) has recently been linked to a variety of cancers other than lung cancer in geographic correlation studies of domestic radon exposure and in individual cohorts of occupationally exposed miners. PURPOSE: This study was designed to characterize further the risks for cancers other than lung cancer (i.e., non-lung cancers) from atmospheric radon. METHODS: Mortality from non-lung cancer was examined in a collaborative analysis of data from 11 cohorts of underground miners in which radon-related excesses of lung cancer had been established. The study included 64,209 men who were employed in the mines for 6.4 years on average, received average cumulative exposures of 155 working-level months (WLM), and were followed for 16.9 years on average. RESULTS: For all non-lung cancers combined, mortality was close to that expected from mortality rates in the areas surrounding the mines (ratio of observed to expected deaths [O/E] = 1.01; 95% confidence interval [CI] = 0.95-1.07, based on 1179 deaths), and mortality did not increase with increasing cumulative exposure. Among 28 individual cancer categories, statistically significant increases in mortality for cancers of the stomach (O/E = 1.33; 95% CI = 1.16-1.52) and liver (O/E = 1.73; 95% CI = 1.29-2.28) and statistically significant decreases for cancers of the tongue and mouth (O/E = 0.52; 95% CI = 0.26-0.93), pharynx (O/E = 0.35; 95% CI = 0.16-0.66), and colon (O/E = 0.77; 95% CI = 0.63-0.95) were observed. For leukemia, mortality was increased in the period less than 10 years since starting work (O/E = 1.93; 95% CI = 1.19-2.95) but not subsequently. For none of these diseases was mortality significantly related to cumulative exposure. Among the remaining individual categories of non-lung cancer, mortality was related to cumulative exposure only for cancer of the pancreas (excess relative risk per WLM = 0.07%; 95% CI = 0.01-0.12) and, in the period less than 10 years since the start of employment, for other and unspecified cancers (excess relative risk per WLM = 0.22%; 95% CI = 0.08-0.37). CONCLUSIONS: The increases in mortality from stomach and liver cancers and leukemia are unlikely to have been caused by radon, since they are unrelated to cumulative exposure. The association between cumulative exposure and pancreatic cancer seems likely to be a chance finding, while the association between cumulative exposure and other and unspecified cancers was caused by deaths certified as due to carcinomatosis (widespread disseminated cancer throughout the body) that were likely to have been due to lung cancers. This study, therefore, provides considerable evidence that high concentrations of radon in air do not cause a material risk of mortality from cancers other than lung cancer. IMPLICATIONS: Protection standards for radon should continue to be based on consideration of the lung cancer risk alone.

Lung cancer in radon-exposed miners and estimation of risk from indoor exposure.

BACKGROUND: Radioactive radon is an inert gas that can migrate from soils and rocks and accumulate in enclosed areas, such as homes and underground mines. Studies of miners show that exposure to radon decay products causes lung cancer. Consequently, it is of public health interest to estimate accurately the consequences of daily, low-level exposure in homes to this known carcinogen. Epidemiologic studies of residential radon exposure are burdened by an inability to estimate exposure accurately, low total exposure, and subsequent small excess risks. As a result, the studies have been inconclusive to date. Estimates of the hazard posed by residential radon have been based on analyses of data on miners, with recent estimates based on a pooling of four occupational cohort studies of miners, including 360 lung cancer deaths. PURPOSE: To more fully describe the lung cancer risk in radon-exposed miners, we pooled original data from 11 studies of radon-exposed underground miners, conducted a comprehensive analysis, and developed models for estimating radon-associated lung cancer risk. METHODS: We pooled original data from 11 cohort studies of radon-exposed underground miners, including 65,000 men and more than 2700 lung cancer deaths, and fit various relative risk (RR) regression models. RESULTS: The RR relationship for cumulative radon progeny exposure was consistently linear in the range of miner exposures, suggesting that exposures at lower levels, such as in homes, would carry some risk. The exposure-response trend for never-smokers was threefold the trend for smokers, indicating a greater RR for exposure in never-smokers. The RR from exposure diminished with time since the exposure occurred. For equal total exposure, exposures of long duration (and low rate) were more harmful than exposures of short duration (and high rate). CONCLUSIONS: In the miners, about 40% of all lung cancer deaths may be due to radon progeny exposure, 70% of lung cancer deaths in never-smokers, and 39% of lung cancer deaths in smokers. In the United States, 10% of all lung cancer deaths might be due to indoor radon exposure, 11% of lung cancer deaths in smokers, and 30% of lung cancer deaths in never-smokers. This risk model estimates that reducing radon in all homes exceeding the U. S. Environmental Protection Agency's recommended action level may reduce lung cancer deaths about 2%-4%. These estimates should be interpreted with caution, because concomitant exposures of miners to agents such as arsenic or diesel exhaust may modify the radon effect and, when considered together with other differences between homes and mines, might reduce the generalizability of findings in miners.

Use of paediatric versus adult oncology treatment centres by adolescents 15-19 years old: the Canadian Childhood Cancer Surveillance and Control Program.

The aim of this study was to evaluate the treatment patterns of adolescents with cancer in Canada to ensure this population is receiving the most appropriate care. The Treatment and Outcome Surveillance (TOS) system was compared with the Canadian Cancer Registry (CCR) to estimate the proportion of adolescents (15-19 years) treated in Canadian paediatric oncology centres from 1995 to 2000 inclusive. Using TOS, the demographic, disease, and clinical characteristics of adolescents treated in paediatric versus adult centres in the Prairies were compared and differences were tested statistically. Approximately 30% of Canadian adolescents with cancer were treated in a paediatric centre. Adolescents treated in an adult centre were older at diagnosis and more likely to have carcinoma or germ cell tumours. The time between symptom onset and first treatment was longer for these adolescents, primarily due to the time between first health-care contact and assessment by a treating oncologist or surgeon. They were less likely to be enrolled in a clinical trial. These results suggest that care for adolescents with cancer in Canada is less satisfactory than for younger children, and can be improved.

Sex inequality in kidney transplantation rates.

BACKGROUND: Men in the United States undergoing renal replacement therapy are more likely than women to receive a kidney transplant. However, the ability to pay may, in part, be responsible for this finding. OBJECTIVE: To compare adult male and female transplantation rates in a setting in which equal access to medical treatment is assumed. METHODS: Using data from the Canadian Organ Replacement Register, the rate of first transplantations was computed for the 20, 131 men and the 13,458 women aged 20 years or older who initiated renal replacement therapy between January 1, 1981, and December 31, 1996. Poisson regression analysis was used to estimate the male-female transplantation rate ratio, adjusting for age, race, province, calendar period, underlying disease leading to renal failure, and dialytic modality. Actuarial survival methods were used to compare transplantation probability for covariable-matched cohorts of men and women. RESULTS: Men experienced 20% greater covariable-adjusted kidney transplantation rates relative to women (rate ratio, 1.20; 95% confidence interval, 1.13-1.27). The sex disparity was stronger for cadaveric transplants (rate ratio, 1.23) compared with those from living donors (rate ratio, 1.10). The 5-year probability of receiving a transplant was 47% for men and 39% for women within covariable-matched cohorts (P<.001). The sex disparity in transplantation rates increased with increasing age. The sex effect was weaker among whites and Oriental persons (Chinese, Japanese, Vietnamese, Cambodian, Laotian, Filipino, Malaysian, Indonesian, and Korean) and stronger among blacks, Asian Indians (Indian, Pakistani, and Sri Lankan), and North American Indians (aboriginal). CONCLUSION: Since survival probability and quality of life are superior for patients who undergo transplantation relative to those who undergo dialysis, an increased effort should be made to distribute kidneys available for transplantation more equitably by sex among patients undergoing renal replacement therapy.

Major risk factors for cardiovascular disease mortality in adults: results from the Nutrition Canada Survey cohort.

The cardiovascular mortality experience of over 7000 Canadians ages 35-79 years free of self-reported heart disease or stroke who participated in the Nutrition Canada survey is presented. The effects of various risk factors on cardiovascular disease mortality were assessed using multivariate Poisson regression analyses. Factors associated with a significantly increased risk of dying included cigarette smoking, hypertension, diabetes and, for women, serum cholesterol. Relative risks were similar for those ages 35-64 years compared to those 65-79 years for diabetes but were higher among those 35-64 years for cigarette smoking, diastolic hypertension, obesity and serum cholesterol (females only). Individuals drinking three or more drinks daily had a relative risk of 3.18 for stroke. Population attributable risks for smoking, hypertension, elevated serum cholesterol and diabetes, respectively, were 47%, 21%, 7% and 8% for men and 10%, 21% 18% and 16% for women.

End-stage renal disease projections for Canada to 2005 using Poisson and Markov models.

BACKGROUND: End-stage renal disease (ESRD) incidence and prevalence are increasing in many countries worldwide. Due to the high cost of therapy, predicting future numbers of patients requiring dialysis and transplantation is necessary for health care planners. Projecting therapy-specific chronic disease prevalence is inherently problematic, and examples of suitable models and their application are sparse. When applied, rarely was the adequacy of such models evaluated. METHODS: We describe and illustrate a method for projecting therapy-specific ESRD prevalence in Canada for 1995-2005 using data obtained from the Canadian Organ Replacement Register. The projections combine the Poisson model for incidence rates and a Markov model for patient follow-up. Model adequacy is empirically validated by data-splitting. RESULTS: Large increases in ESRD prevalence are expected in Canada, with an average annual increase of 6.9% projected for 1995-2005. Upon validation, the projection model based on 1981-1987 data was able to predict 1994 prevalence within 1%, while projected therapy-specific prevalences closely approximated those observed. CONCLUSIONS: Therapy-specific ESRD prevalence was successfully projected using Poisson and Markov models. Where multistate prevalence forecasts are required, the method could be augmented for application to various other chronic diseases.

Risk factors for postneonatal mortality: results from a record linkage study.

A population-based computer record linkage of infant births and deaths was conducted for 1978 and 1979 covering Canadian provinces. Birthweight was inversely related to risk of postneonatal death for all causes examined, including accidental deaths. Length of gestation was inversely associated with risk, but the strength of the relationship was much weaker than that noted for birthweight. A logistic regression model was used to assess the effects of variables, as reported on birth certificates, on postneonatal mortality. Maternal age less than 25 years, unmarried marital status and one or more previous births were all statistically significantly related to increased risk.

Radon-progeny exposure and lung cancer risk in a cohort of Newfoundland fluorspar miners.

Although radon is a well-established lung carcinogen, there are uncertainties concerning the exposure-response relationship, whether exposures in early life are particularly hazardous, and how smoking affects the risks associated with radon exposure. A cohort study of the mortality experience of 1,743 underground fluorspar miners and 321 surface workers from 1950 to 1984 reported previously has been extended to include 6 additional years of follow-up (1985-1990). A statistically significant relationship was noted between radon-progeny exposure and risk of lung cancer mortality. Our analysis found no effect for age at first exposure. Attained age was strongly predictive of excess relative risk (ERR) per working level month (WLM) of radon exposure, falling from 0.025 for those aged less than 50 years to 0.002 for those 70 years or older. An inverse exposure-rate effect was also observed, wherein for equal total exposure, a high exposure rate (and short duration) is less harmful than a low exposure rate (and long duration). The ERR/WLM increased from 0.0019 for exposures of less than 10 years to 0.0076 for exposures of 20 or more years. The analysis of time-since-exposure windows revealed a greater ERR/WLM for exposures received in more recent periods, similar to the result for time since last exposure. Excess relative risks per WLM were higher for current smokers than for nonsmokers (never and former smokers). Analyses were consistent with a multiplicative relationship between radon-progeny exposure and current smoking and the risk of lung cancer. The assessment of radon exposure and lung cancer risk should incorporate the effects of exposure rate, time since exposure, smoking status and attained age.

Estimating lung cancer mortality from residential radon using data for low exposures of miners.

Some recent estimates of lung cancer risk from exposure to radon progeny in homes have been based on models developed from a pooled analysis of 11 cohorts of underground miners exposed to radon. While some miners were exposed to over 10,000 working level months (WLM), mean exposure among exposed miners was 162 WLM, about 10 times the exposure from lifetime residence in an average house and about three times the exposure from lifetime residence at the "action level" suggested by the U.S. Environmental Protection Agency. The extrapolation of lung cancer risk from the higher exposures in the miners to the generally lower exposures in the home is a substantial source of uncertainty in the assessment of the risk of indoor radon. Using the pooled data for the miners, analyses of lung cancer risk were carried out on data restricted to lower exposures, either <50 WLM or <100 WLM. In the pooled data, there were 115 lung cancer cases among workers with no occupational WLM exposure and 2,674 among exposed miners, with 353 and 562 lung cancer cases in miners with <50 WLM and <100 WLM, respectively. Relative risks (RRs) for categories of WLM based on deciles exhibited a statistically significant increasing trend with exposure in each of the restricted data sets. In the restricted data, there was little evidence of departures from a linear excess relative risk model in cumulative exposure, although power to assess alternative exposure-response trends was limited. The general patterns of declining excess RR per WLM with attained age, time since exposure and exposure rate seen in the unrestricted data were similar to the patterns found in the restricted data. Risk models based on the unrestricted data for miners provided an excellent fit to the restricted data, suggesting substantial internal validity in the projection of risk from miners with high exposures to those with low exposures. Estimates of attributable risk for lung cancer (10-14%) in the U.S. from residential radon based on models from the unrestricted data were similar to estimates based on the data for miners receiving low exposures.

Cigarette smoking and sperm density: a meta-analysis.

OBJECTIVE: To quantify, through meta-analysis techniques, the association between cigarette smoking and sperm density. METHODS: The logarithm of the ratio of mean sperm density for smokers to that for nonsmokers for the studies included in this meta-analysis was regressed against a constant, an indicator of study population source (infertility clinic patients or normal men), minimum number of cigarettes smoked per day among smokers (< 10, > or = 10), exclusion of azoospermic men (yes/no), number of semen specimens analyzed (one versus two), and blinding of laboratory personnel to the smoking status of the study participants (yes/no). Regression analyses were performed both unweighted and weighted inversely by study size. A qualitative and quantitative assessment of the relationship between the numbers of cigarettes smoked per day and sperm density was performed. RESULTS: Results of the meta-analysis indicate that smokers' sperm density is on average 13% to 17% (95% confidence interval = 8.0, 21.5) lower than that of nonsmokers. No other factors besides cigarette smoking were found to be independent predictors of sperm density. No clear dose-response relationships between the numbers of cigarettes smoked per day and sperm density emerged. Research conducted by the authors supports the findings of the meta-analysis. CONCLUSION: Cigarette smoking is associated with lowered sperm density. The inconsistency in the literature with regard to this conclusion appears to be the result of small sample sizes in most studies.

Coronary heart disease mortality among Newfoundland fluorspar miners.

OBJECTIVES: The association between cumulative radon exposure and coronary heart disease mortality was studied in a retrospective cohort investigation of Newfoundland fluorspar miners. METHODS: Multivariate Poisson regression techniques were used to estimate relative risks of coronary heart disease mortality by level of radon exposure. Relative risks (RR) were adjusted by attained age, calendar period, duration of exposure, and smoking status. Death from coronary heart disease was the outcome measure of interest and was identified by record linkage to the Canadian Mortality Database. RESULTS: An elevated risk of mortality from coronary heart disease was observed among miners with a cumulative radon exposure exceeding 1000 working-level months [RR 1.5, 95% confidence interval (95% CI) 0.77-2.75]. The association between radon exposure and coronary heart disease was not statistically significant according to a test for trend across exposure categories (P = 0.09). The smokers were 1.8 times more likely than the nonsmokers to die from coronary heart disease (95% CI 1.1-2.8). CONCLUSIONS: These results suggest a positive association between coronary heart disease and radon exposure. However, these findings should be interpreted cautiously due to the inability to control for the confounding influence of other known risk factors of coronary heart disease.

Non-Hodgkin's lymphoma and agricultural practices in the prairie provinces of Canada.

OBJECTIVES: The aim of this study was to provide an update of a cohort study (1971-1985) that previously reported a significant trend in the risk of non-Hodgkin's lymphoma among male Saskatchewan farm operators according to fuel-oil expenditures and herbicide spraying for farms less than 1000 acres (2570 hectares) by including two additional Canadian prairie provinces, two additional years of follow-up, and data from the 1981 Census of Agriculture. METHODS: Information on farmers from 1971 records of the Census of Agriculture was linked to 1971 records of the Census of Population, to 1981 records of the Census of Agriculture, and to death records. Poisson regression was used to estimate risks according to herbicide spraying and fuel and oil expenditures. RESULTS: The addition of a further two years of follow-up resulted in lower risk estimates associated with herbicide spraying for Saskatchewan. No excess risk was observed between herbicide spraying and non-Hodgkin's lymphoma for Alberta or Manitoba in the 1971 data. However, a significantly increased risk of non-Hodgkin's lymphoma according to acres sprayed with herbicides was observed for the three provinces combined when the herbicide spraying data from the 1981 Census of Agriculture was used [> or = 380 acres (> or = 939 hectares) sprayed, rate ratio 2.11, 95% confidence interval 1.1-3.9]. CONCLUSIONS: Although the current results are not entirely consistent with the original Saskatchewan analysis, they support the overall finding of an association between herbicides and risk of fatal non-Hodgkins lymphoma. Prospective cohort studies are needed to overcome the limitations of existing epidemiologic studies.

Comparing mortality rates on CAPD/CCPD and hemodialysis. The Canadian experience: fact or fiction?

OBJECTIVE: To compare mortality rates on hemodialysis (HD) to rates on continuous ambulatory/cyclic peritoneal dialysis (CAPD/CCPD), to contrast our results with those of other recent investigations, and to discuss reasons for discrepancies. DATA SOURCES: Patient-specific data obtained from the Canadian Organ Replacement Register on patients initiating renal replacement therapy (RRT) between 1 January 1990 and 31 December 1995 (n = 14 483). Recent mortality comparisons of CAPD and HD. MAIN OUTCOME MEASURES: Mortality rate ratio (RR) based on "as-treated" (AT) analysis incorporating treatment modality switches and adjusting for age, primary renal diagnosis, and comorbid conditions using Poisson regression. Hazard ratios (HR) were estimated using Cox regression and based on an "intent-to-treat" (ITT) analysis wherein patients were classified based on dialytic modality received on follow-up day 90. RESULTS: Adjusted mortality rates were significantly decreased on CAPD/CCPD relative to HD [RR = 0.73, 95% confidence interval (CI) = (0.69, 0.77)] based on the AT analysis. Most of the protective effect of CAPD/CCPD was concentrated in the first 2 years of follow-up post-RRT initiation. Based on the ITT analysis, the estimated CAPD/ CCPD effect was greatly reduced, with HR = 0.93 (0.87, 0.99). CONCLUSIONS: We provide further evidence that CAPD/CCPD is not an inferior dialytic modality to HD, particularly in the short term. Comparing mortality rates on CAPD/CCPD and HD is inherently difficult due to the potential for bias. Discrepancies between our results and those of previous investigations, and variability in findings among previous studies, relate to differences in clinical and demographic setting, patient populations, study design, statistical methods, and interaction between the dialytic modality effect and various other covariables.

Indian Reserve and registered Indian mortality in Canada.

Although in demand, there is only limited information available regarding the patterns of mortality among Natives in Canada. Mortality rates for residents of Canadian Indian Reserves (IRs) and Registered Indians were calculated for the periods 1979-1988 and 1981 respectively. Proportionate mortality ratios and age-standardized mortality rates for residents of Indian Reserves were similar to those obtained for Registered Indians. Standardized mortality ratios were calculated using both Canadian mortality and mortality in selected isolated rural populations as references. Dramatically increased risks were observed among Native populations for mortality from alcoholism/liver cirrhosis, homicide, suicide and pneumonia. While SMRs calculated using mortality rates in rural populations appeared to be preferable to those using Canadian rates, the use of Canadian rates does not alter the conclusion that IRs have significantly elevated mortality from environmental and social causes which, although improving, require continuing control efforts.

Leukemia mortality and farming in the prairie provinces of Canada.

BACKGROUND: An increased risk of leukemia has been previously noted among farmers. PURPOSE: To examine the risk of fatal leukemia according to various farming practices in a large cohort of Canadian farm operators. METHODS: A cohort study of the mortality experience (1971-1987) 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. RESULTS: We observed a statistically significant test for trend (p = 0.03) between leukemia mortality and the number of chickens and/or turkeys owned (relative risk for > or = 130 chickens and/or turkeys = 1.32, 95% CI = 0.99, 1.77). No association was observed between leukemia mortality and either insecticide or herbicide use. CONCLUSIONS: Further research is necessary regarding why farmers exposed to chickens may be at an increased risk of leukemia.

Long-term survival rates among patients with cancer in Saskatchewan, 1967-1986.

We calculated relative survival rates from 5 to 15 years after diagnosis for cancer cases diagnosed in Saskatchewan, Canada, between 1967 and 1986. Cancers with high 15-year relative survival (greater than 60%) included lip, melanoma among women, other male genital sites, and corpus uteri. As anticipated, relative survival rates declined with increasing length of follow-up, with the largest relative declines noted among those in the oldest age group (65+ years). Only small declines in relative survival were noted for cancers of the colon and cervix with increasing length of follow-up. Improved survival of cases diagnosed in the period 1980-1984 compared to 1970-1974 was observed for all sites combined, as well as the following sites: colon, lung, prostate, brain, ill-defined sites, non-Hodgkin's lymphoma, and lymphoid leukemia. For colorectal cancer, stage at diagnosis was a more important independent predictor of survival than age.

The impending Canadian prostate cancer epidemic.

PURPOSE: To model and forecast prostate cancer incidence and mortality in Canada to the year 2016. METHODS: Bivariate multiplicative models of prostate cancer incidence and mortality for Canadian men aged 45 years or older, linear in time and Weibull in age, were fitted using weighted non-linear regression. RESULTS: The number of incident cases of prostate cancer is forecast to increase from 11,355, observed in 1990, to 26,900 by the year 2010 and to 35,200 by the year 2016. The number of deaths are estimated to climb from 3,424, observed in 1991, to an estimated 6,300 by the year 2010, and to 7,800 by the year 2016. CONCLUSIONS: The dramatic increase in prostate cancer rates with age, coupled with the expected large increase in the elderly Canadian male population and steadily increasing prostate cancer incidence rates will produce very large increases in the number of men who will have prostate cancer over the next 20 years. This has important implications for health care delivery in the future.