If you are diagnosed with cancer, your doctor will need to know if the cancer has spread from its primary site to nearby lymph nodes or to other parts of the body. This assessment of the spread of a cancer is known as staging and may involve surgery and imaging tests. Staging allows doctors to plan the best treatment and to determine the prognosis.
The first part of staging involves measuring the size of the tumour assessing the extent of its invasion into nearby tissues. A biopsy may be performed, in which a sample of tissue is taken from the tumour and examined, or the whole tumour may be removed for examination.
If a cancer spreads, it often first affects nearby lymph nodes, causing them to enlarge. Cancer in lymph nodes can be detected by examination under a microscope after surgical removal or by imaging techniques such as CT scanning.
If cancer cells enter the bloodstream, metastases (secondary tumours) may develop in other parts of the body. Imaging of the most common sites of metastases, such as the liver, lungs, and bones, may therefore be performed after a primary tumour is diagnosed.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.