Tipos de Cancer   /   Cánceres Ginecológicos

NCI/PDQ^® Patients: Cervical Cancer Treatment (PDQ®)

National Cancer Institute
Ultima Vez Modificado: 18 de septiembre del 2012

TABLE OF CONTENTS

• General Information About Cervical Cancer

• Stages of Cervical Cancer

• Recurrent Cervical Cancer

• Treatment Option Overview

• Treatment Options by Stage
  • Carcinoma in Situ (Stage 0)
  • Stage IA Cervical Cancer
  • Stage IB Cervical Cancer
  • Stage IIA Cervical Cancer
  • Stage IIB Cervical Cancer
  • Stage III Cervical Cancer
  • Stage IVA Cervical Cancer
  • Stage IVB Cervical Cancer

• Treatment Options for Recurrent Cervical Cancer

• To Learn More About Cervical Cancer

• Changes to This Summary (09/18/2012)

• Get More Information From NCI

• About PDQ®

General Information About Cervical Cancer

Cervical cancer is a disease in which malignant (cancer) cells form in the tissues of the cervix.

The cervix is the lower, narrow end of the uterus (the hollow, pear-shaped organ where a fetus grows). The cervix leads from the uterus to the vagina (birth canal).

Cervical cancer usually develops slowly over time. Before cancer appears in the cervix, the cells of the cervix go through changes known as dysplasia, in which cells that are not normal begin to appear in the cervical tissue. Later, cancer cells start to grow and spread more deeply into the cervix and to surrounding areas.

Cervical cancer in children is rare. For more information, see the PDQ® summary on Unusual Cancers of Childhood.

Human papillomavirus (HPV) infection is the major risk factor for development of cervical cancer.

Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Talk with your doctor if you think you may be at risk.

Infection of the cervix with human papillomavirus (HPV) is the most common cause of cervical cancer. Not all women with HPV infection, however, will develop cervical cancer. Women who do not regularly have a Pap smear to detect HPV or abnormal cells in the cervix are at increased risk of cervical cancer.

Other possible risk factors include the following:

• Giving birth to many children.
• Having many sexual partners.
• Having first sexual intercourse at a young age.
• Smoking cigarettes.
• Using oral contraceptives ("the Pill").
• Having a weakened immune system.

There are usually no noticeable signs of early cervical cancer but it can be detected early with regular check-ups.

Early cervical cancer may not cause noticeable signs or symptoms. Women should have regular check-ups, including a Pap smear to check for abnormal cells in the cervix. The prognosis (chance of recovery) is better when the cancer is found early.

Possible signs of cervical cancer include vaginal bleeding and pelvic pain.

These and other symptoms may be caused by cervical cancer. Other conditions may cause the same symptoms. Check with your doctor if you have any of the following problems:

• Vaginal bleeding.
• Unusual vaginal discharge.
• Pelvic pain.
• Pain during sexual intercourse.

Tests that examine the cervix are used to detect (find) and diagnose cervical cancer.

The following procedures may be used:

• Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient's health habits and past illnesses and treatments will also be taken.
• Pelvic exam: An exam of the vagina, cervix, uterus, fallopian tubes, ovaries, and rectum. The doctor or nurse inserts one or two lubricated, gloved fingers of one hand into the vagina and places the other hand over the lower abdomen to feel the size, shape, and position of the uterus and ovaries. A speculum is also inserted into the vagina and the doctor or nurse looks at the vagina and cervix for signs of disease. A Pap test of the cervix is usually done. The doctor or nurse also inserts a lubricated, gloved finger into the rectum to feel for lumps or abnormal areas.Pelvic exam. A doctor or nurse inserts one or two lubricated, gloved fingers of one hand into the vagina and presses on the lower abdomen with the other hand. This is done to feel the size, shape, and position of the uterus and ovaries. The vagina, cervix, fallopian tubes, and rectum are also checked.
• Pap smear: A procedure to collect cells from the surface of the cervix and vagina. A piece of cotton, a brush, or a small wooden stick is used to gently scrape cells from the cervix and vagina. The cells are viewed under a microscope to find out if they are abnormal. This procedure is also called a Pap test.Pap smear. A speculum is inserted into the vagina to widen it. Then, a brush is inserted into the vagina to collect cells from the cervix. The cells are checked under a microscope for signs of disease.
• Human papillomavirus (HPV) test: A laboratory test used to check DNA (genetic material) for certain types of HPV infection. Cells are collected from the cervix and checked to find out if an infection is caused by a type of human papillomavirus that is linked to cervical cancer. This test may be done if the results of a Pap smear show certain abnormal cervical cells. This test is also called the HPV DNA test.
• Endocervical curettage: A procedure to collect cells or tissue from the cervical canal using a curette (spoon-shaped instrument). Tissue samples may be taken and checked under a microscope for signs of cancer. This procedure is sometimes done at the same time as a colposcopy.
• Colposcopy: A procedure in which a colposcope (a lighted, magnifying instrument) is used to check the vagina and cervix for abnormal areas. Tissue samples may be taken using a curette (spoon-shaped instrument) and checked under a microscope for signs of disease.
• Biopsy: If abnormal cells are found in a Pap smear, the doctor may do a biopsy. A sample of tissue is cut from the cervix and viewed under a microscope by a pathologist to check for signs of cancer. A biopsy that removes only a small amount of tissue is usually done in the doctor's office. A woman may need to go to a hospital for a cervical cone biopsy (removal of a larger, cone-shaped sample of cervical tissue).

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) depends on the following:

• The patient's age and general health.
• Whether or not the patient has a certain type of human papillomavirus.
• The stage of the cancer (whether it affects part of the cervix, involves the whole cervix, or has spread to the lymph nodes or other places in the body).
• The type of cervical cancer.
• The size of the tumor.

Treatment options depend on the following:

• The stage of the cancer.
• The size of the tumor.
• The patient's desire to have children.
• The patient's age.

Treatment of cervical cancer during pregnancy depends on the stage of the cancer and the stage of the pregnancy. For cervical cancer found early or for cancer found during the last trimester of pregnancy, treatment may be delayed until after the baby is born.

Stages of Cervical Cancer

After cervical cancer has been diagnosed, tests are done to find out if cancer cells have spread within the cervix or to other parts of the body.

The process used to find out if cancer has spread within the cervix or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. The following tests and procedures may be used in the staging process:

• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
• Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram.
• Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
• Cystoscopy: A procedure to look inside the bladder and urethra to check for abnormal areas. A cystoscope is inserted through the urethra into the bladder. A cystoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue samples, which are checked under a microscope for signs of cancer.
• Laparoscopy: A surgical procedure to look at the organs inside the abdomen to check for signs of disease. Small incisions (cuts) are made in the wall of the abdomen and a laparoscope (a thin, lighted tube) is inserted into one of the incisions. Other instruments may be inserted through the same or other incisions to perform procedures such as removing organs or taking tissue samples to be checked under a microscope for signs of disease.
• Pretreatment surgical staging: Surgery (an operation) is done to find out if the cancer has spread within the cervix or to other parts of the body. In some cases, the cervical cancer can be removed at the same time. Pretreatment surgical staging is usually done only as part of a clinical trial.

The results of these tests are viewed together with the results of the original tumor biopsy to determine the cervical cancer stage.

There are three ways that cancer spreads in the body.

The three ways that cancer spreads in the body are:

• Through tissue. Cancer invades the surrounding normal tissue.
• Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
• Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

The following stages are used for cervical cancer:

Carcinoma in Situ (Stage 0)

In carcinoma in situ (stage 0), abnormal cells are found in the innermost lining of the cervix. These abnormal cells may become cancer and spread into nearby normal tissue.

Stage I

In stage I, cancer is found in the cervix only. Stage I is divided into stages IA and IB, based on the amount of cancer that is found.

• Stage IA: Stage IA1 and IA2 cervical cancer. A very small amount of cancer that can only be seen with a microscope is found in the tissues of the cervix. In stage IA1, the cancer is not more than 3 millimeters deep and not more than 7 millimeters wide. In stage IA2, the cancer is more than 3 but not more than 5 millimeters deep, and not more than 7 millimeters wide.A very small amount of cancer that can only be seen with a microscope is found in the tissues of the cervix. Stage IA is divided into stages IA1 and IA2, based on the size of the tumor.
  • In stage IA1, the cancer is not more than 3 millimeters deep and not more than 7 millimeters wide.
  • In stage IA2, the cancer is more than 3 but not more than 5 millimeters deep, and not more than 7 millimeters wide.

• Stage IB is divided into stages IB1 and IB2. Stage IB1 and IB2 cervical cancer. In stage IB1, the cancer can only be seen with a microscopic and is more than 5 mm deep or more than 7 mm wide OR the cancer can be seen without a microscope and is 4 cm or smaller. In stage IB2, the cancer is larger than 4 cm.
  • In stage IB1:
    • the cancer can only be seen with a microscope and is more than 5 millimeters deep and more than 7 millimeters wide; or
    • the cancer can be seen without a microscope and is 4 centimeters or smaller.

  • In stage IB2, the cancer can be seen without a microscope and is larger than 4 centimeters.

Stage II

In stage II, cancer has spread beyond the cervix but not to the pelvic wall (the tissues that line the part of the body between the hips) or to the lower third of the vagina. Stage II is divided into stages IIA and IIB, based on how far the cancer has spread.

• Stage IIA: Cancer has spread beyond the cervix to the upper two thirds of the vagina but not to tissues around the uterus. Stage IIA is divided into stages IIA1 and IIA2, based on the size of the tumor.
  • In stage IIA1, the tumor can be seen without a microscope and is 4 centimeters or smaller.
  • In stage IIA2, the tumor can be seen without a microscope and is larger than 4 centimeters.

• Stage IIB: Cancer has spread beyond the cervix to the tissues around the uterus.

Stage III

In stage III, cancer has spread to the lower third of the vagina, and/or to the pelvic wall, and/or has caused kidney problems. Stage III is divided into stages IIIA and IIIB, based on how far the cancer has spread.

• Stage IIIA: Stage IIIA cervical cancer. Cancer has spread to the lower third of the vagina but not to the pelvic wall.Cancer has spread to the lower third of the vagina but not to the pelvic wall.
• Stage IIIB:Stage IIIB cervical cancer. Cancer has spread to the pelvic wall; and/or the tumor has become large enough to block the ureters (the tubes that connect the kidneys to the bladder). The drawing shows the ureter on the right blocked by the cancer. This blockage can cause the kidney to enlarge or stop working.
  • Cancer has spread to the pelvic wall; and/or
  • the tumor has become large enough to block the ureters (the tubes that connect the kidneys to the bladder). This blockage can cause the kidneys to enlarge or stop working.

Stage IV

In stage IV, cancer has spread to the bladder, rectum, or other parts of the body. Stage IV is divided into stages IVA and IVB, based on where the cancer is found.

• Stage IVA: Stage IVA cervical cancer. Cancer has spread to nearby organs, such as the bladder or rectum.Cancer has spread to nearby organs, such as the bladder or rectum.
• Stage IVB:Stage IVB cervical cancer. Cancer has spread to parts of the body away from the cervix, such as the liver, intestines, lungs, or bones. Cancer has spread to other parts of the body, such as the liver, lungs, bones, or distant lymph nodes.

Recurrent Cervical Cancer

Recurrent cervical cancer is cancer that has recurred (come back) after it has been treated. The cancer may come back in the cervix or in other parts of the body.

Treatment Option Overview

There are different types of treatment for patients with cervical cancer.

Different types of treatment are available for patients with cervical cancer. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment. Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.

Three types of standard treatment are used:

Surgery

Surgery (removing the cancer in an operation) is sometimes used to treat cervical cancer. The following surgical procedures may be used:

• Conization: A procedure to remove a cone-shaped piece of tissue from the cervix and cervical canal. A pathologist views the tissue under a microscope to look for cancer cells. Conization may be used to diagnose or treat a cervical condition. This procedure is also called a cone biopsy.
• Total hysterectomy: Surgery to remove the uterus, including the cervix. If the uterus and cervix are taken out through the vagina, the operation is called a vaginal hysterectomy. If the uterus and cervix are taken out through a large incision (cut) in the abdomen, the operation is called a total abdominal hysterectomy. If the uterus and cervix are taken out through a small incision in the abdomen using a laparoscope, the operation is called a total laparoscopic hysterectomy.Hysterectomy. The uterus is surgically removed with or without other organs or tissues. In a total hysterectomy, the uterus and cervix are removed. In a total hysterectomy with salpingo-oophorectomy, (a) the uterus plus one (unilateral) ovary and fallopian tube are removed; or (b) the uterus plus both (bilateral) ovaries and fallopian tubes are removed. In a radical hysterectomy, the uterus, cervix, both ovaries, both fallopian tubes, and nearby tissue are removed. These procedures are done using a low transverse incision or a vertical incision.
• Radical hysterectomy: Surgery to remove the uterus, cervix, part of the vagina, and a wide area of ligaments and tissues around these organs. The ovaries, fallopian tubes, or nearby lymph nodes may also be removed.
• Modified radical hysterectomy: Surgery to remove the uterus, cervix, upper part of the vagina, and ligaments and tissues that closely surround these organs. Nearby lymph nodes may also be removed. In this type of surgery, not as many tissues and/or organs are removed as in a radical hysterectomy.
• Bilateral salpingo-oophorectomy: Surgery to remove both ovaries and both fallopian tubes.
• Pelvic exenteration: Surgery to remove the lower colon, rectum, and bladder. In women, the cervix, vagina, ovaries, and nearby lymph nodes are also removed. Artificial openings (stoma) are made for urine and stool to flow from the body to a collection bag. Plastic surgery may be needed to make an artificial vagina after this operation.
• Cryosurgery: A treatment that uses an instrument to freeze and destroy abnormal tissue, such as carcinoma in situ. This type of treatment is also called cryotherapy.
• Laser surgery: A surgical procedure that uses a laser beam (a narrow beam of intense light) as a knife to make bloodless cuts in tissue or to remove a surface lesion such as a tumor.
• Loop electrosurgical excision procedure (LEEP): A treatment that uses electrical current passed through a thin wire loop as a knife to remove abnormal tissue or cancer.

Radiation therapy

Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. The way the radiation therapy is given depends on the type and stage of the cancer being treated.

Chemotherapy

Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the cerebrospinal fluid, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). The way the chemotherapy is given depends on the type and stage of the cancer being treated.

See Drugs Approved to Treat Cervical Cancer for more information.

New types of treatment are being tested in clinical trials.

Information about clinical trials is available from the NCI Web site.

Patients may want to think about taking part in a clinical trial.

For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.

Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.

Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.

Patients can enter clinical trials before, during, or after starting their cancer treatment.

Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.

Clinical trials are taking place in many parts of the country. See the Treatment Options section that follows for links to current treatment clinical trials. These have been retrieved from NCI's listing of clinical trials.

Follow-up tests may be needed.

Some of the tests that were done to diagnose the cancer or to find out the stage of the cancer may be repeated. Some tests will be repeated in order to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests. This is sometimes called re-staging.

Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your condition has changed or if the cancer has recurred (come back). These tests are sometimes called follow-up tests or check-ups.

Treatment Options by Stage

A link to a list of current clinical trials is included for each treatment section. For some types or stages of cancer, there may not be any trials listed. Check with your doctor for clinical trials that are not listed here but may be right for you.

Carcinoma in Situ (Stage 0)

Treatment of carcinoma in situ (stage 0) may include the following:

• Loop electrosurgical excision procedure (LEEP).
• Laser surgery.
• Conization.
• Cryosurgery.
• Total hysterectomy for women who cannot or no longer want to have children.
• Internal radiation therapy for women who cannot have surgery.

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with stage 0 cervical cancer. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug. General information about clinical trials is available from the NCI Web site.

Stage IA Cervical Cancer

Treatment of stage IA cervical cancer may include the following:

• Total hysterectomy with or without bilateral salpingo-oophorectomy.
• Conization.
• Modified radical hysterectomy and removal of lymph nodes.
• Internal radiation therapy.

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with stage IA cervical cancer. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug. General information about clinical trials is available from the NCI Web site.

Stage IB Cervical Cancer

Treatment of stage IB cervical cancer may include the following:

• A combination of internal radiation therapy and external radiation therapy.
• Radical hysterectomy and removal of lymph nodes.
• Radical hysterectomy and removal of lymph nodes followed by radiation therapy plus chemotherapy.
• Radiation therapy plus chemotherapy.

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with stage IB cervical cancer. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug. General information about clinical trials is available from the NCI Web site.

Stage IIA Cervical Cancer

Treatment of stage IIA cervical cancer may include the following:

• A combination of internal radiation therapy and external radiation therapy plus chemotherapy.
• Radical hysterectomy and removal of lymph nodes.
• Radical hysterectomy and removal of lymph nodes followed by radiation therapy plus chemotherapy.

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with stage IIA cervical cancer. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug. General information about clinical trials is available from the NCI Web site.

Stage IIB Cervical Cancer

Treatment of stage IIB cervical cancer may include internal and external radiation therapy combined with chemotherapy.

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with stage IIB cervical cancer. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug. General information about clinical trials is available from the NCI Web site.

Stage III Cervical Cancer

Treatment of stage III cervical cancer may include internal and external radiation therapy combined with chemotherapy.

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with stage III cervical cancer. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug. General information about clinical trials is available from the NCI Web site.

Stage IVA Cervical Cancer

Treatment of stage IVA cervical cancer may include internal and external radiation therapy combined with chemotherapy.

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with stage IVA cervical cancer. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug. General information about clinical trials is available from the NCI Web site.

Stage IVB Cervical Cancer

Treatment of stage IVB cervical cancer may include the following:

• Radiation therapy as palliative therapy to relieve symptoms caused by the cancer and improve quality of life.
• Chemotherapy.
• Clinical trials of new anticancer drugs or drug combinations.

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with stage IVB cervical cancer. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug. General information about clinical trials is available from the NCI Web site.

Treatment Options for Recurrent Cervical Cancer

Treatment of recurrent cervical cancer may include the following:

• Pelvic exenteration followed by radiation therapy combined with chemotherapy.
• Chemotherapy as palliative therapy to relieve symptoms caused by the cancer and improve quality of life.
• Clinical trials of new anticancer drugs or drug combinations.

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with recurrent cervical cancer. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug. General information about clinical trials is available from the NCI Web site.

To Learn More About Cervical Cancer

For more information from the National Cancer Institute about cervical cancer, see the following:

• Cervical Cancer Home Page
• What You Need to Know About Cancer of the Cervix
• Cervical Cancer Prevention
• Cervical Cancer Screening
• Unusual Cancers of Childhood
• Drugs Approved to Treat Cervical Cancer
• Cryosurgery in Cancer Treatment: Questions and Answers
• Lasers in Cancer Treatment
• Understanding Cervical Changes: A Health Guide for Women
• Human Papillomavirus (HPV) Vaccines
• Pap and HPV Testing

For general cancer information and other resources from the National Cancer Institute, see the following:

• What You Need to Know About Cancer
• Understanding Cancer Series: Cancer
• Cancer Staging
• Chemotherapy and You: Support for People With Cancer
• Radiation Therapy and You: Support for People With Cancer
• Coping with Cancer: Supportive and Palliative Care
• Questions to Ask Your Doctor About Cancer
• Cancer Library
• Information For Survivors/Caregivers/Advocates

Changes to This Summary (09/18/2012)

The PDQ® cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

Editorial changes were made to this summary.

Get More Information From NCI

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