Cervical Cancer

What Is Cervical Cancer?

Cervical cancer is a disease caused by the abnormal growth and division of cells that make up the cervix, which is the narrow, lower end of the uterus (womb).

“Cancer” is the name for a group of diseases in which certain cells in the body have changed in appearance and function. Instead of dividing and growing in a controlled and orderly way, these abnormal cells can grow out of control and form a mass or “tumor.”

A tumor is considered benign (not cancerous) if it is limited to a few cell layers and does not invade surrounding tissues or organs. But if the tumor spreads – or has the potential to spread – to surrounding tissues or organs, it is considered malignant, or cancerous.

The cervix is composed of three layers of tissue:

• An outer lining known as the serous membrane (slippery covering)
• A middle, muscular layer
• An inner lining known as the mucous membrane, which is composed of thin, flat, scaly cells called squamous cells. This inner lining has many tiny glands that secrete a clear, lubricating mucous.

Nearly all cervical cancers arise from the cells of the inner lining of the cervix.

Normally, cervical cells grow in an orderly fashion. However, when control of that growth is lost, cells divide too frequently and too fast.

Certain well-defined cellular changes may progress to cervical cancer:

• Mild cervical dysplasia results when irregular cells are limited to the deepest one-third of the surface cell layer (known as the epithelium) that lines the cervix.
• Moderate cervical dysplasia occurs when uncontrolled cell growth continues, and up to two-thirds of the surface cell layer is abnormal.
• If abnormal cell growth progresses to include the full thickness of the surface cell layer, the condition is known as severe cervical dysplasia, or carcinoma in situ, or CIS. Carcinoma in situ does not penetrate surrounding tissues, stays within the confines of the epithelium, and is considered benign.

A tumor is considered malignant (cancerous) if abnormal cells:

• Penetrate the membrane that separates the surface cell layer and the underlying supportive tissue (called the stroma) of the cervix.
• Spread to the surrounding tissues or organs.

There are several types of cervical cancer:

• Squamous cell carcinoma (SCC) is the most common type of cervical cancer, accounting for 85% to 90% of all cases. It develops from the cells that line the inner part of the cervix, called the squamous cells. It usually begins where the part of the cervix that connects with the vagina (called the ectocervix) meets the part of the cervix that opens into the uterus (called the endocervix).
• Adenocarcinoma develops from the column-shaped cells that line the mucous-producing glands of the cervix. In rare instances, adenocarcinoma originates in the supportive tissue around the cervix. Adenocarcinoma accounts for about 10% of all cervical cancers.
• Mixed carcinomas (for example, adenosquamous carcinomas) combine features of both squamous cell carcinoma and adenocarcinoma.