Pathologists use the term isolated tumours cells (ITCs) to describe a small group of tumour cells found in a lymph node. To meet this definition, the group of tumour cells usually has to be less than 200 total cells or smaller than 0.2 mm. The cells have usually spread to the lymph node from a cancerous tumour located somewhere else in the body. The movement of cells from the primary tumour to another part of the body is called metastasis. Normally, finding tumour cells in a lymph node is associated with an increase in the pathologic nodal stage and a worse prognosis. However, research has shown that isolated tumour cells are not associated with a worse prognosis for some types of breast, uterine, and colon cancer. For this reason, staging systems exclude isolated tumour cells when determining the nodal stage for these types of cancers.