What is cervical cancer?
Cervical cancer starts in the cells lining the cervix which is the lower part of the uterus. The cervix connects the body of the uterus to the vagina (birth canal). The cervix has 2 parts: the endocervix and the exocervix. The endocervix is the closest to the uterus and the exocervix is closest to the vagina. The 2 main types of cells covering the cervix are squamous cells (on the exocervix) and glandular cells (on the endocervix). These 2 cell types meet at a place called the transformation zone. The exact location of the transformation zone changes as you age and if you give birth.
Most cervical cancers begin in the cells in the transformation zone. These cells do not suddenly change into cancer. Instead, the normal cells of the cervix gradually develop into pre-cancerous cells that can then turn into cancer. These changes can be detected by the Pap test and treated to prevent cancer from developing.
Types of Cervical Cancer
Cervical cancers and cervical pre-cancers are classified by how they look under a microscope. The main types of cervical cancers are squamous cell carcinoma and adenocarcinoma.
About 90% of cervical cancers are squamous cell carcinomas that develop from cells in the exocervix. Squamous cell carcinomas most often begin in the transformation zone.
Most of the other cervical cancers are adenocarcinomas. Cervical adenocarcinoma develops from the mucus-producing gland cells of the endocervix.
On rare instances, cervical cancers have features of both squamous cell carcinomas and adenocarcinomas. These are called adenosquamous carcinomas or mixed carcinomas.
Although cervical cancers start from cells with pre-cancerous changes, only some of the women with pre-cancers of the cervix will develop cancer. It usually takes several years for cervical pre-cancer to change to cervical cancer, but it can happen in less than a year. Treating all cervical pre-cancers can help prevent almost all invasive cervical cancers.
Although almost all cervical cancers are either squamous cell carcinomas or adenocarcinomas, other types of cancer also can develop in the cervix. These other types, such as melanoma, sarcoma, and lymphoma, occur more commonly in other parts of the body.
What are the risk factors for cervical cancer?
Cervical cancer risk factors include:
Human papillomavirus infection HPV:
The most important risk factor for cervical cancer is infection by HPV. HPV is a group of more than 150 related viruses, some of which cause a type of growth called papillomas, also known as warts.
HPV can infect cells on the surface of the skin, and those lining the genitals, anus, mouth and throat, but not the blood or internal organs such as the heart or lungs.
HPV can be spread from one person to another during skin-to-skin contact. One way HPV is spread is through sex, including vaginal, anal, and even oral sex.
Doctors believe that a woman must be infected with HPV in order to develop cervical cancer. Although this can mean infection with any of the high-risk types, about two-thirds of all cervical cancers are caused by HPV-16 and HPV-18.
Infection with HPV is common, and in most people, the body can clear the infection by itself. Sometimes, however, the infection does not go away and becomes chronic. Chronic infection, especially when it is caused by certain high-risk HPV types, can eventually cause certain cancers, such as cervical cancer.
Women who smoke are about twice as likely as non-smokers to get cervical cancer. Tobacco by-products have been found in the cervical mucus of women who smoke. Researchers believe that these substances damage the DNA of cervical cells and may contribute to the development of cervical cancer. Smoking also makes the immune system less effective in fighting HPV infections.
Human immunodeficiency virus (HIV), the virus that causes AIDS, damages the immune system and puts women at higher risk for HPV infections. This might explain why women with AIDS have a higher risk for cervical cancer. The immune system is important in destroying cancer cells and slowing their growth and spread. In women with HIV, a cervical pre-cancer might develop into invasive cancer faster than it normally would. Another group of women at risk of cervical cancer are those taking drugs to suppress their immune response, such as those being treated for an autoimmune disease or those who have had an organ transplant.
Chlamydia is a relatively common kind of bacteria that can infect the reproductive system. It is spread by sexual contact. Some studies have seen a higher risk of cervical cancer in women whose blood test results show evidence of past or current chlamydia infection. Women who are infected with chlamydia often have no symptoms, in fact, they may not know that they are infected at all unless they are tested for chlamydia during a pelvic exam.
A diet low in fruits and vegetables
Women whose diets don’t include enough fruits and vegetables may be at increased risk for cervical cancer.
Overweight women are more likely to develop adenocarcinoma of the cervix.
Long-term use of oral contraceptives (birth control pills)
There is evidence that taking oral contraceptives (OCs) for a long time increases the risk of cancer of the cervix. Research suggests that the risk of cervical cancer goes up the longer a woman takes OCs, but the risk goes back down again after the OCs are stopped.
Having multiple full-term pregnancies
Women who have had 3 or more full-term pregnancies have an increased risk of developing cervical cancer. One theory to why this is true is that these women had unprotected intercourse to get pregnant, so they may have had exposure to HPV. Also, studies have pointed to hormonal changes during pregnancy as possibly making women more susceptible to HPV infection or cancer growth. Another thought is that pregnant women might have weaker immune systems, allowing for HPV infection and cancer growth.
First full-term pregnancy before the age of 17
Women who were younger than 17 years when they had their first full-term pregnancy are almost 2 times more likely to get cervical cancer later in life than women who waited to get pregnant until they were 25 years or older.
Having a family history of cervical cancer
If your mother or sister had cervical cancer, your chances of developing the disease are 2 to 3 times higher than if no one in the family had it. Some researchers suspect that some instances of this familial tendency are caused by an inherited condition that makes some women less able to fight off HPV infection than others. In other instances, women from the same family as a patient already diagnosed could be more likely to have one or more of the other non-genetic risk factors previously described in this section.
Can cervical cancer be found early?
The best way to find cervical cancer early is to have regular screening with a Pap test (which may be combined with a test for human papillomavirus or HPV). As Pap testing became routine in this country during the past half-century, finding pre-cancers of the cervix became far more common than finding invasive cancer.
How is cervical cancer treated?
General treatment information:
The options for treating each patient with cervical cancer depend on the stage of the disease. The stage of cervical cancer describes its size, how far it has grown into the cervix, and how far it has spread.
After establishing the stage of your cervical cancer, your cancer care team will recommend your treatment options. Depending on the type and stage of your cancer, you may need more than one type of treatment.
Doctors on your cancer treatment team may include:
- A gynecologist: a doctor who treats diseases of the female reproductive system
- A gynecologic oncologist: a doctor who specializes in cancers of the female reproductive system
- A radiation oncologist: a doctor who uses radiation to treat cancer
- A medical oncologist: a doctor who uses chemotherapy and other medicines to treat cancer
Many other specialists may be involved in your care as well, including nurse practitioners, nurses, psychologists, social workers, rehabilitation specialists, and other health professionals.
Common types of treatments for cervical cancer include:
- Radiation therapy
- Chemotherapy (chemo)
For the earliest stages of cervical cancer, either surgery or radiation combined with chemo may be used. For later stages, radiation combined with chemo is usually the main treatment. Chemo (by itself) is often used to treat advanced cervical cancer.