It is quite perplexing yet true that a cancerous growth can start developing anywhere in the human body, which is primarily made up of trillions of cells. When you get cancer, the orderly process of the cells in your body gets disrupted. Cancer cells are abnormal cells, and these cells live on even when they become old or damaged. New cells are formed even when they are not needed by the body and they keep dividing without stopping. The extra cells form tumours. Cancerous tumours may be malignant or benign.