@cheriels I have been following your story, since it is similar to mine. I also recently had a total hysterectomy-BSO for a Stage 1, Grade 3 endometrial cancer. My sentinel lymph nodes were also negative, but I had significant myometrial invasion (10mm of 12mm) and low levels of lymphovascular invasion ("LVSI"). This makes it a "high-risk" cancer. Do you know about the extent of myometrial invasion and LVSI in yours?

I saw three different local doctors (no Mayo clinic) who recommended three different treatments (1: chemo + vaginal brachytherapy, 2: pelvic radiation, 3: chemo + pelvic radiation). I'm currently going for choice 1, and had my first round of chemo yesterday. I have an office visit with the radiation oncologist in a couple weeks.

The purpose of the follow-up treatment is to try to kill any cancer cells that may have escaped the primary tumor and are currently lurking somewhere, most likely in the vagina or in pelvic lymph nodes, but that haven't formed a tumor that's large enough to see yet on a PET-CT. Higher grade tumors are more likely to do that, and these stray cells can grow into tumors later.

I don't know if you want to cause trouble with your care team like I did with mine, but I'm happy that I insisted on having my tumor tested for mutations in the POLE gene. These are present in 10-20% of Grade 3 endometrial tumors, and tumors with this mutation have a MUCH better prognosis. In fact, the European treatment guidelines that went into effect almost 2 years ago categorize all POLE mutant tumors as "low risk" and recommend only observation as treatment. Of course no American doctor would recommend that, and POLE mutation testing is currently not "standard of care" in the US. I didn't try getting it covered by insurance, but it probably would have been a lost cause. However it was $450 at Stanford, and it definitely made me $450 happier, even though my result was negative (the bad result). I would have been really happy if it had been positive.