Hello. Thanks for posting your query here.
Let me give some brief introduction about adenoids. Adenoids are lymphyocytic aggregates at the back of nose and at the junction of nose and throat. They are protective structures that aid in protection from viral and bacterial infections. Adenoids get enlarged when there is an infection or inflammation. Repeated attacks of common cold, even can stimulate the adenoids and result in their enlargement.
Adenoids can result in obstruction during respiration when they get enlarged. The diagnosis of adenoids is usually done by physical examination, and some imaging techniques. If it were to be a naso pharyngeal carcinoma, there would be other symptoms like weight loss, repeated attacks of infections, and it can be easily identified by physical examination and imaging techniques. I suggest you not to get worried and I recommend you to follow the precautions that are advised by your physician.
Hope this helps.