What Causes Cervical Cancer?

In recent years, scientists have learned a great deal about the changes that happen in the cells of the cervix when cancer develops. They have learned, for example, that certain changes, called mutations, in the structure and function of DNA (a chemical that carries the instructions for nearly everything our cells do) can make normal cells cancerous.

Scientists now believe that the human papillomavirus (HPV) causes the cells to produce two proteins known as E6 and E7. These proteins turn off some tumor suppressor genes (segments of DNA that slow down cell division or cause cells to die at the right time). This may allow the cervical lining cells to grow in an uncontrolled way, which in some cases leads to cancer.

But this does not completely explain what causes cervical cancer. Most women with HPV do not get cervical cancer, and other factors influence which women exposed to HPV are more likely to develop cervical cancer.

In addition to HPV, scientists have identified smoking and immune system deficiency as factors that play a role in causing cervical cancer. Cigarette smoke produces cancer-causing chemicals that damage the DNA of cervical cells. Infection with HIV (the AIDS virus) makes a woman's immune system (which fights infection) less able to fight HPV and early cervical cancers.

Risk Factors for Cervical Cancer 

Doctors and researchers believe that certain factors, known as risk factors, increase a person’s chances of getting cervical cancer. However, not everyone with a risk factor will develop cervical cancer. Also, people without risk factors can develop the disease.

Risk factors for cervical cancer include: 

• Age - Cervical cancer is most common in women over the age of 40. However, this disease can occur at any age.
• Diethylstilbestrol (DES) - DES is a drug that was prescribed between 1940 and 1971 for some women believed to be at increased risk of miscarriages. The risk of cervical cancer seems to be highest in women whose mothers took the drug during their first 16 weeks of pregnancy.
• Family history of cervical cancer - Cervical cancer seems to run in some families. If your mother or sister had cervical cancer, your chance of developing the disease is two or three times higher than average. This tendency may sometimes be caused by an inherited condition that makes some women less able to fight off HPV infection than others.
• Infection with chlamydia - Chlamydia, a relatively common kind of bacteria that can infect the female reproductive system, is spread by sexual contact. Some recent studies suggest that women with blood test results showing past or current chlamydia infection are at greater risk of cervical cancer than women with negative blood test results.
• Infection with the human papillomavirus (HPV) - The most important risk factor for cervical cancer is HPV infection. Scientists believe that only women who have been infected with this virus will develop cervical cancer, although most women with HPV do not develop cervical cancer.

HPVs are a group of more than 100 types of viruses. Some of these viruses can also cause warts, or papillomas, which are noncancerous (benign) tumors, while others, known as “high-risk” types of HPV, cause cervical cancer. HPV viruses are passed from person to person through sexual contact.

Certain types of sexual behavior increase a woman’s risk of being infected with HPV:

• Having sex at an early age
• Having many sexual partners
• Having a sexual partner who has had many sexual partners
• Having sex with uncircumcised males

• Low income - Many women with low incomes do not have good access to adequate health care services, including Pap tests, so they often do not get treated for precancerous cervical disease.
• Multiple pregnancies - Women who have had many full-term pregnancies have an increased risk of developing cervical cancer, possibly because they were exposed to HPV more often or because the hormonal changes during pregnancy could make them more susceptible to HPV infection or cancer growth.
• Oral contraceptives (birth control pills) - Long-term use of birth control pills (more than 5 years) appears to increase the risk of cervical cancer.
• Race/Ethnicity - Cervical cancer is more common among African-American, Hispanic, and Native American women.
• Smoking - Women who smoke are about twice as likely as nonsmokers to get cervical cancer. Smoking exposes the body to many cancer-causing chemicals that are absorbed by the lungs and carried in the bloodstream throughout the body. Tobacco byproducts have been found in the cervical mucus of women who smoke. These substances apparently damage the DNA of cells in the cervix and may contribute to the development of cervical cancer.
• Weakened immune system - Women with HIV (the virus that causes AIDS) infection or who take drugs that suppress the immune system have an increased risk of developing cervical cancer.
• Weight - Some studies show that women who are overweight are more likely to get cervical cancer.

This content has been reviewed and approved by Myo Thant, MD.