Oops! I meant to post this link about staging - http://www.cancer.org/cancer/endometrialcancer/detailedguide/endometrial-uterine-cancer-staging
I understand your fears. Hysterectomy is major surgery and the surgical risks are quite a bit higher in someone your age, healthy or not.
Was this cancer diagnosed from an endometrial biopsy or D&C? Were imaging tests (such as MRI, CT scan) done to see if it has spread? Have you seen these reports? There are two systems of staging endometrial cancer. One system has a T0 stage (the other does not) which is considered a pre-cancerous condition which may be curable with medication such as Megestrol. Unfortunately, hysterectomy is grossly overused with only 2% done for a cancer diagnosis. So it is important that we advocate for ourselves which includes getting an accurate diagnosis and understanding the implications of that diagnosis as well as all treatment options and their risks and benefits. Also, keep in mind that pathologists have different levels of expertise just as doctors do. So getting a pathology second opinion (as well as a doctor second opinion) may be worthwhile.
I had an unwarranted hysterectomy and oophorectomy for possible ovarian cancer. Despite the ovarian cyst being benign (as determined by frozen section while I was in the operating room), my gyn removed all my sex organs anyway. My health quickly deteriorated. Getting my medical records was eye-opening as I discovered unethical tactics by both my gynecologist of 20 years as well as the oncologist. I wish I had done things very differently but I had never had to navigate the medical "maze" before all this happened. And of course, the fear of ovarian cancer clouded my thinking.
So, you are saying that you would live with the uterine cancer because you are afraid you will not survive anesthesia? What does your doctor say about this concern? It is pretty rare to not survive anesthesia, but it is pretty serious to ignore cancer. If they think they can excise the cancer completely with surgery, you then have to talk about the odds. If it's 100% getting over the cancer versus 1% dying from the anesthesia, I know what I would choose. You may be 85 but you are not 105, you could have many more years even yet. But not if you knowingly do nothing about cancer.