Abstract
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Background
Monitoring the progress of cancer survival in a population over time is an important part of cancer surveillance.
Data and methods
Data are from the Canadian Cancer Registry with mortality follow-up through record linkage to the Canadian Vital Statistics Death Database and tax files. Net survival (NS) was derived using the Pohar Perme method. Predicted estimates of NS for the period from 2012 to 2014 were calculated using the period method. Age-standardized and age-specific changes in five-year NS between the periods from 1992 to 1994 and 2012 to 2014 were determined for 30 individual cancers.
Results
Predicted five-year NS for 2012 to 2014 ranged from 98% for thyroid cancer to 7% for mesothelioma. Between 1992 to 1994 and 2012 to 2014, improvements in five-year age‐standardized NS were greatest for chronic myeloid leukemia (23.9 percentage points), though a large majority of the increase occurred in the first decade. Increases exceeding 15.0 percentage points were also observed for non-Hodgkin lymphoma (19.5), cancer of the small intestine (17.4) and multiple myeloma (16.9). In contrast, little to no improvement was observed for cancers of the anus, larynx, soft tissue or uterus, or for mesothelioma. Increases in five-year NS were greatest for chronic myeloid leukemia in each age group with the exception of those aged 75 to 84 years (thyroid).
Interpretation
This study reveals important areas of progress in cancer outcomes in Canada since the early 1990s. It also sheds light on cancers for which there has seemingly been no improvement in five-year net survival over a 20-year period.
Keywords
neoplasms, net survival, population-based, registries, prognosis, survival analysis
Findings
Deriving cancer survival estimates on a population basis permits the monitoring of progress in outcomes over time. Net survival (NS) is the preferred method for comparing cancer survival in population-based cancer studies because it adjusts for the fact that different populations may have different levels of background risk of death. This measure of cancer survival may be thought of as the survival probability that would be observed in the hypothetical situation where the cancer of interest is the only possible cause of death. [Full Text]
Author
Larry F. Ellison (larry.ellison@canada.ca) is with the Health Statistics Division at Statistics Canada in Ottawa.
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