I hope I am not out of line here and overstepping, but until you get biopsy results, it is easy to imagine the worst. The size of a tumor doesn't always indicate the stage it is in, even if in fact it is cancerous. In my case when they found my tumor and biopsied it, the doc said it was big and appeared advanced. He felt it was cancer and could be stage 3 or 4, but without the lab results, that assessment was based on his educated and experienced best guess. He was a gastrointestinal doc that did endoscopy and colonoscopy all day, 4 days a week. He knew cancer very well.
He told me to not stress about it, because without the lab results, it wasn't legally or medically a diagnosis of cancer. He said while the chances that it wasn't were slim, there is always that chance. It turned out to be cancer by the biopsy, but the stage could only be established l after it was removed. When it was removed and biopsied again with surrounding tissue and lymph nodes, it was stage 1 going on stage 2. No spread and no penetrating through the tissue it was growing on. He was surprised that such a large in diameter tumor was so flat.
I am sharing this in hopes both of you will try not to think the worst based on the ER doctors and others that have just read the MRI and Cat scan. Did they do the contrast imaging? That would tell more, but still not a "chiseled in rock" cancer diagnosis and certainly not evidence it is terminal. Try to enjoy the next few days, best you can, while waiting for the biopsy and results. I have no doubt an Oncologist will order a PET scan. It is imperative they study any tissue that might be effected.