Cancer Definition. Cancer is a wide range of diseases that form a subset of neoplasm. A tumor is a group of neoplasms that have undergone unregulated growth. The neoplasm does not perform any physiological functions and often forms a mass. Cancer can result from genetic origins inherited from ancestors. It is possible to be born with specific genetic mutations or a defect in a certain gene that makes the person more likely to develop cancer later in life. Classification of cancer today, types of primary cells in the tumor. One of the important factors in sorting a tumor as benign or malignant is its impact potential. If a tumor does not have the control to invade neighboring tissues or spread to distant positions by metastasis, then it is benign. While metastatic tumors are malignant and can influence neighboring sites. The development rates of benign and malignant tumors also differ; benign tumors grow remarkably more slowly than malignant tumors. The appearance of benign tumors is generally identical and malignant tumors are often different from those of cellular origin. After this classification, tumors are divided based on different cell types. More importantly, carcinomas, characterized by specific cells commonly found in internal and external parts of the body, for example lung, breast and colon cancer. Cancer formation cascade and causes of cancer. Cancer is formed by a mutation in cells. . Stem cells divide to produce more cells called progenitor cells. These cells then divide and develop into differentiated cells with specific functions. However, a mutation occurs here which causes the cells to dedifferentiate and a series of mutant events occur...... middle of paper ...... a large tumor that feeds on blood vessels. When a drug is used to kill cancer cells, some cells will be resistant to it. This causes the surviving cells to multiply and create a whole new colony that is resistant to that specific drug. Symptoms and treatments. The signs and symptoms of cancer are very different and depend on where the cancer is, how deep it is, and how big it is. the tumor is. Some cancers can be felt or visible through the skin, for example a bump on the outer wall can be an indicator of cancer in these areas. Other types of cancer have less physical signs. For example, colon cancers cause symptoms such as constipation, diarrhea, and changes in the shape and color of stools. Bladder or prostate cancer affects bladder function, such as more persistent or unusual urination.