Our bodies are made up of cells. Within each cell are genes that direct and control all the cell's functions and determines how and when it divides and grows. Normal cells divide and grow at a controlled rate. How fast or slow a cell divides and grows, and what it does, depends on the genes within that cell.
Cancer begins as a change in the gene of a single normal cell in any part of the body. This then affects the set of instructions in the gene and the cell no longer acts normally.
What triggers a change in the gene is still largely unknown. However, smoking, alcohol, and certain chemicals are known to promote a change in the gene.
Cancer can also be called a neoplasm, tumour or malignancy. A tumour is a swelling and is described to be either benign (a growth that does not spread to other parts of the body) or malignant (a cancer that spreads from its original site into surrounding tissue and other parts of the body).
When cancer spreads, the new tumour has the same abnormal cells and the same name as the original cancer. For example, if lung cancer spreads to the liver, the cancer cells in the liver are still lung cancer cells. The disease is then called metastatic lung cancer, not liver cancer.
