22 yrs old. I started having difficulty swallowing & for years couldn't figure out why then found out it was acid reflux&took nexium (esomeprazole). Cancer worrisom?

No worries. Cancer can develop in an area of acid reflux if you do not control the acidity well. So using Nexium (esomeprazole) type of antacids should prevent that from happening .Even when it does happen, it takes more than 20 to 30 years, so you do not need to be thinking/worrying about cancer at your young age of 22.