A tumor is a mass or lump of tissue that may resemble swelling. Not all tumors are cancerous, but it is a good idea to see a doctor if one appears. A tumor is an abnormal growth of cells that serves no purpose. The exact cause of a benign tumor is often unknown. It develops when cells in the body divide and grow at an excessive rate. Tumor is used as a synonym for neoplasm. Cells start to grow uncontrollably. These cells may form a mass called a tumor. A tumor can be cancerous or benign. Tumor necrosis is often limited to a small area within the sample. Its presence suggests a more aggressive breast cancer. Hypoxia is a marker of more aggressive tumors and tumor necrosis was significantly associated with features such as high histologic grade, vascular invasion by tumor cells and reduced survival. Tumor necrosis was defined as areas of necrotic tumor cells immediately adjacent to viable tumor tissue .Tumor necrosis factor (TNF) is a multifunctional cytokine that plays important roles in diverse cellular events such as cell survival, proliferation, differentiation, and death. Designer antibodies fight cancer by tethering immune cells to tumor ... the antibody shrank fast-growing non-Hodgkin lymphoma tumors. Neoplasms or tumors can be cancerous or non-cancerous and can grow in any part of the body.