In invasive ductal carcinoma the cancer starts in the ducts then spreads out. Therefore does that mean the cancer is still in the ducts in addition to the surrounding areas?

Recently my mother-in-law was diagnosed with this and sent for all the normal pre-operative and treatment tests.  In her MRI it showed the ducts were swollen but the Radiologist said she didn't see any sign of cancer.  This conflicts with what the Radiation Oncologist has told us in that her cancer started in the ducts then spread out, which we interpreted as meaning her cancer was in the ducts and now the surrounding tissues.

Oddly enough during the MRI the Radiologist read it and made diagnosis to my mother-in-laws collective system in her kidneys and not her breast.  On a second look is when the Radiologist said there was no cancer in the ducts and referred her to see a urologist.  To me this seems as though the Radiologist had a mixup in patients although she did go back and re-examine the MRI stating there was no sign of cancer in the ducts how could that be if that is where the cancer started?