Staging: Questions and Answers, Fact Sheet 5.32
- What is staging?
Staging describes the extent or severity of an individualís cancer based on the extent of the original tumor and the extent of spread in the body. Staging is important:
- Staging helps the doctor plan a personís treatment.
- The stage can be used to estimate the personís prognosis.
- Knowing the stage is important in identifying clinical trials that may be suitable for a particular patient.
Staging helps researchers and health care providers exchange information about patients. It also gives them a common language for evaluating the results of clinical trials and comparing the results of different trials.
Staging is based on knowledge of the way cancer develops. Cancer cells divide and grow without control or order to form a mass of tissue, called a growth or tumor. As the tumor grows, it can invade nearby organs and tissues. Cancer cells can also break away from the tumor and enter the bloodstream or lymphatic system. By moving through the bloodstream or lymphatic system, cancer can spread from the primary site to form new tumors in other organs. The spread of cancer is called metastasis.
Staging systems for cancer have evolved over time. They continue to change as scientists learn more about cancer. Some staging systems cover many types of cancer; others focus on a particular type. The common elements considered in most staging systems are:
- Location of the primary tumor,
- Tumor size and number of tumors,
- Lymph node involvement,
- Cell type and tumor grade*, and
- Presence or absence of metastasis.
*Information about tumor grade is available in the NCI fact sheet Tumor Grade: Questions and Answers, which can be found at http://cis.nci.nih.gov/fact/5_9.htm on the Internet.
The TNM system is one of the most commonly used staging systems. This system has been accepted by the International Union Against Cancer and the American Joint Committee on Cancer. Most medical facilities use the TNM system as their main method for cancer reporting. PDQģ, the NCIís comprehensive cancer database, also uses the TNM system.
The TNM system is based on the extent of the tumor , the extent of spread to the lymph nodes , and the presence of metastasis . A number is added to each letter to indicate the size or extent of the tumor and the extent of spread.
|TX||Primary tumor cannot be evaluated|
|T0||No evidence of primary tumor|
|Tis||Carcinoma in situ|
|T1, T2, T3, T4||Size and/or extent of the primary tumor|
|Regional Lymph Nodes|
|NX||Regional lymph nodes cannot be evaluated|
|N0||No regional lymph node involvement|
|N1, N2, N3||Involvement of regional lymph nodes|
|MX||Distant metastasis cannot be evaluated|
|M0||No distant metastasis|
For example, breast cancer T3 N2 M0 refers to a large tumor that has spread outside the breast to nearby lymph nodes, but not to other parts of the body. Prostate cancer T2 N0 M0 means that the tumor is located only in the prostate and has not spread to the lymph nodes or any other part of the body.
For many cancers, TNM combinations correspond to one of five stages. Criteria for stages differ for different types of cancer. For example, bladder cancer T3 N0 M0 is stage III; however, colon cancer T3 N0 M0 is stage II.
|Stage 0||Carcinoma in situ.|
|Stage I, Stage II, and Stage III||Higher numbers indicate more extensive disease: greater tumor size, and/or spread of the cancer to nearby lymph nodes and/or organs adjacent to the primary tumor.|
|Stage IV||The cancer has spread to another organ.|
Question 7 describes sources of additional information about staging for specific types of cancer.
Many cancer registries, such as the NCIís Surveillance, Epidemiology, and End Results Program, use summary staging. This system is used for all types of cancer. It groups cancer cases into five main categories:
- In situ is early cancer that is present only in the layer of cells in which it began.
- Localized is cancer that is limited to the organ in which it began, without evidence of spread.
- Regional is cancer that has spread beyond the original site to nearby lymph nodes or organs and tissues.
- Distant is cancer that has spread from the primary site to distant organs or distant lymph nodes.
- Unknown is used to describe cases for which there is not enough information to indicate a stage.
The types of tests used for staging depend on the type of cancer. Tests include the following:
- Physical exams are used to gather information about the cancer. The doctor examines the body by looking, feeling, and listening for anything unusual. The physical exam may show the location and size of the tumor and the spread of the cancer to the lymph nodes and/or to other organs.
- Imaging studies produce pictures of areas inside the body. These studies are important tools in determining stage. Procedures such as x-rays, computed tomography scans, magnetic resonance imaging scans, and positron emission tomography scans can show the location of the cancer, the size of the tumor, and whether the cancer has spread.
- Laboratory tests are studies of blood, urine, other fluids, and tissues taken from the body. For example, tests for liver function and tumor markers can provide information about the cancer.
- Pathology reports may include information about the size of the tumor, the growth of the tumor into other tissues and organs, the type of cancer cells, and the grade of the tumor. A biopsy may be performed to provide information for the pathology report. Cytology reports also describe findings from the examination of cells in body fluids.
- Surgical reports tell what is found during surgery. These reports describe the size and appearance of the tumor and often include observations about lymph nodes and nearby organs.
The doctor most familiar with a patientís situation is in the best position to provide staging information for that individual. For background information, PDQ, the NCIís cancer information database, contains cancer treatment summaries that describe the staging of each type of cancer. PDQ treatment summaries are available at http://www.cancer.gov/cancerinfo/pdq/ on the NCIís Web site.
Staging information can also be obtained by calling the NCIís Cancer Information Service toll-free at 1Ė800Ė4ĖCANCER. For deaf and hard of hearing callers with TTY equipment, the toll-free number is 1Ė800Ė332Ė8615. CIS information specialists also offer immediate online assistance through the Help link at http://www.cancer.gov/ on the Internet.