The cervix is the lower third portion of the uterus (womb). It serves as a neck to connect the uterus to the vagina. The opening of the cervix, called the os, remains small and narrow, except during childbirth when it widens to allow a baby to pass from the uterus into the vagina.
Cervical cancer develops in the thin layer of cells called the epithelium, which cover the cervix. Cells found in this tissue have different shapes:
- Squamous cells (flat and scaly). Most cervical cancer arises from changes in the squamous cells of the epithelium (squamous cell carcinoma).
- Columnar cells (column-like). These cells line the cervical glands. Cancers found here are known as adenocarcinomas.
- Mixed carcinomas are cells that combine features of squamous cells and adenocarcinomas.
Cervical cancer usually begins slowly with precancerous abnormalities, and even if cancer develops, it generally progresses very gradually. Cervical cancer is the most preventable type of cancer and is very treatable in its early stages. Regular Pap tests and human papillomavirus (HPV) screening can help detect this disease early.
Precancerous Changes in the Cervix
Dysplasia is a term that refers to a precancerous condition. It may become cancerous, but not always. In the case of cervical cancer, dysplasia indicates that the layer of cells that covers the cervix (squamous epithelial cells) are abnormal in size and shape and are beginning to grow. However, the cells are still confined to the surface (epithelial layer)
Review Date: 10/21/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.