A small black dot appeared on the tongue. Could it be cancer?

The appearance of black spots on the tongue is not necessarily cancer. It may be caused by improper oral hygiene and food residue, possibly caused by glossitis, or induced by congestion in the body; you should develop the habit of brushing your teeth in the morning and evening, and use mouthwash after meals. You need to go to the stomatology department of the hospital for treatment.