@gratefulcat That's wonderful that you are three weeks post and you feel well. Also, that's very good news with Stage1a. It could be upsetting but actually helpful that you know you are at high risk for Lynch Syndrome and that you will be carefully monitored.

I had two sessions of brachytherapy when I had a recurrence of endometrial (adenocarcinoma) two years post hysterectomy. The team at Mayo Clinic helped me to feel as a relaxed as one can be in that situation and explained everything before it happened. So, no surprises which I appreciated. I did not have any pain with the procedure and felt comfortable enough to get up and walk away afterwards. I was fatigued overall from the external radiation with the two brachytherapy sessions but that was expected.

Long term side effects? It was explained to me that with external and internal radiation I needed to use a vaginal moisturizer on a regular basis and a vaginal dilator. The scar tissue from radiation can occlude the vagina and it's important to do this for one's long-term comfort and your future vaginal and pelvic exams. Hopefully, your radiation oncologist and/or the education nurse will explain all this to you.

When do you start the radiation and brachytherapy?

There is a discussion on radiation therapy here and you can read what others have shared as well as post your questions or your experiences:

What kind of radiation did you get for your gynecological cancer?

-- https://connect.mayoclinic.org/discussion/types-of-radiation-treatments-for-gynecological-cancers/