Minimally invasive techniques are now being used to find metastasis in breast cancer and melanoma. As it turns out, the lymphatic drainage of a specific area of breast usually drains to a specific lymph node, which is the lymph node most likely to contain cancer if the breast cancer has become metastatic. Lymphatic dye and radioactive sulfur colloid are injected around the area of the breast cancer, and the dye and colloid travel through lymph channels to this lymph node. Using a gamma counter probe, the lymph node containing the radioactive substance is identified through a small incision. In most cases, this procedure can replace the larger axillary incision and complete lymph node dissection performed in the past. A similar procedure is performed for melanomas.