Cancer (neoplasia) is a transformation of normal cells into abnormal malignant cells, and it can take many forms. Some involve solid masses, or tumors, while others involve the blood or bone marrow in leukemia. Cancer can develop in virtually any organ or body system.
In addition, some cancers spread or metastasize to other areas of the body. They can spread to nearby tissues, or invade the blood stream or lymphatic system. Cancer commonly metastasizes to the lung. The exact symptoms, treatment and prognosis vary with the specific tumor type and situation.
For more information about a specific type of cancer, use the search engine and look for the specific cancer you are interested in.