Types of cervical cancer

The type of cervical cancer a woman may develop depends on which cells of the cervix — the lower, narrow portion of the uterus that joins with the vaginal canal — are affected. There are two types of cells, known as squamous cells and glandular cells, that may develop into squamous cell carcinoma (cancer of the squamous cells) or adenocarcinoma (cancer of the glandular cells).

Squamous cell carcinoma can be thought of as similar to skin cancer because it begins on the surface of the extocervix,^1,2 a part of the cervix that is closer to the opening of the vaginal canal. Adenocarcinoma begins further inside the uterus, in the mucus-producing gland cells of the endocervix.²

Squamous cell carcinoma

Squamous cells are flat cells on the outer surface of the cervix. They are like the cells you find on the outer layer of your skin. When these cells start to grow abnormally, it is the beginning of squamous cell cancer, or carcinoma. This is the most common form of cervical cancer. The good news is that this type of cancer is generally slow growing. Squamous cell cancer can take three to five years to fully develop. That's why routine pap testing is a good idea to catch changes before they become cancerous.

Adenocarcinoma

The passageway leading from the cervix into the uterus is lined with gland cells that produce mucus; abnormal growth of these cells can lead to adenocarcinoma. The number of women developing adenocarcinoma is on the rise. Reasons for this increase are unclear; it may have to do with the difficulty of finding abnormal cells that are further inside the uterus than squamous cells. The rise of adenocarcinoma serves as a reminder that regular pap testing is an important component of your long-term cervical health.

More about the rise of adenocarcinoma

How does cervical cancer progress?

Cervical cancer usually takes several years to develop, as cells change from "normal" to "precancerous" (dysplastic). Precancerous cells are abnormal cells on the inner surface of the uterus; they have not broken through the lining of the uterus to become invasive. With regular exams, a pap test may detect precancerous changes, which can be treated before cancer develops.³

Precancerous cells are abnormal, but they affect only the surface of the cervical tissue. Over time, precancerous cervical cells can invade deeper into the cervix and grow out of control. They can spread into the tissue near the cervix, or travel to other parts of the body through the blood or lymph fluid. It is more difficult to treat cervical cancer once it spreads to other tissue.³

Cellular changes leading to cancer

What are the symptoms of cervical cancer?

Generally, precancerous changes and early cervical cancer won't necessarily result in clear symptoms. If symptoms do occur, they may include abnormal bleeding, such as:³

• Bleeding between monthly periods
• Bleeding after sex, after douching, or after a pelvic exam

Symptoms may also include:³

• Pelvic pain not related to your menstrual cycle
• Heavy or unusual discharge that may be watery, thick, and possibly have a foul odor
• Increased urinary frequency
• Pain during urination

Be sure to speak to your doctor if you have any of these symptoms.

Who gets cervical cancer?

Most cervical cancer cases are diagnosed between the ages of 35 and 55 years old. However, younger women who are sexually active and older women are also at risk. For this reason, the American Cancer Society recommends:⁴

• Regular pap tests for all women beginning 3 years after first having sex or no later than age 21 and continuing until at least age 70
• Pap tests should be performed every 2 years and should use a liquid-based test

Most cases of advanced cervical cancer are diagnosed in women who have not been getting routine pap tests.³

The role of HPV

While there are many possible risk factors for cervical cancer, HPV (human papillomavirus) is linked to 99.7% of all squamous cell carcinomas and a large portion of adenocarcinomas.

Next: the role of HPV in cervical cancer