Have you seen your general physician yet? That might be a good first place to start since there may be another reason for the mass rather than cancer.

Your general practitioner will initiate tests that would give some direction as to what specialist to whom you would need a referral.

That being said, if and when you need an oncologist, your best option for cancer treatment is a National Cancer Institute approved Comprehensive Cancer Center. However, your choice may depend upon your insurance coverage. At the very least, you can arrange to have a second opinion (which I can't stress enough the importance of a second opinion) conducted at a CCC. That way, you can make sure you are getting an accurate diagnosis and appropriate care.

There is a list of CCC's on this website. You are lucky to live in California--there are many from which to choose. Personally, I recommend City of Hope in Los Angeles--it is a CCC--and it only handles cancer. My signature, below, summarizes why I recommend City of Hope. That's where my ex-husband had his 2nd opinion. The folks at City of Hope spared him a good portion of treatment by determining he was misdiagnosed as having cancer when he actually had a benign condition. UCLA is excellent, as well.

If you choose to by-pass the GP and go directly to an oncologist, then I suggest you start at a CCC. I assume they will take it from there with diagnostic scans, tests, etc. If not, they will bump you back to your GP.

Yes, suspecting you have oral cancer is frightening. But, please, try to stay calm. Try not to think of the worst case scenario. Even if something shows up on a scan, it doesn't necessarily mean you have cancer. Only a read on a biopsy of a tissue sample can tell for certain that it is or isn't cancer.

Take care and I hope it turns out to be nothing.