http://www.oralcancerfoundation.org/search.htm to the search engine. Enter clinical trials. You will find the resource page links to clinical trial search engines.
Remember for the most part clinical trials are hard to qualify for, let alone find one that you want to be part of near you. It is all about exluding people that do not meet the matching criteria of the trial. Most trials are very limited in the parameters of the participating patients.