Cervical Cancer

Cervical Cancer Information Image

Cervical cancer is the second most common cancer in women worldwide after breast cancer, and in developing countries, the leading cause of death by cancer.

According to US cervical cancer statistics, the disease is the third most common gynecological cancer among American women, with close to 12,000 new cases diagnosed annually. It used to be one of the leading cancer killers in the US, but once the routine use of Pap smears was implemented, cervical cancer deaths rapidly declined and continue to decline by about two percent per year.

Invasive Cervical Cancer Statistics

When abnormal cells spread beyond the lining of the cervix into surrounding tissues or organs (metastasis), the cancer has become invasive. Invasive cervical cancer is divided into three types:

  • Squamous cell carcinoma is the most common and makes up about eighty to ninety percent of all cervical cancers.
  • Adenocarcinoma makes up ten to twenty percent of cervical cancers.
  • Adenosquamous carcinomas (or mixed carcinomas) are a combination of both squamous cell carcinomas and adenocarcinomas.

Invasive cervical cancers most often appear in women over forty who have not been screened with regular Pap smear tests.

Information on Cervical Cancer Types

Most cervical cancers begin with the formation of abnormal, or pre-cancerous, cells and take many years to develop. Regular screening with Pap smears can result in early detection of cervical cancer at a stage when it is highly treatable.

The cervix is the narrowest part of the uterus and acts as the doorway between the uterus and the vagina. During a Pap smear, a gynecologist scrapes off some of the cells lining the cervix and “smears” them onto a slide for microscopic evaluation.

Cervical cancer occurs when abnormal cells form in the lining of the cervix, but not all abnormal cells are cancerous. Pre-cancerous cells may go away without any treatment or they can become cervical cancer over time.

Pre-Cancerous Conditions

Pre-cancerous conditions are named for the appearance of their cells as they look under a microscope and for their location. Squamous intraepithelial lesions, or SILs, are named for their flat, thin shape. Squamous cells line the surface of many tissues in the body (epithelial tissues), including the cervix. Cervical SILs occur within the epithelial layer of the cervix. Infection with human papillomavirus (HPV) is a high risk factor for SILs and cervical cancer.

Pre-cancerous conditions are further classified according to the number and shapes of abnormal cells. Low-grade SIL, also termed cervical intraepithelial neoplasia 1 (CIN 1), marks the beginning of changes in the size, shape and number of abnormal cells formed on the surface of the cervix. Low-grade SILs are most often found in women between the ages of 25 and 30. As the number of pre-cancerous cells increases, the lesions become high-grade SILs, also known as CIN 2, CIN 3, or carcinoma in situ. High-grade SILs are most often found in women between the ages of 30 and 40.

Definition: “Dysplasia” is a term often used to describe the presence of abnormal cells seen in a lesion that is not cancerous but could become cancerous. Mild dysplasia would have a low number of abnormal cells, while severe dysplasia would have a high number of abnormal cells.


American Cancer Society. (updated 2003). Detailed guide: Cervical cancer. Retrieved August 14, 2003, from www.cancer.org/docroot/CRI/CRI_2_3x.asp?dt 8.

Fauci, A., Braunwald, E., Isselbacher, K., Wilson, J., Martin, J., Kasper, D., Hauser, S., Longo, D. (ed). Harrison’s Principles of Internal Medicine, 14th Edition. McGraw-Hill, New York, 1998.

Memorial Sloan-Kettering Cancer Center. (2003). Cervical cancer. Retrieved August 26, 2003, from www.mskcc.org/mskcc/html/300.cfm.

National Cancer Institute. (updated 2002). Cervical cancer homepage. Retrieved August 22, 2003, from www.cancer.gov/cancerinfo/types/cervical.