If left untreated, breast cancer can spread to the lungs, according to the National Breast Cancer Foundation. Metastatic breast cancer can also spread to the liver, brain or bones.
When breast cancer travels from the breast to the lungs, the cancer is classified as stage 4 breast cancer, notes the National Breast Cancer Foundation. Metastasis to the lungs can cause a variety of different issues, including chest pain, chronic cough, abnormal chest x-rays and shortness of breath. Breast cancer metastasis to the lungs can also cause weight loss, fatigue, poor appetite and other symptoms.
Breast cancer spreads by invading healthy cells nearby, reports the National Breast Cancer Foundation. Once healthy cells are invaded, cancer cells can infiltrate the lymph or circulatory system and travel to other parts of the body. Cells that become lodged in distant capillaries begin to divide and invade the tissue surrounding them, forming new tumors. These new tumors are known as micrometastases.
Other signs to look for when it comes to distal breast cancer sites include swelling, progressive pain and bones that are broken easily when breast cancer metastasizes to the bones, according to the National Breast Cancer Foundation. Breast cancer traveling to the brain can cause seizures, vision disturbances and headaches, while metastasis to the liver can result in jaundice, high liver enzymes, vomiting and loss of appetite.