Tumour shrinkage question

Hi all

I know the answers will be variable for this but wanted to hear what happened to your tumours If you had chemo pre surgery.
My mum has had her third chemo (FEC-T) just under two weeks ago. Her first session seemed to reduce her tumour quite a lot. She had 100% FEC but then had to have reduced 80%FEC from then on due to infection. Her second session seemed to reduce it some more but maybe not as much. This was all her own opinion. The tumour was then crudely measured and registrar agreed it had shrunk since inital measurement. However it is not know whether this is due to first and second session or just the first alone. I’m concerned that the reduced chemo isn’t work effectively. Since her third session almost two weeks ago, my mum ‘thinks’ it may be a little smaller. She goes onto T next.
I wondered what any of you had experienced. Did the tumour shrink more dramatically at first then not so much for following sessions or was it steady throughout?

Thanks.