Dr. Alex Marson, MD, PhD, is a professor of medicine at the University of California, San Francisco. We discuss the biology of the immune system and cancer, and everyday choices that can increase or decrease your cancer risk, several of which are surprising but all of which are actionable. We also discuss immunotherapy, including how engineered T-cells can be used to defeat childhood and adult cancers. Dr. Marson explains CRISPR and gene editing to cure diseases, and we address the ethical