What is Cervical Cancer?

This is the first article in the Understanding Cervical Cancer Guide. This guide was developed by the HealthTree Education Team and was last updated and reviewed on June 16, 2026

Cancer begins when cells in the body start to grow out of control. Cervical cancer starts in the cells that line the cervix, which is the lower part of the uterus that connects to the vagina. The cervix has two main parts covered by two different types of cells, and most cervical cancers start at the place where these two cell types meet.

When you have cervical cancer, cells in the cervix do not follow the normal cell cycle. Healthy cells grow, copy themselves, and then die. Cancer cells change, grow faster than normal, and do not die the way they should.

What is the cervix?

The cervix is the lower, narrow end of the uterus. It forms a canal between the uterus and the vagina. The cervix plays an important role in the female reproductive system.

The cervix has two parts:

• The endocervix is the inner part of the cervix, the canal that runs from the uterus down toward the vagina. It is lined with glandular cells, which are column-shaped cells that make mucus.
• The ectocervix, also called the exocervix, is the outer part of the cervix that a doctor can see during a pelvic exam. It is lined with squamous cells, which are thin and flat.

The area where these two types of cells meet is called the transformation zone. Most cervical cancers start here, because cells in this area can be more easily affected by HPV and can change into abnormal cells over time.

How cervical cancer starts

Almost all cases of cervical cancer are caused by infection with high-risk types of HPV. HPV is a group of more than 200 related viruses. Some types of HPV cause common warts on the hands and feet. Other types are spread through sexual contact and can infect the cervix. High-risk types of HPV, especially HPV-16 and HPV-18, can cause changes in the cells of the cervix that may eventually lead to cancer.

HPV infection is very common. Most people who are sexually active will be infected with HPV at some point in their lives. In most cases, the body's immune system clears the infection on its own within two years, and the person never knows they had it. In some people, the infection does not go away. When high-risk HPV stays in the cervical cells for many years, it can cause the cells to change. These abnormal cells are called cervical dysplasia or a precancerous condition. If these cell changes are not found and treated, they can eventually become cervical cancer, though this process usually takes 10 to 15 years.

How does cervical cancer affect the body?

As cervical cancer grows, it can affect many parts of the body:

How cervical cancer affects the cervix and nearby organs:

Cervical cancer can grow into the cervix itself and spread into the tissues next to the uterus. It can also spread to the vagina, the bladder, and the rectum. These changes can cause symptoms such as unusual vaginal bleeding, pelvic pain, and problems with urination.

How cervical cancer affects the lymph nodes:

Cervical cancer can spread to lymph nodes in the pelvis and around the large blood vessels in the abdomen. When cancer spreads to lymph nodes, it can be harder to treat. Knowing whether lymph nodes are involved is an important part of staging the cancer.

How cervical cancer affects other organs:

When cancer spreads to other parts of the body, it has metastasized. Cervical cancer most often spreads first to nearby tissues, lymph nodes, the vagina, the bladder, and the rectum. When it spreads further, it may travel to the lungs, liver, and bones. This spread can affect how those organs work and may cause additional symptoms.

Learn more about the signs and symptoms of cervical cancer.

Types of cervical cancer

Cervical cancers are classified by the type of cell in which they begin:

• Squamous cell carcinoma. This is the most common type, making up about 70 to 80 percent of cervical cancers. It begins in the thin, flat squamous cells on the outer surface of the cervix. Most squamous cell carcinomas of the cervix are caused by HPV.
• Adenocarcinoma. This type makes up about 20 to 25 percent of cervical cancers. It begins in the glandular cells that line the inner canal of the cervix. HPV types 18 and 16 are the most common causes. Adenocarcinomas can be harder to detect with a Pap test because they develop higher up in the cervical canal.
• Adenosquamous carcinoma. A less common type that has features of both squamous cell carcinoma and adenocarcinoma.
• Other rare types. A small number of cervical cancers are rare types including small cell neuroendocrine carcinoma, glassy cell carcinoma, and others. Some of these types behave more aggressively and are treated differently.

Related conditions

Certain conditions are closely related to cervical cancer and are important to understand:

• Cervical dysplasia. Abnormal cell changes in the cervix that are not yet cancer. Doctors grade these changes from mild to severe. Severe dysplasia is sometimes called carcinoma in situ, which means the abnormal cells are only on the surface of the cervix and have not grown into deeper tissue. Severe dysplasia is treated to prevent it from becoming invasive cancer.
• Cervical intraepithelial neoplasia. Often abbreviated CIN, this is another term used to describe abnormal cell changes in the cervix. CIN is graded on a scale of one to three, with CIN 3 being the most severe and closest to becoming cancer.
• HPV infection. Most cervical cancers are caused by ongoing infection with high-risk HPV. Regular screening and the HPV vaccine are the best ways to prevent HPV from leading to cancer.