Breast cancer

Hello

I have a student she is around her fiftys and had breast, lung, and bone cancer. She was operated for the breast cancer and got chemo therapy for the rest.
Also she had lung punctations for 17 Times.
Now she has loads of dificulties with her breathing (getting not enough air).
She is free of this treatments since 2007 now, and is getting into Yoga.
I would be thankfull for any Tips and tricks, dos and donts in this case
to be able to suport her the best as possible.
Also she is looking for support for her breathing through Pranayama.

All the best
Lars