Hi
This is not cancer.. This is not a big issue so don’t worry. Kindly get your tooth treated because this is going to cause you big trouble for instance pain while eating, sensitivity to spicy food, inflammation etc.
Next Steps
Get your tooth treated, if it is sharp get enameloplasty done i.e. get it blunt so that it doesn’t irritate you.
Health Tips
Till the time you visit a dentist, apply some topical medicine like gel or mouthwash. Apart from that do warm saline rinses