Abstract
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Background
Survival from adult onset leukemia has increased substantially in Canada since at least the early 1990s. However, an analysis of the extent of this improvement by type of leukemia is lacking.
Data and Methods
Data are from the Canadian Cancer Registry, with mortality follow-up through record linkage to the Canadian Vital Statistics Death Database. Increases in five-year relative survival ratios (RSRs) between 1992-to-1994 and 2006-to-2008 were calculated by age and sex for all leukemias combined and for each of the main types.
Results
Increases in five-year RSRs were significant for all leukemia types studied, ranging from 9.2 percentage units for acute myeloid leukemia (AML) to 24.9 percentage units for chronic myeloid leukemia (CML). For all leukemias combined, additional adjustment for case-mix reduced the increase in survival from 14.6 to 11.8 units; increases were significant among both sexes and each age group. Improvement in survival for chronic lymphocytic leukemia (CLL) was greater at older ages. For AML, improvements were greater among people younger than age 55; no significant change was detected among those diagnosed at ages 75 to 99. A significant survival advantage for women relative to men was apparent in the 2006-to-2008 period for all leukemias combined and for CLL and CML.
Interpretation
Despite recent significant gains in survival for each main type of leukemia, room remains for improvement.
Keywords
Acute lymphoblastic leukemia, acute myeloid leukemia, chronic lymphoblastic leukemia, chronic myeloid leukemia, neoplasms, population-based, registries, relative survival, survival analysis
Findings
In Canada, leukemia is diagnosed at a rate of 15 cases per 100,000 persons, and accounts for 3% of all new primary cancers (excluding non-melanoma skin). Most cases can be classified into one of four main types: acute lymphocytic (ALL), chronic lymphocytic (CLL), acute myeloid (AML), and chronic myeloid (CML). Despite etiologic and epidemiologic differences in these types, leukemia is often presented in the collective for convenience in reporting. [Full Text]
Authors
Larry F. Ellison (larry.ellison@canada.ca) is with the Health Statistics Division at Statistics Canada, Ottawa, Ontario.
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What is already known on this subject?
- Substantial improvements in survival among adults diagnosed with leukemia have been reported, primarily based on data from the United States and Sweden.
- The extent of improvements varied by the type of leukemia and the age at onset.
- A 15% increase in the five-year age-standardized relative survival ratio (RSR) has been noted among adults in Canada diagnosed with leukemia between 1992-to-1994 and 2006-to-2008.
- Canadian estimates of age-standardized five-year relative survival for all leukemias combined do not differ significantly by sex.
What does this study add?
- Between 1992-to-1994 and 2006-to-2008, survival improved significantly for the main types of leukemia.
- The largest gain―24.9 percentage units―was among those diagnosed with chronic myeloid leukemia; survival improved substantially in each age group.
- For acute myeloid leukemia, improvements in survival were greater among people diagnosed before age 55; no significant change was detected among those diagnosed at ages 75 to 99.
- Additional adjustment for case-mix reduced the magnitude of the increase in five-year relative survival for all leukemias combined, and revealed a significant survival advantage for women relative to men.
- An advantage for women was also noted among those diagnosed with chronic myeloid and chronic lymphocytic leukemia.
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