How does small cell lung cancer affect the body?

Small cell lung cancer starts in the lungs, where mutated cancer cells begin to form tumors. But like all cancers, small cell lung cancer can spread to any organ or area of your body; this process is known as metastasis. The cancerous cells are defined by the fact that they grow uncontrollably, and so if left untreated the cancerous cells from small cell lung cancer can continue to grow. By traveling through blood vessels, the lymph system, or surrounding tissue, it can spread to even remote places in your body.