Avoidable cancer deaths globally

In this issue of CA: A Cancer Journal for Clinicians, Jemal et al describe the global burden of cancer. About 7.6 million people died from cancer in 2008 worldwide, and this number is projected to rise to 13.2 million deaths in 2030 simply due to the aging and growth of the population. Over 80% of the projected cancer deaths in 2008 are expected to be in lowand middle-income countries. A large body of epidemiologic evidence suggests that most cancer deaths are avoidable, although the exact percentages worldwide or for specific parts of the world are not known. In their seminal article in 1981, Doll and Peto estimated that about 75% of US cancer deaths could be attributed to lifestyle and other environmental factors that are in principle avoidable. In contrast, Danaei et al estimated that in 2005 about 35% of cancer deaths worldwide and 37% of the cancer deaths in high-income countries could be attributed to potentially modifiable risk factors. Using this estimate, about 2.6 million of the 7.6 million total cancer deaths that occurred in 2008 were potentially avoidable through prevention of major risk factors, including tobacco use, dietary factors, infections (specifically related unsafe sex [cervical cancer] and contaminated injections in health care settings [liver cancer]), and alcohol use. This translates to avoidance of about 7300 cancer deaths per day. Additional cancer control interventions that are not accounted for in this estimate are vaccinations against hepatitis B and human papillomavirus infections, human immunodeficiency virus (HIV) prevention and antiretroviral therapy for HIV-related cancers, and screening for breast and colorectal cancers. Tobacco use increases the risk of lung cancer as well as at least 15 additional sites and is the single most preventable cause of cancer death, accounting for 21% of the total cancer deaths (1.6 million deaths) worldwide. While tobacco consumption is decreasing in many economically developed countries, it is increasing in many economically developing countries. This century, about 80% of the 1.3 billion current smokers worldwide live in lowand middle-income countries, with over 300 million in China alone. Smokers in these countries are disproportionately younger, when the benefit of cessation in reducing deaths from lung cancer and other smoking-related diseases is the greatest. Smokers who quit before middle age avoid the majority of the excess risk because of the long delay between onset of smoking and death from smoking-related diseases, typically 30 to 50 years. Policies and programs known to increase cessation include raising the price of tobacco products, banning smoking in public places, restricting tobacco advertising and promotion, counter advertising, and providing treatment and counseling for tobacco dependence. In 2003, the World Health Organization (WHO) established the Framework Convention on Tobacco Control to combat the growing tobacco epidemic using these measures. Although an overwhelming majority of the WHO Member States (168) signed the treaty (available at: http://www.fctc.org), few have implemented the tobacco control policies or programs according to the framework. Given the early stage of the tobacco epidemic in many developing countries and the long delay between the peaks in tobacco consumption and lung cancer rates, developing countries have the unique opportunity to avoid millions of smokingrelated cancer deaths by implementing and enforcing comprehensive tobacco control programs. Unhealthy diet, physical inactivity, and obesity have been associated with an increased risk of several cancers, including breast, colorectal, stomach,