Tumor, also known as neoplasm, is a mass or group of tissues that is formed as a result of abnormal growth. It can appear anywhere on the body. Bone, tissues, skin, glands, and organs, all can be affected by tumors. They may be cancerous (malignant), non-cancerous (benign), or precancerous. Malignant tumors can spread to adjacent tissues, glands, or other body parts. Benign tumors pose a low risk of death. They are isolated and do not spread to other body parts or impact neighboring tissues. Precancerous tumors are non-cancerous tumors which may become cancerous if left untreated. Most common types of cancer treatments include targeted therapy (molecularly targeted therapy), hormonal therapy and cytotoxic therapy. There exist two types of targeted therapies, namely, small molecule medicines and monoclonal antibodies. The small molecule medicines are biopharmaceuticals that are so small that they can enter the cancer cells and destroy them. Targeted therapy makes use of monoclonal antibodies which cannot enter into the cells. However, these monoclonal antibodies attack targets outside of cells. In various cases, monoclonal antibodies are used to launch chemo and radiation straight into tumors. This book aims to provide the readers a comprehensive overview of the applications of targeted therapies for the treatment and management of tumors. For all readers who are interested in understanding this therapeutic procedure, it will serve as an excellent guide.