Whether or not you can substitute a cake pan for a pizza pan depends largely upon what type of pizza you're making. Some pizzas will work well in cake pans, while others will not. As long as your recipe plays to a pan's strengths, your pizza should turn out the same as if you had used a pizza pan.
If you're baking a deep-dish, stuffed or other thick-crust pizza, substituting a cake pan in place of a pizza pan is no problem. Both these type of pizza pans and cake pans are sold in the same diameters, and have sides that are the same height. In most cases, they're completely interchangeable. Pan diameter will have a greater effect on your pizza recipe than whether or not it's labeled as a cake or pizza pan. The diameter directly affects the size of the pizza, as well as the amount of topping you use. Choose a cake pan that is the same diameter as the pizza pan for which you're substituting.
Cake and pizza pans come in diameters that range from 6 inches to 18 inches, in 2-inch increments. If you visit professional restaurant supply shops, you may be able to find larger pizza pans, but they won't fit inside most home ovens. The walls of these pans are usually 2 inches high. This enables them to support both thick-crust pizzas and cakes as they're baking, without ingredients overflowing over the tops of these pans.
Thin-crust pizza requires a pan with little or no side wall. For a very crispy crust, try baking with a perforated pan -- or with no pan at all, using a pizza stone. These types of pizzas will not bake well in a deep-dish pizza pan or a cake pan. Thick-crust pizzas usually have a chewy crust rather than a crisp, flaky one, partly because the walls of the pan help keep moisture inside the dough as it bakes. Thin-crust pizzas, by comparison, allow more moisture to escape from the dough as it bakes, which results in a crisper crust.
Bake pizza in a cake pan the same way you would in a pizza pan. It's unnecessary to grease and flour it or use parchment paper, the way you would with a cake. If you're making a pizza with very strongly flavored ingredients, such as anchovies, wash the pan thoroughly after you bake the pizza in it. If necessary, wash the pan several times to get rid of the smell. If the smell lingers, it may give cakes and other items baked in that pan in the future a bad flavor.