Im a senior in high school and have been chewing since the middle of freshman year and i was wondering if its common for a teenager to get oral cancer?

As you get older: The risk increases as you get older. The number of years you do the insult, it increases the risk. The sooner you stop, the sooner the insult stops. It typically takes years to see the result of the insult to the tissue, and the reason you don't typically diagnose these cancers till a few decades later. Best thing to do is stop now.

It is not common: While it is not common for a teenager to get oral cancer, it is much more common for people who chew tobacco products to get oral cancer than those who don't chew. Be smart, quit now!