This timely book, published just as cancer immunotherapy comes of age, summarizes the rationale, present status, and future perspective for cancer immunotherapy. Included are explanations of the constitution of the immune system and immunocheckpoints, the mechanism of antigen presentation and recognition, valuable modalities, clinical trials and guidance, personalization, and biomarkers, all of which are essential for understanding the success of cancer immunotherapy. This innovative therapy has been investigated worldwide as the fourth line of cancer treatment after the standard treatments of surgery, chemotherapy, and radiotherapy. The progress in fundamental understanding of tumor immunology and the recent advances in clinical trials have opened new avenues with a cancer vaccine in 2010 and immunocheckpoint modulation in 2011, with their approval already granted in the United States. Today, there are no doubts, even among experts in cancer chemotherapy and radiotherapy, that the immune system plays a vital role in tumor eradication. Following American approval, many clinical trials of cancer immunotherapy are being conducted. With this book the reader will readily understand the paradigm shift in cancer treatment and will realize the importance of cancer immunotherapy. The great value of immunotherapy will be obvious, not only for tumor shrinkage but for prolonging patient survival.