P.K.
Everyone is different. Everyone I knew who went thru breast cancer did great. I.e., teacher would leave school Friday and be back Monday. Also depends on personality. My best friend who lived with me for a year did great. She had heavy duty chemo. It was only to prolong her life and it did by 18 months. She would finish her chemo, take a short nap and we would then go on. She had a terrible cancer but an incredible sense of humor and positive outlook. In today's world, they give so many drugs before the chemo to counteract any effects. It truly is amazing. Try and keep a positive outlook and remain upbeat. She will have her moments and that is ok. If I ever told you the things we did, you would wet your pants. Lol. We dressed up as nuns and went to radiation. It was hysterical. All the nurses we knew did not know it was us! The waiting room cracked up. We bungi jumped at the mall. Rode a kids train around the mall. Had makeovers. When we went to have her head shaved, we just embraced the new Debbie. We laughed. We also knew that eventually the end would come and had our moments when we talked. Deb always did my flower boxes. She loved doing it. A week before she passed, she said "did you do the boxes yet". I told her no. I got the look, went home did them and brought back pictures.
I think your sister will do great and live a long life.
Oh forgot, when she started chemo the waiting room was a very depressing place to be. We took care of that with a laughing dog who rolled around on the floor. At first no one knew what to think. Then one person started to laugh and so it went. Before we knew it people were laughing and talking to each other. They thanked us for the laughter we brought in to them.
So do not be afraid to laugh and have some fun with her. That is the one thing we noticed people were afraid to just be themselves.
Prayers and hugs. We also tried on wedding gowns. Why. Just because. Lol.