Cancer in my Golden Retriever

My 8-year old Golden, Maggie, had a growth removed from her thyroid last week.  I took her back to the vet today for a re-check and found out that the growth was cancerous.  However, it appears it was well-encapsulated and didn’t invade the tissues around the thyroid, so that is good news.  The vet said it’s still possible that the tumor metastasized before it was removed, but for now, it looks like she is in good shape.