Your Doctor is the best to advise you of stage.
T is the size N is the lymph node involvement and M is the Metastases
What will the stage of oral cancer if it has T4aN0M0?
In lay terms, stage IV typically signifies that the cancer has moved beyond an origin. In my own case, when diagnosed in August of 2005, the cancer was in both my tongue and in lymph nodes in my neck. I had surgery to remove the cancer followed by chemotherapy and radiation therapy to 'slay the strays' . As has been indicated, your best source for answers is a trusted doctor. If you do not have one, get one. In the meantime, I am cancer-free, proof that this is not necessarily a death sentence. Hope and Humor!