The requirement for computerization of detection of lung cancer disease arises ever since recent-techniques which involve manual-examination of the blood smear as the first step toward diagnosis. This is quite time-consuming, and their accurateness depends upon the ability of operator's. So, prevention of lung cancer is very essential. This paper has surveyed various techniques used by previous authors like ANN (Artificial Neural Network), image processing, LDA (Linear Dependent Analysis), SOM (Self Organizing Map) etc.