The American Cancer Society estimates that nearly 11,150 women will be diagnosed with cervical cancer in 2007. At one time, cervical cancer was considered one of the most deadly cancers for women. Thanks to effective screening, which can detect cervical precancers and cancers early, most cases of cervical cancer can be cured.
With the advent of widespread screening by a vaginal smear test developed by George Papanicolaou in the 1950s (commonly known as the "Pap smear"), the number of deaths from cervical cancer has fallen dramatically -- from more than 35,000 per year to less than 4,000 per year today.
The most significant risk factor for cervical cancer is infection with the human papillomavirus (HPV), which can be transmitted during sex. For more information about ways to prevent HPV and cervical cancer, see the Risk Factors & Prevention section of this overview.
A Slow-Growing, Treatable Cancer
Cervical cancer is cancer of the cervix -- the lower part of the uterus that extends into the upper end of the vagina. The majority of cervical cancers begin where the inner part of the cervix closest to the uterus (the endocervix) meets the outer part of the cervix closest to the vagina (the ectocervix). This area is called the "transformation zone."
Cervical cancer usually grows slowly over many years. Before true cancer cells develop, the tissues of the cervix undergo changes at the cellular level -- called dysplasia, or precancers -- that a pathologist can detect in a Pap smear. These changes range from mild dysplasia or cervical intraepithelial neoplasia (CIN1) to moderate (CIN2) to severe (CIN3), which is also known as carcinoma in situ (an early type of cancer that has not spread to nearby tissues and only involves cells in the tissue where it originated).
If left untreated, these precancers have the propensity to spread deeper into the tissue and become cancerous. Once they spread beyond the borders of the cervix, they can invade more deeply into tissues in the vagina, rectum, or bladder, and ultimately metastasize to other parts of the body.
Types of Cervical Cancer
There are two main types of cervical cancer:
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Squamous Cell Carcinoma
The majority of cervical cancers -- 80 to 90 percent -- are squamous cell carcinomas. These cancers originate in the squamous cells, which are the thin, flat cells that cover the surface of the ectocervix. The majority of cervical cancers begin where the endocervix and the ectocervix meet.
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Adenocarcinoma
Ten to 20 percent of cervical cancers are adenocarcinomas, which are those cancers that begin in the gland-like cells that line the endocervix.
Cancers that have features of both cell types are known as mixed, or adenosquamous, carcinomas.
