This intraabdominal growth may cause bowel or ureteral obstruction. Cancer can also spread to adjacent structures and penetrate body cavities by direct extension. Malignant tumors differ from the benign ones in their ability to metastasize, or spread from the primary site to other locations in the body. From there, they proliferate and infiltrate the organ tissue and grow into new tumor deposits. Patterns of metastasis differ from one cancer to another.
Cancers tend to metastasize to specific organs or sites in the body.
Clinical symptoms and problems vary according to the organ involved and the extent of disease. A brief overview of the primary disease and the likely sites of metastatic spread are presented here. In addition to the local effects of tumor growth, cancer can produce systemic signs and symptoms that are not direct effects of either the tumor or its metastases. These manifestations are collectively referred to as paraneoplastic syndromes. Many of these syndromes involved ectopic hormone production by tumor cells or the secretion of biochemically active substances that cause metabolic abnormalities.