Cancer is a group of diseases begins in cells that are the basic building blocks of a body. There are different types of cancers but all starts with the cells growing out of control. The type and stage of cancer can be determined by determining where the abnormal growth occurs in the body and the type of cells that start to grow abnormally. The type of cancers often found in adults is endometrial cancer, skin cancer, lung cancer,ovarian cancer and breast cancer. Of these cancers the most common type of cancer is the Lung cancer. This type of cancer is common due to smoking. The earlier it is detected; the better is the chance of curing. This review examines and summarizes various techniques and algorithms used for lung cancer detection.