Cancer is not a single disease but a group of diseases, resulting from the presence and uninhibited growth of abnormal cells in our body. These may be present anywhere. These abnormal cells, together, form a tumour. Tumours that are dormant and do not spread are seldom dangerous. However, once the abnormal cells start invading neighboring cells, they are considered to be malignant tumours. These malignant tumours are the cause for cancer, one of the deadliest groups of diseases in the world. However, Medicine has made much progress and now, through early detection, we are able to control the effect, if not cure the cancer altogether.