 We explain cancer and why prevention is so important. This is Chris. He never liked going to the doctor, so in the past he's tried to avoid it. But then his uncle gets lung cancer and passes away. And then someone else he knows is diagnosed with cancer. He starts to get really worried. What is cancer exactly? Cancer is one of the most common causes of death around the world. It happens because of a very natural process that's necessary for life, cell division. The human body consists of billions of cells. These multiply all the time. That's how we grow and replenish dead cells. That happens countless times every day. Every now and then cells are created that aren't quite according to plan. But that's also entirely normal and very common. Most of those cells die off. But sometimes, if one of those mutated cells has an advantage over the others, it multiplies and can crowd out the healthy cells, kind of like weeds in a garden. These cells can form tumors, which can then scatter into other organs, similar to a dandelion that spreads its seeds across an entire lawn. That's called metastasizing. The more often the cancer metastasizes, the lower the person's chances of recovering. Cancer can appear anywhere in the body. The most common types are skin cancer, colon cancer, lung cancer, and breast cancer. It can affect any of us. The older we get, the more cells need to divide. That's why tumors appear in older people more often. So Chris could develop cancer someday as well. However, if he exercises often and decides that an unhealthy lifestyle isn't for him, the risk is much lower. In particular, smoking can harm genetic material and cause nasty cancer cells. So that's why not smoking is the most important step for prevention. To treat cancer, doctors eliminate the tumors by surgically removing them, subjecting them to radiation, or using medicine to stop their growth. The options available and the success rate of treatment depend on the type of cancer, but also depend strongly on how early it's identified. That's why it's not just important that Chris refrains from smoking. He also needs to get the recommended cancer screenings. They only take a small amount of effort, and it's well worth it later for Chris and his family.