The American Cancer Society (ACS) estimates that nearly 1.5 million new cases of cancer will be diagnosed in the United States in 2007. Age is a primary risk factor for the disease with about 77 percent of all cancers being diagnosed in people age 55 and older. As of 2004, there were approximately 10.8 million men and women living with a history of cancer.

The association between age and an increased risk of cancer is not well understood. Certain changes in the cells cause cancer to begin, but scientists cannot explain the reasons for the process. Despite several theories, there is no definitive explanation for why cancer occurs more frequently in the older population.

Researchers continue to explore the association between aging and cancer risk. Meanwhile, healthcare providers urge people to undergo various cancer screening procedures as they grow older. The ACS has established age and frequency guidelines for various tests that can help screen for cancer in people at average risk of getting the disease.  

Age is a primary risk factor for cancer. According to the American Cancer Society (ACS), 77 percent of all cancers are diagnosed in people age 55 and older. Approximately one out of every two American men and one out of every three American women will get cancer in their lifetime.

Some cancers such as childhood leukemia, Wilms tumor, neuroblastoma and retinoblastoma are more common in children. However, as a general rule, most cancers become more commonplace as people grow older.

Cancer begins with an abnormal cell that divides to become two abnormal cells. Those cells then double again, becoming four abnormal cells. This division continues to produce a clinically significant tumor. The doubling process may occur quickly over weeks or may take place more slowly over extended periods that can last for years.

Before the initial cell becomes cancerous, it has to undergo a number of genetic mutations. In some cases, these changes occur spontaneously as a cell is dividing. In other cases, a cell is damaged by some substance, or carcinogen, and passes those changes on to its “daughter” cells when it divides.

These changes can take a long time to unfold, which means they usually do not manifest until a person is older. In addition, the longer a person lives, the greater the chance that the person will develop such genetic mistakes in the cells that are not easily repaired by the body. Many scientists believe this fact is responsible for the increasing incidence of cancer as a person ages.

However, other scientists argue that the cellular genetic changes alone are not sufficient to trigger cancer. In addition, there is some evidence that a person’s odds of getting cancer peak between ages 80 and 94, and then level off or actually decline.

Scientists are still trying to understand and explain the precise link between aging and cancer risk at a time when American society is growing older. The number of individuals age 65 and older is expected to double from 35 million to 70 million by 2030. For all cancers combined, people 65 and older have an incidence rate 10 times greater than that of younger people, according to the National Cancer Institute (NCI). The mortality rate for older cancer patients is also 16 times greater than that of their younger counterparts.

Cancers that are more common with advanced age include:

• Breast cancer. After non-melanoma skin cancers, breast cancer is the most common form of cancer in women and the second deadliest. Although rare, men can also develop breast cancer. The odds of a woman being diagnosed with breast cancer steadily increase with age. For example, the odds of breast cancer are 1 in 2,000 at age 30, but 1 in 28 by age 60, according to the NCI. It is estimated that 4 out of every 100 women who are 40 years old today will get breast cancer by the age of 60.
  
  
• Ovarian cancer. An overgrowth of malignant cells in one or both of a woman’s ovaries, which are part of the reproductive system. Ovarian cancer is the eighth leading cancer among women (excluding non-melanoma skin cancers) and accounts for more deaths than any other form of female reproductive system cancer. The majority of ovarian cancers develop after menopause with half of all ovarian cancers affecting women over age 63.
  
  
• Prostate cancer. This cancer of the prostate gland is the most frequently diagnosed cancer in men (aside from non-melanoma skin cancer) and the third leading cause of death among men. The prostate gland is a walnut-size male gland located below the urinary bladder and in front of the rectum. The risk of prostate cancer increases with age, especially after 50. More than 70 percent of prostate cancer is diagnosed in men over age 65, according to the U.S. Centers for Disease Control and Prevention (CDC). The median age at diagnosis is 72.
  

• Skin cancer. The most common of all cancers in the United States, accounting for as much as half of all cancer diagnoses, according to the ACS. Skin cancer is divided into two main categories, melanoma and non-melanoma. Non-melanoma is far more common and less deadly than its counterpart. The NCI estimates that approximately half of all Americans who live to age 65 will be diagnosed with some type of skin cancer.
  
  
• Stomach cancer. Also called gastric cancer, stomach cancer is characterized by cancerous (malignant) cell growth that begins in the cells of the stomach and invades the surrounding healthy cells. Stomach cancer is the second leading cause of cancer deaths worldwide. This cancer is far less common in the United States than in less developed countries and continues to decline. Two-thirds of cases are in people over 65 years old. 
  
  
• Lung cancer. The leading cause of cancer deaths in the United States and around the world. About 87 percent of lung cancers are due to tobacco products, either through direct smoking or exposure to second-hand smoke, according to the ACS. Lung cancer is rarely seen in patients under 40. Cases begin to increase after 45 and rise even more after 65. The NCI estimates that 2 percent of women and 3 percent of men will develop lung cancer between 50 and 70 years of age.
  
  
• Oral cancer. Also known as lip and mouth cancers, these are a group of diseases in which malignant cells are found in the tissues of the lip and mouth. The mouth or oral cavity includes the lips, inside of the mouth, gums, teeth and tongue. The pharynx is space behind the mouth that serves as the passageway from the nose to the top of the trachea (windpipe) and the esophagus (tube that goes to the stomach). More than half of all patients diagnosed with oral and oropharyngeal cancer are over the age of 65. 
  
  
• Head and neck cancer. Occur in various tissues and cavities in the head and neck region. Most head and neck cancers begin in the squamous or scale-like cells that line the mucous membranes in the head and neck. These surfaces include the lining of the nose, mouth and throat. Approximately 50 percent of all cases affect individuals over the age of 65. 

Based on ACS statistics released in 2004, the probability of developing invasive cancers over a person’s lifespan is:

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about age and cancer risk:

1. Based on my history and health, which cancers am I at greatest risk to develop?
   
   
2. What cancer screening tests should I undergo?
   
   
3. At what age should I begin these tests?
   
   
4. How does my family history affect my screening tests and schedule?
   
   
5. Are there any tests that can help predict which cancers are most likely to affect me as I age?
   
   
6. Should I consider any genetic testing for cancer?
   
   
7. How will developing one cancer affect my risk for other cancers?
   
   
8. Should I see any specialists on a regular basis?
   
   
9. What is the next step if cancer is detected in a screening test?
   
   
10. What is the best way to maintain records of my screening tests and results?