Why does breast cancer often spread to the lung?

摘要

Breast cancer is the most commonly diagnosed cancer among women and the second leading cause of cancer-related deaths in women. In 2014, it is estimated that there will be over 230,000 new cases of breast cancer diagnosed in the USA alone [1]. When breast cancer is confined to the breast tissue or regions slightly beyond the breast, traditional methods of treatment (surgery, radiation) are fairly successful, with overall 5-year survival rates of 98.6% for localized breast cancer and 84.4% for regional breast cancer [1,2]. However, the majority of deaths associated with breast cancer are not due to the initial tumor but rather to metastatic disease, the process by which cancer spreads from an initial site of development to distant sites throughout the body. Following metastasis, overall 5-year survival declines considerably to 24.3%, representing a major problem in breast cancer patients. This substantial drop in survival is largely due to the ineffectiveness of current treatments in the metastatic setting [1,2].