1. Prepared by staff in Prevention and Cancer Control.
Lung cancer accounts for largest proportion of premature Ontario cancer deaths (Dec. 2012)
Cancer is responsible for the largest proportion of premature mortality in Ontario.
Lung cancer is the leading cause of premature death due to cancer because it is common in the Ontario population and has poor survival.
Less common cancers that occur at young ages and/or are highly fatal also contribute significantly to premature mortality due to cancer.
In 2009, lung cancer was responsible for the largest proportion of premature cancer deaths in Ontario, accounting for 25% or 95,013 potential years of life lost (PYLL*). Colorectal cancer accounted for the second largest proportion of premature cancer deaths (11% or 41,769 PYLL), followed by female breast cancer (9% or 34,686 PYLL). Cancer overall was the leading cause of premature death, at 386,018 PYLL, accounting for nearly 33% of premature mortality from all causes.
Potential years of life lost is influenced by how common a cancer is, the average age at diagnosis, and how likely it is for that cancer to be fatal. In Ontario, lung cancer accounts for by far more PYLL than any other cancer because it is one of the most common cancers diagnosed and has very poor survival, as it is often diagnosed at advanced stages. The other three most commonly diagnosed cancers — prostate, breast, and colorectal — are also leading causes of premature death because they affect a large number of people. However, they are responsible for fewer PYLL than lung cancer since they are less fatal. This is particularly true for prostate cancer, which ranks eighth in terms of PYLL despite accounting for the highest number of cancer cases diagnosed in Ontario, since, on average, the chances of surviving it are very good.  
Cancers that are less common but frequently occur at young ages or have very poor survival may also have high PYLL. Pancreatic cancer, for example, is relatively rare, but is highly fatal, so it is responsible for more years of potential life lost than several more common cancers, including prostate. Similarly, leukemia and cancers of the brain, stomach and ovary are relatively rare, but rank among the leading causes of premature death from cancer because their age of onset is early (particularly for leukemia) and/or their survival is poor. Although liver cancer is relatively rare, it has recently become a bigger contributor to premature cancer mortality in Ontario because its incidence rate has been rising and its survival has remained poor.1
A large portion of the premature deaths due to cancer, particularly common cancers, such as lung and colorectal, can be avoided by modifying behaviours such as tobacco use and lack of physical activity.2 This leaves great potential for reducing PYLL for several cancers through prevention efforts.
*Potential years of life lost (PYLL) is a measure of the additional years a person dying from cancer would have lived had he or she experienced the life expectancy of the population.
References
Cancer Care Ontario. Cancer Fact: Liver cancer shows striking geographic pattern. February Available at
Cancer Care Ontario, Ontario Agency for Health Protection and Promotion (Public Health Ontario). Taking action to prevent chronic disease: recommendations for a healthier Ontario. Toronto: Queen’s Printer for Ontario; 2012.
Citation: Cancer Care Ontario. Cancer Fact: Lung cancer accounts for largest proportion of premature Ontario cancer deaths. December Available at
Prepared by staff in Prevention and Cancer Control.