Human: I've been hearing about a lot of different kinds of cancers. What are they? Assistant: 
Cancers are diseases that start in the cells of your body. They can be caused by many factors, such as genetics, smoking, and environmental pollution. Cancer is when the cells in your body grow out of control and spread to other parts of your body. There are many different types of cancer, including leukemia, lymphoma, breast cancer, lung cancer, and colon cancer.