Dear Elle53: Your question is a good one but the answer at this point is not known. It is not easy to get to the intramammary nodes so it has not been the practice to do this sort of assessment. The presence of positive lymph nodes does influence the decision to do chemotherapy but so does the size of the tumor, histology, and HER 2 status. If you were going to have chemotherapy, then you are probably as safe as you can be. If not, then you should discuss your concerns with your oncologist.
I have had chemo (4 A/C) so I will consider myself "safe."
I wrote a letter to the department in the hospital that did my radioactive trace for the sentinel node biopsy. I asked if they would have mentioned in their report an internal node if they saw one since the surgeon wouldn't be going for it anyway. I got a call from the doctor in charge and she said she reviewed my films and no internal mammary nodes showed up. However, she qualified that because the injection of the radioactive stuff was so close to the area of the internal nodes, she couldn't be sure that one wasn't obscured. So I felt a little better, but that has always been a concern of mine.
Since you had chemo, it sounds like you are protected either way.
Elle53