Those patches are worth checking. In my husband's case, his dentist noticed a white patch on his tongue that hadn't been there when he had his previous checkup. It was biopsied almost immediately by an oral surgeon -- that report (by a lab that does only oral pathology) showed moderate dysplasia, but warned of a "skip effect," meaning that cancer cells could be hiding in areas not caught up in the biopsy.
A month later an excisional biopsy of the whole thing by an ENT showed SCC in situ, with a tiny bit superficially invasive. After SCC was found he was seen by an OC specialist at Johns Hopkins (who had access to all the previous doctor/lab reports, and we sent slides to the Hopkins lab for confirmation) and was told no further treatment was required at that time.
He's now two years out and is checked regularly by the ENT at Hopkins, the local ENT who did the second biopsy and his dentist, who uses a VELScope. All clear so far.
-- Leslie