A biopsy by an oral surgeon of a small bit of a leukoplakia (white patch) on my husband's mobile tongue came back with a diagnosis of moderate dysplasia (not cancer, but not normal, either) -- but by the time of an ENT's excisional biopsy a month later (hey, the first diagnosis wasn't cancer, so what's the rush?) it had turned into squamous cell carcinoma in situ with a small bit superficially invasive.

I gather that what is left on your tongue has been diagnosed as dysplasia, not cancer (as the 1-cm area already removed from your tongue was). Not all dysplasia turns to cancer -- but you've already been diagnosed with cancer once, so it's more likely than not, I'd think, that what's left could also turn to the dark side. Carcinoma in situ is cancer, and it does spread. The cancer journey of every patient here began with carcinoma in situ; in the seven years that I've been here, only a few were lucky enough to have it identified, removed and diagnosed at that stage.

If I were in your situation, I'd get what's left taken out pronto. This isn't something you want to sit on and see what happens. An appointment ASAP with a comprehensive cancer center that see a LOT of oral cancer would be prudent.