Cancer

Cancer is a group of diseases characterized by uncontrolled growth of tissue cells in the body and the invasion by these cells into nearby tissue and migration to distant sites. Cells are the building blocks of living things.
Cancer grows out of normal cells in the body. Normal cells multiply when the body needs them, and die when the body doesn't need them. Cancer appears to occur when the growth of cells in the body is out of control and cells divide too quickly. It can also occur when cells forget how to die.
There are many different kinds of cancers. Cancer can develop in almost any organ or tissue, such as the lung, colon, breast, skin, bones, or nerve tissue.

Endocrine tumours

Endocrine tumors are abnormal growths in endocrine glands. Since endocrine glands produce hormones, tumors of endocrine glands also produce hormones. These hormones are produced in excessive amounts by endocrine tumors and then released into the blood.
The excessive amounts of hormones in the blood produce markedly abnormal effects on the body. For example in normal individuals insulin is secreted from pancreatic islet cells in just the right amount to keep your blood sugar levels within normal limits. In patients with insulin producing islet cell tumors of the pancreas, excessive insulin is produced in the blood that cause large decreases in blood sugar levels so that patients suffer from severe effects of low blood sugar.