Cancer in Ontario
As the incidence rate of cancer increases and death rate from cancer decreases, the number of people living with cancer in Ontario is expected to rise. Statistics show that the 5-year relative survival ratio for most common cancers has improved over time. Exceptions to this trend are bladder and uterine cancer.
See CSQI’s “Bladder cancer in Ontario” feature.
How do incidence, mortality, survival and prevalence relate to one another?
- Incidence is a measure of cancer burden in a population. It describes the number of new cases of cancer diagnosed in a given time period. It is often expressed as a rate per 100,000 people.
- Cancer risk in a population is related to many things in addition to age, such as:
- Prevalence of risk factors that include those that are modifiable (e.g., tobacco use, obesity or vaccine-preventable infections such as hepatitis B) and non-modifiable (e.g., reproductive and hormonal factors or genetics).
- Prevalence of protective behaviours, including uptake of human papillomavirus (HPV) vaccine.
- Cancer screening patterns (availability, type and uptake).
- Exposure to environmental or occupational carcinogens (such as asbestos).
- It can be difficult to link exposure to risk factors and cancer in the population, partly because cancer can develop at different rates after exposure. Lung cancer rates, for example, can take about 2 decades to reflect changes in provincial smoking rates. In contrast, rapid uptake of screening can result in an apparent sudden rise in cancer diagnoses because more cancers are discovered earlier than they otherwise would have been.
- Mortality describes the number of cancer deaths in a given time period. As with incidence, it often is expressed as a rate per 100,000 people. Mortality statistics are related to both incidence and survival.
- Mortality rates reflect the impact of factors that increase the risk of dying from cancer and of interventions that reduce this risk (such as screening and treatment).
- Cancer survival in a population describes the average prognosis over a given period of time after a cancer diagnosis. When survival of cancer patients is compared to the survival of the general population, it is called relative survival.
- Relative survival is a ratio that compares the survival experience of individuals with cancer to that of people of the same age and sex in the general population. It shows the extent to which cancer shortens life, and it is often age-adjusted when comparing survival ratios from different time periods. This is done to account for the fact that the risk of death increases as we age—and the Ontario population is aging.
- Prevalence describes the number of people in a population who are still alive on a given date. It includes those who were diagnosed within a given period of time (such as within the past 10 years) and those who have been recently diagnosed. Prevalence statistics depend on both incidence and survival.
Rates and ratios for incidence, mortality and survival are age-adjusted to allow comparison over time while accounting for changes in the age structure of the population.
See the corresponding methodology pages for more details on our analysis, as well as definitions of cancer.
What do the results show?
The number of new cancer cases diagnosed each year in Ontario has increased annually since 1981 (Figure 1).
- An aging population and population growth have contributed proportionally more new cases of cancer over the last 32 years than any changes in the risk of developing cancer (Figure 1).
- In 2018, an estimated 90,484 new cancer cases will be diagnosed, which is more than 3 times the number of new cancer cases in 1981 (29,650). Of the additional new cases, about half will be due to an aging population, about one-third will be due to a growing population and nearly one-tenth will be due to changes in cancer risk.
The most commonly diagnosed cancers in Ontario for males were prostate (20%), lung (13%) and colorectal (12%). For females, the most common cancers were breast (27%), lung (12%) and colorectal (10%) (Figures 2 and 3).
- The incidence rate for all cancers combined in males increased from 1981 to 2001. It then began to decline.
- For females, the incidence rate for all cancers combined has been increasing steadily since 1981 (Figure 4).
- Starting with 2010 diagnoses, the Ontario Cancer Registry rules for counting multiple primary cancers were changed to align the registry with the North American standard. This change has resulted in more cancer cases being counted for certain cancer types, but it does not necessarily reflect an increase in the number of people being diagnosed with cancer in the province. The impact of this change differs by cancer type, with some cancers (such as female breast) showing a particularly large increase in incidence rates, while others (such as colorectal and lung) show more modest increases (Figures 4 to 6).
Incidence rates for 3 of the most common cancers diagnosed in males in Ontario (prostate, lung and colorectal) are either stable or declining (Figure 5).
- The prostate cancer incidence rate has been declining since 2007. The peak in incidence in 1993 likely coincided with the introduction of prostate-specific antigen (PSA) testing in 1988.
- The lung cancer incidence rate has been stable since 2008.
- The colorectal cancer incidence rate has been declining since 1981.
Incidence rates for 3 of the most common cancers diagnosed in females in Ontario (breast, lung and colorectal) are increasing or declining in Ontario (Figure 6).
- Breast cancer incidence increased at 2% per year from the 1980s to the early 1990s. It then decreased annually from 1992 to 2012.
- The lung cancer incidence rate has been increasing since the 1980s, but the upward trend has been slowing since 1997.
- Colorectal cancer incidence in females is complex. The rate fell by 1.2% per year from 1982 to 1996, remained stable from 1996 to 1999, and then fell again from 1999 onwards. This reflects an increase in the rectal cancer incidence rate from 1996 to 1999, while the colon cancer incidence rate declined throughout the same period.
Mortality has been decreasing for both males and females for a number of years (Figure 7).
- The mortality rate for all cancers combined in males increased from 1981 to 1988. It has declined significantly from 1988 to 2013 (Figure 7).
- For females, the mortality rate for all cancers combined increased from 1981 to 1985. It then declined from 1985 to 2013 (Figure 7).
Mortality rates for 3 of the most common cancers diagnosed in males in Ontario (prostate, lung and colorectal) are declining (Figure 8).
- The prostate cancer mortality rate rose from 1981 to 1994. It then fell annually from 1994 to 2013.
- The lung cancer mortality rate began to level off in the late 1980s and has been declining ever since.
- The colorectal cancer mortality rate has been declining steadily since the early 1980s.
Mortality rates for 3 of the most common cancers diagnosed in females in Ontario (breast, lung and colorectal) are stable or declining in Ontario (Figure 9).
- The breast cancer mortality rate has been declining since 1986.
- The lung cancer mortality rate increased from 1981 to 2000. Since 2000, however, it has been declining annually.
- The colorectal cancer mortality rate declined from 1981 to 2013.
The 5-year relative survival ratio for most common cancers has improved in Ontario since 1999 (Figure 10).
- The improvements in survival are a result of advances in treatment and detection, including improvements in diagnostic technologies and the implementation of organized screening programs for some cancers.
- The exceptions to this improvement are uterus and bladder cancers, for which survival declined slightly but not significantly. Other jurisdictions (including Europe, South Australia and the United States) have recorded stable or decreasing trends for bladder cancer survival over similar time frames.
- Beginning in 2005, changes in pathology reporting led to more accurate identification of in situ bladder cases. These were subsequently removed from survival analyses, and survival for the remaining malignant cases is lower. Changes in the distribution of histologic subtypes for bladder cancer, which differ in their survival, may also be a contributor to the slight decline in the 5-year relative survival ratio for this cancer.
- In spite of improvements, relative survival remains low for cancers of the pancreas, lung and stomach, which are all less than 32%. This means that, compared to Ontarians of the same age and sex, the probability of surviving at least 5 years after a diagnosis of one of these cancers is reduced by more than 68%.
- The 5-year relative survival ratios for thyroid, prostate, female breast and melanoma cancers are high – 85% or higher. In particular, the 5-year relative survival ratios for thyroid and prostate cancers are 93% or higher.
Prostate and breast cancers have the highest 10-year prevalence (Figure 11).
- As of January 1, 2014, 75,634 men living in Ontario had been diagnosed with prostate cancer within the previous 10 years. During that same period, 71,355 women living in Ontario had been diagnosed with breast cancer. The prevalence for both of these cancers is high because of their high incidence and good survival rates.
- Although colorectal cancer is one of the most common cancers in Ontario, the 10-year prevalence for this cancer was only about 45,617 (as of January 1, 2014). This is a reflection that colorectal cancer has lower survival than breast and prostate cancers.
- Although lung cancer is one of the most common cancers diagnosed in Ontario, it ranks lower for prevalence than the less common cancers of thyroid and melanoma. This is due to the very poor survival for lung cancer compared with the high survival for thyroid cancer and melanoma.
- In spite of increasing cancer incidence, more effective treatments and early detection have resulted in more Ontarians surviving cancer with each passing year. As a result, many cancers are now being managed as chronic conditions.
Find out more
More information on cancer incidence, mortality, survival and prevalence in Ontario can be found in the Ontario Cancer Statistics Report, 2018.
Information on cancer statistics across Canada can be found in Canadian Cancer Statistics.