Cancer

Cervical cancer

The female reproductive system: the cervix

Located in the lower part of a woman's abdomen between the bladder and the rectum, the uterus is a pear-shaped organ. The cervix is the lower, narrower part of the uterus. It forms a canal leading through the vagina and out of the body. The part of the cervix closest to the body of the uterus is called the endocervix (endo = inside). The part next to the vagina is called the ectocervix (ecto = outside). Most cervical cancers begin where the endocervix and ectocervix meet.

What is cancer?

The body's basic unit—the cell—has a life cycle during which it grows, divides, and dies. Cells divide to produce more cells only when additional cells are needed by the body. This orderly life cycle is what keeps the body healthy. During childhood and adolescence, normal cells divide more rapidly until a person reaches adulthood. After that, cells in most parts of the body divide only to replace old or dying cells and to repair injured organs or tissues. However, cancer occurs when abnormal cells divide without control or order. Rather than dying, cancer cells outlive normal cells and continue to produce new, abnormal cells.

Cancer cells develop as a result of damage to deoxyribonucleic acid, or DNA. Present in every cell of the body, DNA directs the activities of the cell. In most cases, when DNA becomes damaged, the body is able to repair it. In cancer cells, however, damaged DNA is not repaired. The cell takes on an abnormal life cycle and continues to grow and divide in an out-of-control fashion. Cells continue to divide when new cells are not needed, resulting in a mass of extra tissue. Such masses—known as tumors—may be benign or malignant.

Benign tumors are not cancer. Non life-threatening, these can be removed and generally, they do not recur. Cells from benign growths do not metastasize (spread) to other parts of the body. Polyps, cysts, and genital warts are all examples of benign growths affecting the cervix.

Malignant tumors, on the other hand, are cancerous. Such growths can invade and damage nearby tissues and organs through a process called metastasis. Cancer cells can also break away from a malignant tumor and enter the body's lymphatic system or bloodstream, replacing normal tissue. This is how cervical cancer can spread (metastasize) to other parts of the body such as the lymph nodes, rectum, bladder, lungs, and bones of the spine.

What is cervical cancer?

Cancer of the cervix—also called cervical cancer—is named for the part of the body it affects and also for the type of cell in which it begins. Thus, cervical cancer, which begins in the lining of the cervix, can be of two types: squamous cell carcinoma and adenocarcinoma. These cancers, as well as cervical precancers, are classified according to how they look under a microscope.

Squamous cell carcinomas

Approximately 80 to 90 percent of cervical cancers are squamous cell carcinomas, composed of cells resembling the flat, thin squamous cells covering the surface of the endocervix. Squamous cell carcinomas generally begin where the ectocervix joins the endocervix.¹

Adenocarcinomas

The remaining 10 to 20 percent of cervical cancers are adenocarcinomas and are more common in women born in the last 20 to 30 years. Cervical adenocarcinoma develops from the mucus-producing gland cells of the endocervix.²

In some instances, cervical cancers have features of both squamous cell carcinomas and adenocarcinomas. Such cancers are called adenosquamous carcinomas or mixed carcinomas.

How does cervical cancer develop?

Cervical cancer does not develop suddenly or spontaneously. Over time, normal cervical cells gradually develop precancerous changes that eventually develop into cancer. Although this process usually takes several years, it can sometimes happen in less than a year. There are several terms used to describe precancerous changes, including:³

• cervical intraepithelial neoplasia (CIN)
• central intraepithelial lesion (CIL; which can lead to squamous intraepithelial lesion (SIL)/li>
• dysplasia

Cervical intraepithelial neoplasia (CIN)

Cervical intraepithelial neoplasia is classified according to the degree of cell abnormality. Low-grade cervical intraepithelial neoplasia indicates a minimal change in the cells whereas high-grade cervical intraepithelial neoplasia indicates a greater degree of abnormality.⁴

Squamous intraepithelial lesion (SIL)

Cervical intraepithelial neoplasia can progress to squamous intraepithelial lesion (SIL), a condition that precedes cervical cancer, or to carcinoma in situ. Like cervical intraepithelial neoplasia, squamous intraepithelial lesion can also be classified as low grade or high grade.

Low-grade SIL refers to early changes in the size, shape, and number of cells that form the surface of the cervix. While some low-grade lesions may go away on their own, others may grow larger or become more abnormal, forming a high-grade lesion. Precancerous low-grade lesions can also be called mild dysplasia (see below) or cervical intraepithelial neoplasia 1 (CIN 1). Although these types of early changes in the cervix most commonly occur in women between 25 and 35 years of age, they can appear in other age groups as well.⁵

High-grade SIL refers to the presence of a large number of precancerous cells. As in low-grade SIL, these precancerous changes involve only cells on the surface of the cervix. It will likely take many months—and perhaps year—for these cells to become cancerous and to invade deeper layers of the cervix. High-grade lesions can also be called moderate or severe dysplasia, CIN 2 or 3, or carcinoma in situ. While these conditions generally affect women between the ages of 30 and 40, they can occur at other ages as well.⁶

Dysplasia

Dysplasia describes a precancerous condition which can develop into cervical cancer. In most women, particularly young women, dysplasia, depending on its severity, can go away without treatment. However, dysplasia often progresses to actual cancer called carcinoma in situ (CIS) if it has not spread or microinvasive if it has spread only a few millimeters into surrounding tissue and not into lymph channels or blood vessels. Although it can take several years for dysplasia to develop into carcinoma in situ or microinvasive cancer, once it has occurred, this cancer can spread quickly into nearby tissues or other organs (such as the bladder, rectum, intestines, liver, or lungs).⁷

What causes cervical cancer? What are the risk factors?

A risk factor is anything that increases your risk of developing a particular disease. There are several risk factors that can increase your chance of developing cervical cancer. Women without any risk factors rarely develop cervical cancer. Although risk factors do increase the risk of developing cervical cancer, many women with these risks don't develop the disease. When a woman does develop cervical cancer, it's difficult to say with absolute certainty that one risk factor or another was the cause. Understanding the risk factors is important and it ought to convince women with these factors to get a Pap test. A Pap test is vital in the early detection of cervical cancer.

Human papilloma virus (HPV)

HPV is a sexually transmitted infection; see HPV for more information on the risk factors for HPV, symptoms, and prevention.

The most important risk factor for cervical cancer is infection by the human papilloma virus (HPV), a group of more than 100 types of viruses that can cause warts (or papillomas) which themselves are non-cancerous tumors. Certain types of human papilloma viruses, called high-risk HPVs, however, can cause cervical cancer. These include HPV 16, HPV 18, HPV 31, HPV 33, and HPV 45, as well as some others. Nearly 50 percent of all cervical cancers are caused by HPV 16 and HPV 18.⁸

Most women with the cancer-causing types of HPV don't develop cervical cancer. Because the woman's immune system has been successful in fighting the virus, the HPV infection usually disappears without any treatment.

HPV infection causes abnormal changes in the cells of the cervix; these abnormal cells are found with a Pap test or biopsy. New tests can now directly identify HPV by finding HPV DNA within cells of the cervix. Many doctors are now testing for HPV if the results of the Pap test reveal the presence of atypical squamous cells (ASC). If a high-risk type of HPV is found, a colposcopy is performed and further treatment is considered.

Although it is necessary to have had HPV for cervical cancer to develop, most women with HPV do not develop cervical cancer. It's believed that other factors must come into play in order for cancer to develop.

Smoking

Women who smoke are believed to be about twice as likely as non-smokers to develop cervical cancer. Smoking exposes the body to carcinogens (cancer-causing agents) that affect more than just the lungs. Carcinogens are absorbed by the lungs and carried in the bloodstream throughout the body. By-products of tobacco have been found in the cervical mucus of women who smoke. Researchers believe these substances damage the DNA of cervical cells and may contribute to the development of cervical cancer.

Human immunodeficiency virus (HIV)

Human immunodeficiency virus (HIV) is the virus that leads to acquired immunodeficiency syndrome (AIDS). Because HIV attacks the body's immune system, it makes an infected woman more susceptible to opportunistic infections, including HPV. HPV, as we've seen, increases the risk of cervical cancer. In women with HIV, cervical precancers may progress to invasive cancers more quickly than in women without HIV.

Chlamydia infection

Chlamydia, a sexually transmitted infection caused by a relatively common kind of bacteria, affects the female reproductive system and may or may not cause symptoms. Many women do not know they are infected with chlamydia unless samples taken at the time of their Pap test are analyzed for this type of bacteria. Recent studies suggest that women whose blood tests show past or current chlamydia infection are at greater risk for cervical cancer than women with a negative blood test. Until more is known for sure, there is already good reason to avoid chlamydia infection and to undergo treatment with antibiotics. Long-term chlamydia infection is well known as a cause of pelvic inflammatory disease (PID) which may lead to infertility.

Diet

There is a direct link between diet and cervical cancer: women whose diets are low in fruits and vegetables—and women who are overweight—may be at increased risk of developing cervical cancer.

Oral contraceptives (birth control pills)

There is also evidence to suggest that long-term use of oral contraceptives (birth control pills) increases the risk of cervical cancer. Research suggests that there is a link between the use of oral contraceptives for 5 years or more and an increase in the risk of cervical cancer. In one study, risk was four times greater in women who had used oral contraceptives for 10 years or more.⁹

Multiple pregnancies

Women who have had many full-term pregnancies have an increased risk of developing cervical cancer.

Diethylstilbestrol (DES)

A hormonal drug prescribed between 1940 and 1971 to women thought to be at increased risk for miscarriages, DES has been linked to increased risk of cervical cancer. Of every 1,000 women whose mother took DES when pregnant with them, about 1 develops clear-cell adenocarcinoma of the vagina or cervix. Approximately 99.9 percent of "DES daughters" do not develop cervical cancer.¹⁰

Family history of cervical cancer

Women whose mother or sister(s) have had cervical cancer are more likely to develop the disease themselves. Researchers believe this is because an inherited condition makes these women more susceptible than others to HPV infection.

What are the signs and symptoms of cervical cancer?

Unfortunately, precancers and early cancers usually show no signs or symptoms. Symptoms usually develop when the cancer has become invasive and has spread to nearby tissue. When this occurs, the most common symptom is abnormal vaginal bleeding or an unusual vaginal discharge (separate from the normal monthly menstrual period). Menstrual bleeding may last longer and be heavier than usual. Other symptoms may include bleeding after menopause or increased vaginal discharge.

Other common symptoms include bleeding during intercourse, douching or after a pelvic exam. Pain during intercourse may also be a sign of cervical cancer.

These symptoms, however, may be caused by other conditions and not necessarily by cervical cancer. An infection can cause pain and bleeding. If you have any of the symptoms listed above, be sure to see a doctor right away. Ignoring symptoms can allow the cancer to progress to a more advanced stage, decreasing your chance for effective treatment.

Rather than wait for symptoms to appear, ensure you have regular Pap tests and pelvic examinations.

Your family doctor can usually treat precancers. However, if your biopsy results confirm a diagnosis of cervical cancer, you may need to consult with an gynecologic oncologist, a doctor who specializes in women's reproductive cancers.

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1. What is Cervical Cancer? American Cancer Society. (2004)
2. What is Cervical Cancer? American Cancer Society. (2004)
3. What is Cervical Cancer? American Cancer Society. (2004)
4. Cervical Cancer. Healthcommunities.com (1998–2004)
5. Precancerous Conditions and Cancer of the Cervix. National Cancer Institute.
6. Precancerous Conditions and Cancer of the Cervix. National Cancer Institute.
7. Cervical cancer. U.S. National Library of Medicine. (2004)
8. What are the Risk Factors for Cervical Cancer? American Cancer Society. (2004)
9. What are the Risk Factors for Cervical Cancer? American Cancer Society. (2004)
10. What are the Risk Factors for Cervical Cancer? American Cancer Society. (2004)

Also be sure to read…

Cervical cancer
How can I avoid or prevent cervical cancer?
Diagnostic tests for women with abnormal cervical cytology results
Treating cervical cancer
Pap test
Chlamydia
Human papilloma virus (HPV)