I have only known of Corn Starch as a thickener, but you could also use regular baking flour. You can get non-bleached flour and use that instead of the corn starch. I think that corn starch is non-modified. But if it is not, the flour is usually the go-to. The formula for using measures of the flour is a two-to-one to corn starch. I think that you need to add the flour slowly to make sure that you don't surpass the thickness you want to achieve. You need to stir it in carefully so it does not bulk up on itself.
I usually used Cornstarch when needing to thicken a recipe. As long as the recipe needs to be cooked ~ this takes the starchy corn taste out of your dish.
Glutinous rice flour - works identical to corn starch but is freeze-stable and will never break from over cooking. You can usually get it for 99 cents a pound at asian markets.