The cervix is the lower part or neck of the uterus and connects the body of the uterus to the vagina. Cervical cancer typically presents as a malignant neoplasm in the tissues of the cervix, which becomes abnormal and grows uncontrollably, producing tumors. In approximately 90% of all cervical cancers, the malignancy originates in the thin, flat, squamous cells on the surface of the ectocervix (part of the cervix that is next to the vagina) and is called squamous cell carcinoma. In 10% of the cervical cancers, the malignancy originates in the mucus-producing cells of the inner or endocervix (near to the body of the uterus) and is called adenocarcinoma. In rare cases, the cervical cancer may have characteristics of both types of malignancy and is called adenosquamous carcinoma or mixed carcinoma.
As cervical cancer develops, the cervical cells may not be cancerous but may undergo precancerous changes to form lesions called dysplasia or squamous intraepithelial lesions (SIL). Moderate to severe dysplasia may be referred to as carcinoma in situ or non-invasive cervical cancer. Eventually, the precancerous cells can become malignant and begin to grow uncontrollably into the deeper layers of the cervix resulting in an invasive cervical cancer.
The incidence of cervical cancer is highest among poor women and among women in developing countries. Since these women are much less likely to receive regular Pap tests, their cervical cancers usually are diagnosed at a much later stage, after the cancer has spread to other parts of the body. The Pap test can identify precancerous and early-invasive stages of cervical cancer. When detected at an early stage, cure rates are nearly 100%.