Lung cancer mortality differences between men and women influenced by smoking trends (Apr. 2015) Trends in lung cancer mortality rates reflect past trends in smoking rates for men and women in Ontario. The uptake of smoking began much later in women than men, and as a result smoking rates and lung cancer mortality rates in women peaked nearly 20 years after these rates peaked in males. Smoking remains the most important risk factor for lung cancer in Ontario. To reduce the burden of lung cancer, prevention efforts addressing smoking and tobacco will need to be sustained over the long term. Changes over time in smoking rates have led to different peaks in lung cancer mortality for men and women. In men, the rate of smoking increased rapidly from the 1930s to the 1950s, peaking at roughly 50 per cent in the early 1960s. Because lung cancer takes a long time to develop, mortality rates among men didn’t begin increasing until the 1950s and peaked at roughly 77 per 100,000 in the 1980s. However, smoking became popular much later among women than men, with female smoking rates being very low before the 1940s and not reaching their peak until the late 1970s — nearly 20 years after smoking rates peaked in men. As a result, mortality rates in women didn’t begin rising steadily until the 1960s and they peaked in the late 1990s (at a rate of roughly 33 per 100,000) before stabilizing. By the early 2000s, smoking rates in men were declining more gradually and stabilized at nearly half of the peak rate (at 26 per cent) by 2005. Male mortality followed suit, declining from 1989 onwards. In women, smoking rates declined throughout the 1980s, 1990s, and 2000s, falling to nearly half of the peak rate by 2010 (17 per cent). Lung cancer is the most common cause of cancer death among men and women in Ontario, accounting for 6,580 deaths in 2011. The reason so many people die from lung cancer is that it is both common and highly fatal. It is often diagnosed at advanced stages and has a five-year relative survival of less than 20 per cent. Therefore, any changes in lung cancer mortality rates in Ontario are mostly due to changing incidence rates (new cases), as opposed to changes in survival. There is currently no organized screening program for lung cancer in Ontario, making the best strategy for lowering mortality rates to reduce the number of people who develop this disease through prevention efforts. Smoking is the most important risk factor for lung cancer and is estimated to account for over 70 per cent of new cases in Ontario.1 This means that over 70 per cent of lung cancer cases could be prevented if everyone in Ontario stopped smoking. The change in lung cancer mortality following reduced smoking rates shows how essential prevention efforts are in decreasing the burden of lung cancer in the province. Because lung cancer develops many years after someone is exposed to tobacco smoke, future prevention efforts will need to be sustained over the long term to have a meaningful impact on lung cancer burden. For more information, see: • Diesel engine exhaust causes almost 200 work-related lung cancers annually in Ontario (January 2015 Cancer Fact). Available at http://www.cancercare.on.ca/cms/one.aspx?portalId=1377&pageId=327046. • Smoking responsible for a large proportion of new cancer cases in Ontario (January 2014 Cancer Fact). Available at http://www.cancercare.on.ca/cms/one.aspx?portalId=1377&pageId=294768. References 1. Cancer Care Ontario. Cancer Risk Factors in Ontario: Tobacco. Toronto, Canada, 2014. Citation: Cancer Care Ontario. Cancer Fact: Lung cancer mortality differences between men and women influenced by smoking trends. April 2015. Available at http://www.cancercare.on.ca/cancerfacts. Prepared by staff in Prevention and Cancer Control.