Cervical cancer
Description
An in-depth report on the causes, diagnosis, treatment, and prevention of cervical cancer.
Alternative Names
Dysplasia; Human papillomas virus; Pap smear
Risk Factors
According to the American Cancer Society, nearly 10,000 new cases of invasive cervical cancer will be diagnosed in the U.S. in 2006. However, the number of new cervical cancer cases has been declining steadily over the past decades. Fifty percent of cervical cancer diagnoses occur in women between 35 and 55 years of age, and slightly more than 20% occur in women over 65 years of age.
Some women (15%) develop cervical cancer before the age of 30. Although cervical cancer is rare in women under age 20, there has been an increase in cancer rates in younger women. Many young women are infected with multiple types of HPV, which can increase their risk of getting cervical cancer. If young women with early abnormal changes do not have regular examinations, they are at high risk for localized cancer by the time they are age 40 and for invasive cancer by age 50.
Although it is the most preventable type of cancer, cervical cancer is ranked as the second most common cause of female death. Each year it kills an estimated 3,700 women in the U.S. and nearly 300,000 women worldwide.
In the United States, cervical cancer mortality rates plunged by 74% between 1955 and 1992 thanks to increased screening and early detection with the Pap test.
Socioeconomic and Ethnic Factors
Although the rate of cervical cancer has declined in both Caucasian and African American women over the past decades, it remains much more prevalent in African Americans and their death rates are twice as high as Caucasian women. Hispanic American women have more than twice the risk of invasive cervical cancer as Caucasian women also due to a lower rate of screening.
These differences, however, are almost certainly due to social and economic differences. Numerous studies report that high poverty levels are linked with low screening rates. In addition, lack of health insurance, limited transportation, and language difficulties hinder poor women’s access to screening services. Researchers are investigating programs that provide screening and treatment for women with abnormal Pap smears in a single visit. A 2001 study of women in the military found no differences in mortality rates when there is equal access to the same treatments.
Specific Risk Factors for Human Papillomavirus
The human papillomavirus (HPV) is the primary cause of cervical cancer. Between 12 - 46% of American women carry the virus. The risk for cervical cancer in infected women appears to be highest in those infected with HPV for more than 6 months. In most people, the virus goes away within a year. However, it persists in about 10% of infected women.
High Sexual Activity.
In adults, the most important risk factor for HPV is sexual activity with an infected person. Women most at risk for cervical cancer are those with a history of multiple sexual partners, sexual intercourse at 17 years or younger, or both. A woman who has never been sexually active has a very low risk for developing cervical cancer. Sexual activity with multiple partners increases the likelihood of many infections in addition to human papillomavirus.
Douching.
Women who douche on a weekly basis are more likely to contract cervical cancer than those who do not. Douching may destroy the natural antiviral substances normally present in the vagina, making women more susceptible to HPV.
Pessaries.
Use of a pessary (a ring-shaped plastic device that keeps the vagina and uterus from collapsing) increases the risk of chronic inflammation and viral infection at the insertion site and therefore may increase the risk for cervical cancer.
Risk Factors for HPV in Children and Infants.
HPV also can occur in children and even newborns. The virus may also be transmitted by an infected mother. In children, HPV is usually the harmless form that cause skin warts.
Genetics
In one analysis, between 15 - 20% of women with cervical cancer had at least one close relative with the disease. Two studies have also reported that in families with cervical cancer there have also been higher rates of other HPV-related and smoking-associated cancers. Inherited factors in such cases most likely cause changes in the immune system that make such people more susceptible to HPV or other viruses.
Use of Oral Contraceptives
Several studies, including a major analysis, have reported a strong association between cervical cancer and long-term use of oral contraception (OC). Women who have taken OCs for more than 10 years have a much higher risk of HPV infection (up to four times higher) than those who do not use OCs. (Women taking OCs for less than 5 years have no significantly higher risk.) The reasons for this risk from OC use are not entirely clear. Women who use OCs may be less likely to use a diaphragm, condoms, or other methods that offer some protection against sexual transmitted diseases, including HPV. Some experts also suggest that the hormones in OCs might facilitate entry of the HPV virus in the genetic material of cervical cells.
Having Many Children
Studies indicate that having many children increases the risk for developing cervical cancer, particularly in women with HPV.
Smoking
Several studies have associated smoking with a higher risk for precancerous changes (dysplasia) in the cervix and for progression to invasive cervical cancer. Secondhand smoke is also linked to increased risk for cervical cancer tumors. It is not clear if this association is due to cigarette smoke’s direct cancer-causing effects or general damage to the immune system. Cigarette smokers are also deficient in folate, a B vitamin. Folate deficiency may play a role in the development of dysplasia.
Exposure to Chemicals
Diethylstilbestrol (DES).
Diethylstilbestrol (DES), an estrogen compound, was used by pregnant women in the 1940s and 1950s. The daughters of these women face a higher risk for cervical cancer, genital tract abnormalities, and miscarriage.
Environmental Chemicals.
One study has reported an increase in cervical cancer mortality in women whose jobs exposed them to harmful chemicals. Such women worked in manufacturing, personal services, farm work, and as nursing aides. More research is needed.
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Review Date: 9/1/2006
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Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.
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