Risk factors for cervical cancer
A risk factor is something that increases the risk of developing cancer. It could be a behaviour, substance or condition. Most cancers are the result of many risk factors. Infection with the human papillomavirus (HPV) is the main risk factor for cervical cancer, but it does not always cause the disease by itself. We now know that other risk factors (co-factors) act along with HPV to increase the risk for cervical cancer.
Most cases of cervical cancer occur in women younger than 50 years of age. Cervical cancer tends to affect women of African ancestry more often than Caucasian women. Women of certain religions (for example, Catholic nuns and Amish and Mormon women) also tend to have lower rates of cervical cancer. This is likely due to having fewer sexual partners, which can lower their exposure to HPV.
Women with lower incomes and women with less education have a higher risk for cervical cancer. This may be because women in these groups do not have regular cervical screening or have other risk factors, such as higher rates of smoking.
Precancerous conditions of the cervix include squamous intraepithelial lesions (SILs). This isn’t cancer, but it can sometimes become cervical cancer if it isn’t treated. Some of the risk factors for cervical cancer may also cause these precancerous conditions. Find out more about precancerous conditions of the cervix.
Risk factors are generally listed in order from most to least important. But in most cases, it is impossible to rank them with absolute certainty.
There is convincing evidence that the following factors increase your risk for cervical cancer.
Most women who develop cervical cancer have had an HPV infection. But having an HPV infection doesn’t mean that you will develop cervical cancer. Many different types of HPV can infect the cervix, but only some of them cause abnormal changes to cells that may turn into cancer.
Find out more about human papillomavirus (HPV).
Being sexually active means more than just having intercourse with someone. It can mean:
- any genital skin-to-skin contact
- having oral sex
All women who have ever been sexually active are at risk for developing cervical cancer. This is because sexual activity potentially exposes you to HPV. Women who have never been sexually active rarely develop cervical cancer.
Becoming sexually active at a young age can increase the risk for cervical cancer. Researchers think this increased risk is because the cervix changes during puberty. These changes make the area more vulnerable to damage.
Certain types of sexual behaviour increase a woman’s risk of infection with HPV. Having intercourse with many partners can increase exposure to HPV, which is transmitted by sexual contact. For this reason, having many sexual partners is linked with a higher risk of cervical cancer. But a woman can have HPV even when she has had only one sexual partner.
Women also seem to be at a higher risk for developing cervical cancer if their male partners have had many sexual partners or female partners with cervical cancer.
Smoking increases the chance of an HPV infection not going away on its own. If an HPV infection doesn’t go away, it can lead to the development of SIL, which is a precancerous condition of the cervix, and cervical cancer.
Parity is the number of times a woman has given birth. Multiparity, or giving birth more than once, has been linked with a higher risk for cervical cancer in women with an HPV infection. The more children a woman gives birth to, the greater her risk for cervical cancer. But there isn’t a specific number of births that increases the risk.
We don’t yet fully understand how giving birth increases the risk for cervical cancer. It may be because of changes in hormones during pregnancy, or the trauma to the cervix during birth. Some research has suggested that women who have caesarean sections do not have a higher risk of developing cervical cancer.
The human immunodeficiency virus (HIV) weakens the immune system. A weakened immune system increases the risk of getting other infections, including HPV. Having a weakened immune system also increases the chances that an HPV infection won’t go away. HIV increases the risk that precancerous changes to the cells in the cervix can develop into cervical cancer.
Women who are HIV positive have a higher risk for cervical cancer, and precancerous cells change to cervical cancer faster in HIV-positive women than in HIV-negative women.
Chlamydia trachomatis is a type of bacteria. It is spread by sexual contact and can infect a woman’s genital tract. Women with both HPV and chlamydia infections have a higher risk for cervical cancer. Researchers think that long-term inflammation caused by chlamydia makes it harder for the body to clear the HPV infection, especially with repeated chlamydia infections.
Herpes simplex virus type 2 is also called human herpesvirus 2 or HHV-2. Infection with this virus may also be linked with a higher risk of developing cervical cancer in women with HPV.
Oral contraceptives are commonly called the pill. Taking oral contraceptives over a long time may increase the risk of an HPV infection developing into cervical cancer. This risk does not appear to be related to having an HPV infection. Women who take oral contraceptives for more than 5 years appear to have the highest risk for cervical cancer. This risk goes down over time after you stop taking oral contraceptives. After 10 years of not taking them, your risk for cervical cancer is no longer high.
Diethylstilbestrol (DES) is a form of estrogen. It was used between 1940 and 1971 to treat women with certain problems during pregnancy, such as miscarriages. It has not been approved for use in pregnant women since the 1970s.
Daughters of women who took DES during their pregnancy have a higher than average risk of developing a rare type of cervical cancer called clear cell carcinoma. Some studies also suggest that daughters of women who took DES may have a higher risk of developing precancerous changes of the cervix and squamous cell carcinoma (SCC) of the cervix.
Possible risk factors
Using immunosuppressant drugs is a possible risk factor for cervical cancer. This means that it has been linked with cervical cancer, but there is not enough evidence to show for sure that it is a risk factor.
There is some evidence that these drugs may increase the risk for cervical cancer in women who have received an organ transplant. The evidence for women taking immunosuppressant drugs for immune disorders like systemic lupus erythematosus or inflammatory bowel disease (ulcerative colitis or Crohn’s disease) is inconclusive.
Questions to ask your healthcare team
To make the decisions that are right for you, ask your healthcare team questions about risks.
A long-term (chronic) disease that causes inflammation of the connective tissues in the body. SLE increases the risk of lung cancer and non-Hodgkin lymphoma.
Also called lupus.
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Nearly 1 in 2 Canadians is expected to be diagnosed with cancer in their lifetime.