Each year, about 15,000 women in the United States learn that they have cancer of the cervix. Cervical cancer is one of the most common cancers of women's reproductive organs. Most cases of cervical cancer are caused by infection with human papillomavirus (HPV).
Before cancer of the cervix appears, the cells of the cervix go through precancerous changes known as dysplasia, in which abnormal cells begin to appear in the cervical tissue; it is these precancerous changes that the annual Pap test is meant to test for. For some women, these changes may go away without any treatment. More often, they need to be treated to keep them from changing into cancer.
Because so many women do have Pap tests annually, deaths from cervical cancer have decreased greatly and are now rare in the United States; however, deaths still occur. Chances of successfully treating cancer are highest when detected early.
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The cervix is part of the female reproductive system. It is the narrow lower end of the uterus, the hollow, pear-shaped organ where a fetus grows. It is about 1 inch around and connects the vagina (birth canal) to the uterus. During a woman's menstrual period, blood flows from the uterus through the cervix to the vagina.
The cervix also produces mucus that helps sperm move from the vagina into the uterus. Sperm travels through the cervix to fertilize a woman's egg during conception.
During pregnancy, the cervix is tightly closed to help keep the baby inside the uterus. During childbirth, the cervix opens or dilates to allow the baby to pass through the vagina.
A sexually transmitted virus called the human papillomavirus (HPV) causes almost all cases of cervical cancer. HPV usually goes away by itself, and most people with HPV never even know they have it. But sometimes an HPV infection can cause larger problems.
HPV can be categorized into two groups: low risk and high risk. Some high-risk types of HPV may stimulate the growth of precancerous cells in the cervix. If these abnormal cells are not found and treated, they may become cancerous. Two of the high-risk HPV strains are HPV 16 and 18. Two of the low-risk HPV strains are 6 and 11. These are the four strains the HPV vaccine Gardasil protects against. Strains 16 and 18 account for about 70 percent of all cervical cancers and a smaller percentage of vaginal and vulval cancers. Studies are being conducted to develop vaccines to prevent the remaining 30 percent of cervical cancers. Some low-risk HPV strains such as strains 6 and 11 can cause genital warts but do not cause cervical cancer. These low-risk strains account for about 90 percent of genital warts.
Women with certain risk factors may be more likely to develop cervical cancer. These factors include:
- Infection with human papillomavirus (HPV): Some types of HPV can cause changes to cells in the cervix. The changes may lead to genital warts, precancerous growths, or cancer.
- Age: The risk of cervical cancer increases with age and most often is diagnosed in women over the age of 40. However, younger women are often diagnosed with precancerous lesions that require treatment to prevent cancer.
- Smoking: Cigarette smoke contains chemicals that damage the body's cells. Smoking increases the risk of precancerous changes in the cervix, especially in women with HPV.
- Sex at an early age: Women who have had sex at an early age have a higher risk of cervical cancer. Researchers are not sure why, but they think HPV may more easily infect a young woman's cervix.
- Number of sexual partners: Women who have had fewer sexual partners have a lower risk of cervical cancer. This is because the more sexual partners a woman has, the greater chance she has of getting HPV.
- Sexually transmitted diseases (STDs): Women who have an STD besides HPV have a higher risk of cervical cancer because the chance of acquiring HPV is also greater.
- Weakened immune system: Women who are HIV positive or take drugs that suppress the immune system, such as women who have undergone organ transplant or take steroids for other reasons, have a higher than average risk of developing cervical cancer.
- Lack of regular Pap tests: Cervical cancer is more common among women who do not have regular Pap tests. The Pap test helps doctors find precancerous cells.In most cases, cervical cancer is treatable or preventable if precancerous changes are caught at an early stage.
There are two main types of cancer of the cervix; each one develops from different tissue types. The most common (about 80 percent to 90 percent) are squamous cell carcinomas. The other 10 percent to 20 percent are adenocarcinomas. Squamous cell carcinoma develops in the lining of the cervix, while adenocarcinoma develops in gland cells that produce cervical mucus. There is some controversy over whether patients with adenocarcinoma of the cervix have a worse prognosis than those with the more common squamous cell carcinoma. Some types of adenocarcinoma are aggressive and are associated with a poor prognosis. The most important factor of prognosis is the stage of the cancer, which will determine the treatment options and outcomes. Treatment options are the same regardless if a cervical cancer is squamous or adenocarcinoma.
Last reviewed on 10/13/09
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