When you get a diagnosis of cancer, it's natural to wonder what may have caused the disease. Doctors cannot always explain why one woman develops cervical cancer and another does not. However, we do know that a woman with certain risk factors may be more likely than others to develop cervical cancer. A risk factor is something that may increase the chance of developing a disease.

Studies have found a number of factors that may increase the risk of cervical cancer. For example, infection with HPV (human papillomavirus) is the main cause of cervical cancer. HPV infection and other risk factors may act together to increase the risk even more:

• HPV infection: HPV is a group of viruses that can infect the cervix. An HPV infection that doesn't go away can cause cervical cancer in some women. HPV is the cause of nearly all cervical cancers.
  
  HPV infections are very common. These viruses are passed from person to person through sexual contact. Most adults have been infected with HPV at some time in their lives, but most infections clear up on their own.
  
  Some types of HPV can cause changes to cells in the cervix. If these changes are found early, cervical cancer can be prevented by removing or killing the changed cells before they can become cancer cells. The NCI fact sheet Human Papillomaviruses and Cancer: Questions and Answers ¹ has more information.
  
  A vaccine for females ages 9 to 26 protects against two types of HPV infection that cause cervical cancer. The NCI fact sheet Human Papillomavirus (HPV) Vaccines: Questions and Answers ² has more information.
  
  
• Lack of regular Pap tests: Cervical cancer is more common among women who don't have regular Pap tests. The Pap test helps doctors find abnormal cells. Removing or killing the abnormal cells usually prevents cervical cancer.
  
  
• Smoking: Among women who are infected with HPV, smoking cigarettes slightly increases the risk of cervical cancer.
  
  
• Weakened immune system (the body's natural defense system): Infection with HIV (the virus that causes AIDS) or taking drugs that suppress the immune system increases the risk of cervical cancer.
  
  
• Sexual history: Women who have had many sexual partners have a higher risk of developing cervical cancer. Also, a woman who has had sex with a man who has had many sexual partners may be at higher risk of developing cervical cancer. In both cases, the risk of developing cervical cancer is higher because these women have a higher risk of HPV infection.
  
  
• Using birth control pills for a long time: Using birth control pills for a long time (5 or more years) may slightly increase the risk of cervical cancer among women with HPV infection. However, the risk decreases quickly when women stop using birth control pills.
  
  
• Having many children: Studies suggest that giving birth to many children (5 or more) may slightly increase the risk of cervical cancer among women with HPV infection.
  
  
• DES (diethylstilbestrol): DES may increase the risk of a rare form of cervical cancer in daughters exposed to this drug before birth. DES was given to some pregnant women in the United States between about 1940 and 1971. (It is no longer given to pregnant women.)

Having an HPV infection or other risk factors does not mean that a woman will develop cervical cancer. Most women who have risk factors for cervical cancer never develop it.

Glossary Terms

A disease caused by the human immunodeficiency virus (HIV). People with AIDS are at an increased risk for developing certain cancers and for infections that usually occur only in individuals with a weak immune system. Also called acquired immunodeficiency syndrome.

A synthetic form of the hormone estrogen that was prescribed to pregnant women between about 1940 and 1971 because it was thought to prevent miscarriages. Diethylstilbestrol may increase the risk of uterine, ovarian, or breast cancer in women who took it. It also has been linked to an increased risk of clear cell carcinoma of the vagina or cervix in daughters exposed to diethylstilbestrol before birth. Also called DES.

The cause of acquired immunodeficiency syndrome (AIDS). Also called human immunodeficiency virus.

A type of virus that can cause abnormal tissue growth (for example, warts) and other changes to cells. Infection for a long time with certain types of human papillomavirus may cause cervical cancer. Human papillomavirus may also play a role in some other types of cancer. Also called HPV.

The complex group of organs and cells that defends the body against infections and other diseases.

Invasion and multiplication of germs in the body. Infections can occur in any part of the body and can spread throughout the body. The germs may be bacteria, viruses, yeast, or fungi. They can cause a fever and other problems, depending on where the infection occurs. When the body’s natural defense system is strong, it can often fight the germs and prevent infection. Some cancer treatments can weaken the natural defense system.

Something that increases the chance of developing a disease. Some examples of risk factors for cancer are age, a family history of certain cancers, use of tobacco products, being exposed to radiation or certain chemicals, infection with certain viruses or bacteria, and certain genetic changes.

In medicine, a very simple microorganism that infects cells and may cause disease. Because viruses can multiply only inside infected cells, they are not considered to be alive.