Electron micrograph (EM) of a human, breast cancer tumor cell. Metastasis of such tumors through the lymphatic system to axillary lymph nodes and to bone, lung, brain, and liver is common, but there is evidence that primary carcinomas of the breast may exist in multiple sites, and that tumor cells may enter the bloodstrea directly, without passing through the lymph nodes. Surgical treatment, depending on the assessment of the tumor, may be a radical, modified or simple mastectomy with dissection of axillary nodes, or lumpectomy. Postoperative radiotherapy, chemotherapy, or both are usually prescribed. Mag., 4600x.