Risk Factors
Anyone can develop cancer. However, the risk of being diagnosed with cancer increases with age. In economically developed countries, 78% of all newly diagnosed cancer cases occur at age 55 and older, compared with 58% in developing countries. The difference is largely due to variations in age structure of the populations. The populations of developing
countries are younger and have a smaller proportion of older individuals in whom cancer most frequently occurs.
Nex table 4 shows the lifetime risk of developing or dying from various types of cancer before age 65 by sex and level of economic development in 2002. The risk of developing any form of cancer is nearly twice as high in economically developed countries as in economically developing countries in both men (14.8% vs. 8.5%) and women (13.1% vs. 8.1%). In contrast, the risk of dying before age 65 from cancer is similar between developed and developing countries (7.2% vs. 6.1% in men and 4.8% vs. 4.9% in women). These differences relate to variations in the type of major cancers and to the availability of early detection and treatment services between economically developed and developing countries.
Definition of Risk in Cancer:
The term “risk” is used in two common ways: lifetime risk or relative risk. Lifetime risk refers to the probability that an individual will develop or die from cancer over the course of a lifetime. For example, the lifetime risk of developing some type of invasive cancer among men in the United States is 45%. Relative risk is a measure of the strength of the association between a risk factor and a particular type of cancer. It compares the risk of developing cancer in persons with a certain exposure or trait to the risk in persons who do not have this characteristic. For example, male smokers are about 23 times more likely to develop lung cancer than nonsmokers, thus their relative risk is 23. Most relative risks are not this large. For example, women who have a first-degree relative (mother, sister, or daughter) with a history of breast cancer have about
twice the risk of developing breast cancer compared to women who do not have a family history.
Lifetime Probability (%) of Developing or Dying from Cancer Before Age 65 by Sex, CancerSite, and Level of Economic Development, 2002
