The vagina is a 3 to 4 inch (7 1/2 to 10 cm) tube. Its upper part ends at the cervix, the lower part of the uterus (womb). The lower end opens to the outside onto the vulva, the external genitals. The vagina is sometimes called the birth canal. A thin layer called the epithelium lines the walls of the vagina. The epithelium is formed by squamous epithelial cells.

The part of the vaginal wall underneath the epithelium contains connective tissue, muscle tissue, lymph vessels, and nerves. The vagina is usually in a collapsed state with its walls touching each other. The vaginal walls have many folds that help the vagina to open and expand during sexual intercourse or birth of a baby. Glands in its wall secrete mucus to keep the vaginal lining moist.

There are several types of vaginal cancer. About 85% to 90% of vaginal cancers are squamous cell carcinomas that begin in the epithelial lining of the vagina. They tend to occur in the upper area of the vagina near the cervix. Vaginal squamous cell carcinomas do not appear suddenly; they develop over a period of many years from precancerous changes called vaginal intraepithelial neoplasia (often abbreviated as VAIN).

About 5% to 10% of vaginal cancers are adenocarcinomas. The usual type of vaginal adenocarcinoma typically develops in women older than 50. One special type, called clear cell adenocarcinoma, occurs more often in young women who were exposed to diethylstilbestrol (DES) in utero (when they were in their mother's womb). In the past some pregnant women were given DES to prevent miscarriage. The drug became available during the late 1940s and was banned in the USA in 1971. (See the section on risk factors for more information on DES and clear cell carcinoma.)

Malignant melanoma is a cancer that develops from pigment-producing cells called melanocytes. These cancers usually are found on sun-exposed areas of the skin but occasionally form on the vagina or other internal organs. They account for about 2% to 3% of all vaginal cancers. Melanoma tends to affect the lower or outer portion of the vagina. The tumors vary greatly in size, color, and growth pattern.

About 2% to 3% of vaginal cancers are sarcomas. These cancers form deep in the wall of the vagina, not on its surface epithelium. There are several types of vaginal sarcomas. The most common, leiomyosarcoma, typically affects women older than 50. Leiomyosarcomas resemble the involuntary muscle cells of the vaginal wall. Rhabdomyosarcoma is a childhood cancer, usually found before the age of 3. Its cells resemble voluntary muscle cells – a tissue not normally found in the vaginal wall.

Cancers of the vagina are much less common than cancers that start in other organs (such as the uterus, rectum, or bladder) and secondarily spread to the vagina. This document refers only to primary vaginal cancers, that is, those starting in the vagina.

Revised: 07/21/2006