Hi there aprilann, welcome to the forum.
It shouldn't corrupt your game. It works on any platform - so for instance, I had all Expansions that had been released installed when I updated, and there were people missing one or two, and then people in your situation, with just the base game. Of course, there were some glitches for some people, but the main issue was regarding a missing file in a patch, forcing everybody to use a 1GB download to patch.
I'd just download the patch, if I were you.
If there were too many glitches rendering the game unplayable, EA would've released Patch 1.52 (or whatever is next) already. And anyway, TS3 doesn't take
too long to install on it's own (or so I remember), so if you do luck out and have to reinstall, it won't be as bad.