While there are many factors that put women at risk for cervical cancer, almost all cervical cancers are caused by the human papillomavirus (HPV), the same virus responsible for genital warts. There are over 100 different types of HPV. However, only certain types are associated with cervical cancer. These are called the high-risk types. High-risk types of HPV include:
- HPV 16
- HPV 18
- HPV 31
- HPV 33
- HPV 45
According to the American Cancer Society (ACS), approximately two thirds of all cervical cancers are caused by HPV 16 and 18. However, both types are preventable by vaccination. Also, not all infections with these types of HPV cause cervical cancer. Most women clear HPV infections on their own within two years.
Infections that last longer than a few years are called persistent infections. These are the infections most likely to become cancerous. It is not well understood why some women clear their HPV infections while others do not.
HPV is extremely common. According to the Centers for Disease Control and Prevention (CDC), six million people in the United States acquire HPV each year. At least 20 million already have it, and more than half of all sexually-active adults will be infected during their lifetime.
Fortunately, the two types of HPV responsible for most cases of cervical cancer can be prevented by vaccination. The two types responsible for most cases of genital warts are also preventable by vaccination. However, vaccination is most effective when it is done before sexual activity begins.
The risk of HPV infection can also be reduced by practicing safe sex.
HPV is transmitted during sex. It can be spread through:
- vaginal sex
- oral sex
- anal sex
Safe sexual practices can reduce the risk of transmission. Condoms should be used for vaginal and anal sex. Condoms or dental dams can also reduce the risk of virus transmission during oral sex. However, condoms cannot prevent HPV entirely. The virus spreads by skin-to-skin contact.
Sexually transmitted HPV has been linked to:
- cervical cancer
- anal cancer
- vulvar cancer
- throat cancer
Consistently practicing safe sex lowers your risk of developing an HPV-related cancer.
Certain genetic and lifestyle factors may increase a woman’s risk for contracting HPV, which can lead to cervical cancer. They include:
- first intercourse at a young age
- high number of sex partners
- a history of other sexually transmitted infections, such as chlamydia or gonorrhea
- sex with a man whose partner had cervical cancer
It is important to note that other biological factors also affect HPV infection. In young women, the cervix is more susceptible to infection. Smoking makes HPV infection more likely to turn into cancer. Immunodeficiency (weakened immune system) also makes it harder for the body to eliminate an HPV infection.
However, not all HPV infections lead to cervical cancer. While the exact cause is unknown, factors that may increase your risk for cervical cancer include:
- more than three full-term pregnancies, or a full-term pregnancy before the age of 17
- a family history of cervical cancer
- long-term use (more than 5 years) of oral contraceptives
- chlamydia infection
Having a mother who used a hormonal drug called diethylstilbestrol (DES) during pregnancy also increases cervical cancer risk. However, DES daughters are a special case. Their cancers are not necessarily caused by HPV. They start in a different type of cells than most cervical cancers.
Vaginal cancers are more common than cervical cancers in DES daughters.