HPV infection

Cervical cancer is almost always caused by human papillomavirus (HPV) infection that is spread through sexual contact. There are more than 80 types of human papillomavirus and about 30 of these can infect the cervix. HPV types 16 and 18 are most often linked to cervical cancer.

Most of the time, the body’s immune system can fight the HPV infection before cancer forms. Only a very small number of women infected with HPV develop cervical cancer.

DES

Being exposed to a drug called diethylstilbestrol (DES) while in the mother’s womb increases the risk of cervical dysplasia and clear cell adenocarcinoma of the vagina and cervix. Between 1940 and 1971, DES was given to some pregnant women in the United States to prevent miscarriage (premature birth of a fetus that cannot survive) and premature labor.

Giving birth to many children

Among women who are infected with HPV, those who have had 7 or more full-term pregnancies have an increased risk of cervical cancer.

Using oral contraceptives for a long time

Among women who are infected with HPV, those who have used oral contraceptives (“the Pill”) for 5 to 9 years have a risk of cervical cancer that is 3 times greater than that of women who have never used oral contraceptives. The risk is 4 times greater after 10 or more years of use. In women who stop taking oral contraceptives, over a 10 year period, the risk of cervical cancer returns to that of women who never used oral contraceptives.

Smoking cigarettes

Among women who are infected with HPV, those who either smoke cigarettes or breathe in secondhand smoke have an increased risk of cervical cancer. The risk increases with the number of cigarettes smoked per day and how long the woman has smoked. Current and former smokers have 2 to 3 times the risk of cervical dysplasia and invasive cervical cancer.

Having a weakened immune system

Having a weakened immune system caused by immunosuppression increases the risk of HPV infection and cervical cancer. Immunosuppression weakens the body’s ability to fight infection and other diseases.

Immunosuppression can be caused by these and other conditions:

Women who are infected with the HIV virus or who take medicine to prevent organ rejection after transplant are less able to fight HPV infection and are at increased risk of cervical cancer.

Being sexually active at a young age or having many sexual partners

The risk of HPV infection is higher in women who become sexually active before age 18 and in women who have had 6 or more sexual partners.

Avoiding sexual activity

Nearly all cases of cervical cancer are caused by HPV infection, which is spread through sexual activity. Women who are not sexually active have almost no risk of cervical cancer.

Getting an HPV vaccine

Vaccines that protect against HPV infection greatly reduce the risk of cervical cancer. These vaccines do not protect women who are already infected with HPV.

Several HPV vaccines have been approved by the U.S. Food and Drug Administration (FDA). These vaccines have been shown to prevent infection with the types of HPV that cause most cervical cancers. Protection against HPV infection lasts for 6 to 8 years. It is not known if the protection lasts longer.

Harms of HPV vaccines include dizziness, feeling faint, headache, fever, and redness, tenderness, or warmth at the place of injection. Allergic reactions are rare. Getting the HPV vaccine while pregnant does not have a harmful effect on the pregnancy.

Using barrier protection during sexual activity

Some methods used to prevent sexually transmitted diseases (STDs) decrease the risk of HPV infection. The use of a barrier method of birth control, such as a condom or diaphragm, helps protect against HPV infection.