- What is staging?
Staging describes the extent or severity of an individual’s cancer based on the extent of the original (primary) tumor and the extent of spread in the body. Staging is important:
- Staging helps the doctor plan a person’s treatment.
- The stage can be used to estimate the person’s prognosis (likely outcome or course of the disease).
- Knowing the stage is important in identifying clinical trials (research studies) 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.
- What is the basis for staging?
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.
- What are the common elements of staging systems?
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 (spread of cancer into lymph nodes),
- Cell type and tumor grade* (how closely the cancer cells resemble normal tissue), 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://www.cancer.gov/cancertopics/factsheet/Detection/tumor-grade on the Internet.
The Web site of the National Cancer Institute (http://www.cancer.gov)
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