The report found the five-year prevalence rate for all types of cancers combined rose 2.1 percent per year from 1997 to 2008. Liver and thyroid cancer had the highest increase in prevalence rates, which were more than double the increase for any other type of cancer.
The use of "prevalence" is used in the study to refer to all cancers diagnosed within a given period among people alive on a specific date, while "incidence," in contrast, refers to newly occurring cases.
Despite the "relatively large" increases in prevalence of liver and thyroid cancer, prostate cancer remains the most common cancer in Canada, followed by breast cancer. Prevalence rates for prostate cancer had also risen substantially, increasing 3.0 percent per year from 1997 to 2008. Increases in the prevalence of breast cancer were more moderate.
According to Statistics Canada, an aging population may be one of several factors leading to the increase in prevalence rates.
Why do you think these rates have risen so much for liver and thyroid cancers?