More than 9000 kids get cancer in the US every year (about 1 in 450). The most common are leukemias, lymphomas, and brain tumors, but there are many different kinds. If you would like up to date numbers, the  AAP has them here.

Cancer is a group of more than 100 diseases caused by the cells in a person’s body multiplying out of control. Cancer is separated into different types depending on what sort of cell it originated from (blood, brain, lung…) and if it invaded nearby body parts (a tumor) or spread to other organs (metastasis). That might be a smidge simplified, but you get the idea.

Your children’s genes, the DNA they inherit from you, influence their risk of cancer–not something you can change. But lifestyle and environment also influence their risk, and there you can have an impact.

That impact includes not only your kid’s exposures in childhood, but also the example they see in your behavior and the habits you establish that will carry forward into their adult lives. What you teach them in childhood can protect them throughout their lives.

What to do to lower your child’s risk of getting cancer:

1. First, the obvious one: don’t use tobacco, and don’t allow anyone else to smoke around your kids. I know, easier said than done, but an estimated four out of five cancers are caused by tobacco. The poisons in tobacco damage DNA, increasing the incidence of 14 different cancers including lung, some leukemias, voice box, throat, liver, kidney… Secondhand smoke alone increases cancer risk by 25%. The sidestream smoke off the burning end of a cigarette has 3 times the carbon monoxide, 10 times the nitrosamines and hundreds of times the ammonia of exhaled smoke. Add to this that if you smoke, your child’s chances of becoming a daily addicted smoker increase by 25 times, boosting their risk even more. Just don’t. No excuse is good enough.
2. Also well known: protect them from sunburns to prevent skin cancer. Use at least SPF15 and reapply through the day. Seek shade during peak hours. Stick a hat on their head that shades their face, and a pair of sunglasses on their nose.
3. Feed them a healthy diet with lots of fiber, fruits and vegetables. Avoid processed meats and an overabundance of red meat and salt. A healthy diet helps your body remove harmful chemicals, prevent and repair damage to DNA, and block the formation of cancer causing chemicals. A less healthy diet has been linked to breast, mouth, esophagus and GI cancers.
4. Encourage exercise. Exercise stabilizes levels of hormones like estrogen and insulin that have been linked to cancer. An active lifestyle decreases the incidence of breast, bowel, and uterine cancers.
5. Keep them at a healthy body weight. Fatty tissue produces hormones that influence the way cells grow. Cell overgrowth is at the root of cancers. Obesity has been linked to breast cancer, esophageal and bowel cancers, and liver, kidney, pancreas and uterine cancers.
6. Limit their exposure to chemicals. Indoor pesticides have recently been shown to  increase children’s risk of leukemia by 47%. Be aware of the chemicals you might be exposed to at your job, wear appropriate safety gear, and don’t bring poisons home on your clothes–cancer causing chemicals such as arsenic, benzene, and asbestos are still used in industry. Check the use instructions (do they need to be used in a well ventilated area?) and ingredients in the products you do use at home. You can check for harmful ingredients in household products at nih.gov. Store household chemicals such as cleaners, paints, degreasers, and strippers safely high up and locked away.
7. In the “be a good example” category: limit your alcohol consumption. Alcohol increases the amount of cancer causing chemicals in your body, and affects hormone levels. It also amplifies the toxic effects of tobacco. Drinking alcohol increases your risk of breast, mouth, throat and bowel cancers.
8. Avoid certain kinds of infections. Infection can increase cancer risk by causing chronic inflammation and suppressing the immune system. Hep B increases your kid’s risk, so get them the vaccine, and teach them to avoid iv drugs and indiscriminate sex. Be careful with tattoos: Hep C also increases risk, and 41% of it comes from tattoos. Helicobactor pylori  increases cancer risk–doctors look for it with reflux disease, gastritis and ulcers.  Human Papillomavirus  works by causing cells to divide rapidly (hence the appearance of a wart). We lose 4000 women to preventable cervical cancer yearly, and the incidence of oral cancers due to HPV is increasing dramatically. The CDC recently announced that the vaccine has decreased the incidence of HPV in teens by 2/3. Get your child the HPV vaccine when he or she hits 11 or 12.

Cancer risk factors seem to hit the hardest when a baby is still in the womb, and in adolescence when their bodies are rapidly growing and changing, so these are the times when a parent can absolutely have an effect in preventing cancer.

A healthy lifestyle stacks the deck in your child’s favor, dramatically decreasing their odds of getting cancer. Protect them from cancer causing sunburns and poisons, get those vaccines, establish good habits, and be a good example. There is no down side to a healthy diet, regular exercise, and limiting their exposure to toxins, and it may increase their chances of hanging around for a while.