R. Semenciw

Trends in childhood injury mortality in Canada, 1979–2002

Objective: To examine national trends in mortality rates for injuries among Canadian children younger than 15 years in 1979–2002. Methods: Data on injury deaths were obtained from the Canadian Vital Statistics system at Statistics Canada. Injuries were classified using the codes for external cause of injury and poisoning (E-codes) by intent and by mechanism. Mortality rates were age adjusted to the 1990 world standard population. Negative binomial regression was used to estimate the secular trends. Results: Annual mortality rates for total and unintentional injuries declined substantially (from 23.8 and 21.7 in 1979 to 7.2 and 5.8 in 2002, respectively), whereas suicide deaths among children aged 10–14 showed an increasing trend. All Canadian provinces and territories showed a decreasing trend in mortality rates of total injuries. Motor vehicle related injuries were the most common cause of injury deaths (accounted for an average of 36.4% of total injury deaths), followed by suffocation (14.3%), drowning (13.5%), and burning (11.1%); however, suffocation was the leading cause for infants. The number of potential years of life lost due to injury before age 75 decreased from 89 343 in 1979 to 27 948 in 2002 for children aged 0–14 years. Conclusions: During the period 1979–2002, there were dramatic decreases in childhood mortality for total injuries and unintentional injuries as well as various degrees of reduction for all causes of injury except suffocation in children aged 10–14 years and drowning in infants. The reason for the reduction in injury mortality might be multifactoral.

Incidence of Second Primary Breast Cancer Among Women with a First Primary in Manitoba, Canada

Second primary breast cancer is of importance because of the increasing incidence of first primary breast cancer and improved survival. There is lack of information on the disease in Canada. We studied 14,220 women with a first primary breast cancer (invasive only) diagnosed during the period from 1970 to 1997, in Manitoba, Canada. A breast cancer was considered to be a second primary if it was an invasive lesion diagnosed at least six months after the diagnosis of an initial primary breast cancer. The incidence rate of second primary breast cancer was approximately six per 1,000 person-years, and the cumulative incidence during the 28-year study period was 14.3%. Average age at diagnosis of first primary breast cancer had increased significantly since 1970. The incidence was higher in 1975–1979, and there was no significant difference among other study periods after adjustment for the age at diagnosis of first primary breast cancer. Standardized incidence ratios showed no significant difference among six age groups after adjusting for calendar year. However, women with a first primary breast cancer had an increased risk of developing a second primary breast cancer compared with the risk of developing a first primary breast cancer among the general female population. The SIR was markedly greater among women who had a first primary breast cancer before the age of 40 years, and decreased significantly with increasing age at diagnosis of first primary breast cancer. The data provide epidemiological information on second primary breast cancer risk for the general female population in Manitoba, Canada.

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.

Methodological issues in the development of the Canadian Cancer Incidence Atlas.

The Canadian Cancer Incidence Atlas is among recent national atlases using incidence rather than mortality data. Methods used to assess the significance and spatial correlation of the age-standardized rates (ASIRs) for the 290 census divisions are described. The expected number of cases by area was used to determine cancer sites with sufficient cases to be mapped. ASIR significance was assessed using a simulation based on a Poisson distribution. The consistency of the observed case distributions with the Poisson distribution was examined. The bootstrap confidence interval (CI) for the ASIR developed by Swift was used in the atlas. Spatial correlation was assessed with Morans I/I(max) and the significance determined by a simulation in order to allow for area population variation. Data quality indicators typically used for cancer registries were presented, supplemented by a registry questionnaire.

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.

Survival Patterns for the Top Four Cancers in Canada: The Effects of Age, Region and Period

This study examined the variations in survival rates (1989–1991) and the trends (1969–1991), by sex, age and province, for patients diagnosed with breast, colorectal, lung or prostate cancer in Canada and compared the Canadian rates with those of nine American SEER registries. Five-year age-standardized relative survival rates (ASRs) were calculated, and the trends were estimated from variance-weighted linear regression of the ASRs for five periods of diagnosis (1969–1973, 1974–1978, 1979–1983, 1984–1988 and 1989–1991). In 1989–1991, the ASR varied among provinces for each cancer except female colorectal cancer. The lowest survival rates were observed in the youngest patients (15–44) for breast and prostate cancers, and in the oldest patients (75–99) of both sexes for lung and colorectal cancers. Over the five periods, a major trend toward improved survival was observed for breast, prostate and colorectal cancers (P<0.008), whereas no changes were seen for lung cancer. The ASRs in the western region were higher than in the Atlantic region over time (P<0.02) for each cancer. From the third period onward, the ASRs for Canadian patients with lung cancer were similar to those for the US patients and lower than for Canadian patients with breast, prostate or colorectal cancer. The observed increases in ASR for breast and prostate cancer are likely due to the increased use of screenings and the improved treatment modalities.