Having lung cancer or a history of lung cancer, is the cause for lung cancer metastases. Cancer that metastasizes to the lungs is a life-threatening condition that develops when cancer in another area of the body (primary organ such as breast), spreads to the lung. Prevention of metastatic lung cancer can be done by avoiding the risk factors of primary lung cancer such as smoking or chewing tobacco, or prompt and successful treatment of your primary cancer. Awareness, early detection and timely treatment are vital for preventing the spread of lung cancer.