Cervical Cancer

What is cervical cancer?
Cervical cancer begins in the cells lining the cervix - the lower part of the uterus (womb). This is sometimes called the cervix. The fetus grows in the body of the uterus (the top). The cervix connects the body of the uterus to the vagina (birth canal). The part of the cervix closest to the body of the uterus is called the endocervix. The next part of the vagina is the ectocervix (or ectocervix). The 2 main types of cells lining the cervix are squamous cell (the ectocervix) and glandular cells (the endocervix). These types of cells 2 are in a place that is called the transformation zone. The exact location of the transformation zone changes as you get older and if you give birth.



Most cervical cancers begin in cells in the transformation zone. These cells do not suddenly change into cancer. In contrast, normal cells of the cervix first precancerous changes that become cancer develop gradually. Doctors use several terms to describe these pre-cancerous changes, including cervical intraepithelial neoplasia (CIN), squamous intraepithelial lesion (SIL), and dysplasia. These changes can be detected by the Pap test and treated to prevent the development of cancer (see "Can you prevent cervical cancer?").

Cervical pre-cancers and cervical cancers are classified by their appearance under the microscope. The main types of cervical cancers are squamous cell carcinoma and adenocarcinoma.

Most (up to 9 in 10) cervical cancers are squamous cell carcinomas. These cancers form cells from the ectocervix and cancer cells are squamous cell characteristics under the microscope. Squamous cell carcinomas most often begin in the transformation zone (where the ectocervix joins the endocervix).

Most other types of cervical cancers are adenocarcinomas. Adenocarcinomas are cancers that develop from gland cells. Cervical adenocarcinoma develops from the cells of mucus-producing glands of the endocervix. Cervical adenocarcinomas seem to have become more common in the last 20-30 years.

Less commonly, cervical cancer have features of both squamous and adenocarcinoma cells. These are called adenosquamous carcinomas or mixed carcinomas.

Although cervical cancers start from cells with pre-cancerous changes (pre-cancers), only some women with precancerous lesions of the cervix will develop cancer. It usually takes several years for cervical pre-cancer to change for cervical cancer, but it can happen in less than a year. For most women, precancerous cells disappear without treatment. However, in some women pre-cancers become true cancers (invasive). Treatment of all cervical pre-cancers can prevent almost all true cancers of the cervix. Precancerous changes and specific types of treatment for pre-cancers are discussed in our document on Prevention of Cervical Cancer and early detection.

Although almost all cervical cancers are squamous cell carcinomas or adenocarcinomas, other types of cancer can also develop in the cervix. These other types such as melanoma, sarcoma, lymphoma, and most commonly occur in other body parts.