Introduction

Cancer is one of the most feared diseases. Some types of cancer can be treated successfully in older people; a true cure—or at least a very prolonged remission—can sometimes be achieved. Thus, a diagnosis of cancer is not necessarily an imminent death sentence. Even when cancer is advanced, most symptoms usually can be effectively managed, although it remains true that most older people with advanced cancer will die from their cancer.

A cancer is a group of cells (usually coming from a single cell) that has uncontrolled growth. Healthy cells are transformed into cancerous cells in a complex way. The first step is called initiation, in which a change in the cell's genetic material sets the stage for the cell to become cancerous. Initiation may be caused by any number of cancer-causing agents (carcinogens), such as tobacco, radiation, or chemicals. The second step, called promotion, allows a cell that has been initiated to become cancerous. Promotion may be caused by substances in the environment.

Cancer can begin anywhere in the body, but certain cancers are more common than others. Cancer can also develop at any age but is much more common in older people. Over half of all cancer diagnoses and half of cancer deaths occur in people over age 65. Lung, breast, prostate, and colon cancer are especially common in older people.

Cancer is more common in older people for a number of reasons. The longer people are alive, the longer they are exposed to cancer-causing agents. The cells of the immune system, which help protect against cancer, become less active with increasing age. Also, the body's ability to repair damage to genetic material inside the cell declines with aging, allowing for more opportunities for cancer cell initiation. Yet, there is evidence that certain types of cancer are less aggressive in older people.

Cancers harm people in a number of ways. As cancers grow, they may invade and damage nearby parts of the body. Cancers may also interfere with the function of organs and tissues simply by pressing up against them. They can spread to distant tissues, producing collections of cells (called metastases) that may invade and damage tissues and blood vessels in these new areas. Cancers can also produce hormones or similar chemical substances, which can travel through the bloodstream to cause unwanted effects throughout the body.

See the table Talking About Cancer.