Cervical cancer
Description
An in-depth report on the causes, diagnosis, treatment, and prevention of cervical cancer.
Alternative Names
Dysplasia; Human papillomas virus; Pap smear
Introduction
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.
The uterus is a hollow muscular organ located in the female pelvis between the bladder and rectum. The ovaries produce the eggs that travel through the fallopian tubes. Once the egg has left the ovary it can be fertilized and implant itself in the lining of the uterus. The main function of the uterus is to nourish the developing fetus prior to birth.
Cervical cancer develops in the thin layer of cells called the
epithelium
, which cover the cervix. Cells found in the 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 and cancers here are known as
adenocarcinomas.
-
In rare cases, cancer can occur in cells that form the supportive tissue around the cervix (the
stroma
).
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 papilloma virus (HPV) screening can help detect this disease early.
Precancerous Changes in the Cervix
Dysplasia.
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.
Cervical Intraepithelial Neoplasia (CIN).
Dysplastic changes seen on a Pap smear may indicate the presence of
cervical intraepithelial neoplasia
(
CIN
). This means precancerous changes are found
within
the lining of the cervix. The changes are categorized according to severity: CIN I, CIN II, and CIN III (which includes
carcinoma in situ
).
-
With CIN I, there are mild abnormalities that rarely develop into cervical cancer. This condition may progress if untreated but often goes away without treatment.
-
In CIN II, the lesions often appear more aggressive under the microscope and may turn into cancer unless treated.
-
CIN III is the most aggressive form of dysplasia. If not removed, there is a high chance that it will turn into invasive cancer. CIN III includes carcinoma in situ (CIS). CIS is an early stage of
non-invasive
cancer -- the cells are confined within the tissue where they grew and have not yet invaded surrounding tissue. CIS is included in the CIN III category of precursor lesions. However since CIS can progress to
invasive
cancer, this condition should be treated as soon as possible.
Invasive Cervical Cancer
The cells of the epithelium rest on a very thin layer called the
basement membrane
. Invasive cervical cancer occurs when cancer cells in the epithelium cross this membrane and invade the
stroma
, the underlying supportive tissue of the cervix.
In later stages, the original cancer may spread to areas surrounding the uterus and cervix or near organs such as the bladder or rectum. It may also spread to distant sites in the body by way of the bloodstream or the lymph nodes.
-
Review Date: 9/1/2006
-
Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.
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