Summary of key findings

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Canadian trends in cancer prevalence

Five-year cancer prevalence rates for most cancers increased from January 1, 1997 to January 1, 2008.  Increases were relatively large for liver and thyroid cancer, while rates declined for cancers of the larynx and cervix.  The biggest disparity between the sexes was for cancer of the lung, where rates declined slightly among men, but continued to increase among women.

For all cancers combined, the five-year prevalence rate at the beginning of 2008 was 1,490 cases per 100,000 persons. The most prevalent cancer was prostate cancer (610 cases per 100,000).  In comparison, the corresponding prevalence rates for thyroid (53.1), cervical (32.5), laryngeal (10.0) and liver cancer (6.2), were considerably lower.

In general, cancer care services required within the first five years after diagnosis include primary treatment and supportive care, followed by close clinical assessment for recurrence.

Several factors may lead to increases in prevalence rates—including the aging of the population, improved detection of disease through advancements in screening, more extensive use of screening, increases in underlying risk factors for disease and improved survival of people with cancer.

For all cancers combined, roughly half of the reported average annual rates of increase for five-year prevalence were attributable to agiNg E. However, for individual cancers, the role of aging varied considerably.  For example, only about 20% of the increase in prevalence for liver cancer was due to agiNg E.

The five-year prevalence rate for all cancers combined rose by 2.1% per year from 1997 to 2008.

The average annual increases in five-year prevalence rates for liver and thyroid were more than double the increase for any other cancer.

The five-year liver cancer prevalence rate increased by 8.3% per year.  For thyroid cancer, the average annual increase was 7.9%; 3.7% from 1997 to the beginning of 2000, and 9.5% from 2000 to 2008.  Increases were higher in men for liver cancer, but higher in women for thyroid cancer.

Among the cancers considered in this study, declines in prevalence rates occurred only for cancers of the larynx and cervix.  For example, the annual average rates of decrease in five-year prevalence for laryngeal and cervical cancer were 1.9% and 1.5%, respectively. 

Prevalence rates for prostate cancer, the most common cancer in Canada, rose substantially—primarily due to the aging of the population over the study period.  For example, the five-year prevalence rate for this cancer increased by 3.0% per year from 1997 to 2008.

Substantial increases in prostate cancer prevalence rates occurred among men in all age groups younger than 70 years.  Average annual rate increases were highest at ages 40 to 49.  The size of the increase fell in each successively older age group.

Increases in the prevalence of breast cancer, the second most common cancer and the most common in women, were more moderate. The annual rate of increase in five-year breast cancer prevalence was about three times higher before the beginning of 2001 (2.3%) than afterward (0.7%).  Over the entire period, the five-year prevalence rate rose by an average of 1.3% per year.

Colorectal and lung cancer were the third and fourth most common cancers respectively.  The average increase in five-year colorectal cancer prevalence from 1997 to 2008 was 2.3% per year; 2.5% per year up to the beginning of 2003 and 1.9% per year afterward.  Increases for colorectal cancer were highest in the 20-to-39 year age group. 

For lung cancer, the five-year prevalence rate increased 2.6% per year since the beginning of 2005, up from a rate of less than 1% a year before this period.  Over the whole period, the rate increased by an average of 1.3% per year.

Between the sexes, changes in the prevalence rate of lung cancer diverged.  In men, the rate declined slightly, by 0.3% per year, but in women it increased by 3.0% per year.  This discrepancy was due to sharper decreases in smoking prevalence among men since the mid-1960s.

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For information about this article, contact Larry Ellison (613-951-5244; larry.ellison@statcan.gc.ca), Health Statistics Division, or Kathryn Wilkins (613-951-1769; kathryn.wilkins@statcan.gc.ca), Health Analysis Division.