I noticed I forgot to answer your questions:
Does it mean I had IDC 50% in situ, or not?
Your tumour was about 50% invasive and 50% in situ, meaning it wasn't spreading into surrounding tissue.
Was the cancer confined to the tumour or beginning to spread to surrounding breast tissue?
The invasive component was spreading into surrounding breast tissue.
How do they know there is no vascular invasion if it was spreading?
In the vascular system they inspected, they didn't find any tumour cells.
A lot of this is explained very well on
www.breastcancer.org
Jacqueline