A confirmed diagnosis of mouth cancer is only possible after the tissue in question is removed through a biopsy and examined under a microscope for cancerous cells, according to the Oral Cancer Foundation. Steps during discovery may include X-rays or a CT scan.
A physician first performs a visual assessment of the area in question, says the Oral Cancer Foundation. After determining that the possibility of cancer exists, a qualified doctor performs a biopsy, a procedure in which a section of the lesion is removed through an incision or extracted with a needle. A pathologist then examines the tissue sample to determine if it contains malignant cells. An X-ray, CT Scan or MRI may also be performed to assess the extent of the cancer's growth.