Screening tests can help to find cancer at an early stage, before recognizing the symptoms. When abnormal tissue or cancer is found early, it may be easier to treat or cure. The main aim of cancer screening is to reduce the mortality rate. Each type of cancer has its own screening test through which the pathologist can identifies the precancerous or cancerous cells. Lung cancer is screened by using spiral computed tomography technique. Mammography and Magnetic resonance imaging methods are used to screen the breast cancer. Human Papillomavirus testing and pap test are used to find out the cervical cancer. The techniques practice to screen the colorectal cancer are colonoscopy, sigmoidoscopy and fecal occult blood test. Screening tests must be safe, well-tolerated and effective with appropriately low rates of false positive and false negative results. Screening has many risks such as over diagnosis, false positives, increased testing and false assurance.