I'm not a Doc, and your ENT is right that it isn't so until the biopsy results say so, but I take the MRI results to be a strong indicator of cancer.
If that becomes so, I highly recommend that you get immediately to one of the Cancer Centers for a full set of recommendations from a team of cancer specialists who deal with hundreds of oral cancers each year, even if just for a second opinion as to your treatment. If you only take one thing away from this Forum, getting to a Cancer Center is it!
Instead of just your ENT deciding what's best, you get a Tumor Board consisting of expert radiation, surgery, chemo and dental folks coming up with a plan to both effectively deal with the problem (surgery and/or radiation and/or chemo), but also to minimize the after-affects that may mess up your future life.
Here's the list from this site:
http://www.oralcancerfoundation.org/resources/cancer_centers.htm Then do a lot! of reading from this site and the Forum, because in the long run, the person who needs to be sheparding your case is YOU and the more you know beforehand, the better you can guide the results.
Good luck with all this and don't let it get to you -- There's plenty of help and support right here on this site,
Pete
PS: See this thread for some definitions of terms used on this Forum:
http://www.oralcancerfoundation.org/ubb/ultimatebb.php?/ubb/get_topic/f/1/t/001109.html PPS: Be sure to have someone with you whenever you are seeing the ENT or anyone else involved with your treatment -- I can tell you from experience that you will not be likely to hear everything they will be telling you...