Cancer is a devastating disease that affects almost all ages. Basically, cancer cells are those cells which have lost the usual control over their growth and division. They are characterized by immortalization, transformation and metastasis. Metastasis actually distinguishes a malignant tumor (ability to invade normal tissue) from a clinically benign tumor (do not invade normal tissue). Tumor formation may be spontaneous or induced by carcinogens or tumor viruses. On molecular basis it is caused by activation of oncogenes, loss of function of tumor suppressor genes, deregulation of DNA repair and genomic stability genes