If you are worried about cancer, it would be advisable to show it to doctor to reduce your anxiety. It will be just a precaution. There can be number of reasons tor swelling,Only doctor can say about the cause of swelling.Or it may just be ordinary reason. and would go away after some time.If continues to grow further, you should get it examined.
This is probably not cancer but it absolutely does need to be examined by a doctor in order to give you a diagnosis and peace of mind.