Symptoms of metastatic breast cancer vary greatly depending on where the cancer has metastasized. Metastatic breast cancer can spread to the bones, lungs, brain and liver, all of which can have different symptoms. If metastasis occurs in the lungs, it can cause a range of symptoms that may include: chest pain or discomfort, coughing, sputum, and wheezing. This is mainly due to the nerve pain and discomfort caused by the invasion of the pleura after breast cancer metastasis. Metastasis to the lung itself can irritate the respiratory tract causing symptoms such as coughing, shortness of breath, and wheezing, and cancer cells can collect in the pleural cavity around the lung. As breast cancer spreads, increased fluid gradually accumulates in the pleura, a condition known as pleural effusion. When this condition occurs, it can further aggravate the symptoms of labored breathing, shortness of breath, wheezing, and chest pain. After breast cancer metastasizes to the lungs, there may also be infiltrative growth of cancerous tissue in the lungs, causing bleeding from broken mucous membranes of tiny bronchi, resulting in hemoptysis and mucus. When observing the symptoms of breast cancer, it is difficult to distinguish between the symptoms of breast cancer lung metastasis and those of the common cold or upper respiratory tract infection. This is especially true during cold and flu prone seasons or when the patient has a history of breathing problems. During the examination, if the doctor suspects lung metastasis from breast cancer, he or she may order imaging tests such as a CT scan of the chest. Therefore, in case of breast cancer metastasis it is important to treat the symptoms according to the different sites of metastasis.