Lung cancer is the leading cause of cancer deaths among Ontario women In order of rank, the five most common causes of cancer death in Ontario females are lung, breast, colon and rectum, pancreas and ovary. Survival for lung cancer is poor, mainly because there are no effective screening procedures and its symptoms are non- specific. Tobacco use is a key risk factor for lung and several other cancers. Almost 3,000 Ontario women died of lung cancer in 2008, making it the leading cause of cancer death among females in the province. This disease is highly fatal, mainly because there are no effective ways to screen for it. Its symptoms also tend to be non-specific and appear when the cancer is already in a late stage, so by the time many people are diagnosed, treatment is less likely to work. The five-year relative survival rate for lung cancer remains low, at less than 20%.1 After lung, cancers of the breast (1,888), colon and rectum (1,433), pancreas (676) and ovary (601) represent the second, third, fourth and fifth most common causes of cancer deaths in Ontario females. The chances of surviving breast and colorectal cancers are, however, substantially higher than the chances of surviving lung cancer. Although pancreatic cancer is rare, it’s the most fatal cancer in Ontario, with the poorest five-year survival rate.2 Like lung cancer, ovarian cancers tend to be diagnosed at an advanced stage, making them hard to beat. The most important risk factor for developing lung cancer is tobacco use, accounting for an estimated 86% of lung cancer cases in high-income countries like Canada.3 Smoking is also a risk factor for several other cancers, including colorectal, pancreatic and probably breast cancer.4   The best way to prevent lung and other cancers related to smoking is to avoid smoking and being exposed to second-hand smoke. The Ontario government has made it a priority to reduce cigarette smoke exposure through its Smoke-free Ontario Act, which restricts the public display of tobacco products, bans smoking in motor vehicles with children under the age of 16 and prohibits smoking in enclosed public spaces, such as the workplace (http://www.mhp.gov.on.ca/en/smoke-free/default.asp). References Cancer Care Ontario/Cancer System Quality Index 2011. Cancer in Ontario. Figure 4. Age-standardized 5-year relative survival ratio* for 14 common cancers, Ontario, 1993-1997 vs 2003-2007. Available at http://www.csqi.on.ca/cms/one.aspx?portalId=89621&pageId=89815. Cancer Care Ontario. Cancer Fact: The most fatal cancers in Ontario. April 2011. Available at http://www.cancercare.on.ca/cancerfacts/. Danaei G, Vander Hoorn S, Lopez AD, Murray CJL, Ezzati M, and the Comparative Risk Assessment collaborating group (Cancers). Lancet 2005; 366:1784–93. Secretan B, Straif K, Baan R, et al. A review of human carcinogens – Part E: tobacco, areca nut, alcohol, coal smoke, and salted fish. Lancet Oncol 2009;10:1033–4. Citation: Cancer Care Ontario. Cancer Fact: Lung cancer is the leading cause of cancer deaths among Ontario females. January 2012. Available at http://www.cancercare.on.ca/cancerfacts. Prepared by staff in Prevention and Cancer Control.