If it's asking for two ways that can cause cancer heres two ways. And heres two ways that it can be avoided.
1) Lung Cancer- Smoking can cause lung cancer. Ways to prevent it: Don't start smoking or if you are smoking, start to stop smoking and get healthy lungs back. Prevent second hand smoking.
2) Liver Cancer- Caused by drinking alcohol. Can be prevented by not over drinking or not drinking at all
