I had a total thyroidectomy 15 years ago to treat thyroid cancer. I had a lumpectomy, radiation, and chemotherapy 3 years ago for breast cancer. 2 years ago I had I-131 (high dose of radiation) to treat a recurrence of my thyroid cancer. As a follow up, I had a PET scan last week. All looked normal except my doctor said my thymus gland was enlarged compared to the PET scan from the year before. She said that no follow up was needed and not to worry, but what does this mean? Has anyone else experienced this?