p does stand for Pathology. We are often given a preliminary path report after biopsy and then a final pathology after surgery. N0 means no lymph node involvement and MX doesn mean no distal metastisis. PJ was correct. The oncologist is the one who will look at your path report and tell you whether or not you should need chemo but it doesn't sound like you will. If you had a lumpectomy with Sentinal node biopsy then you will most likely need radiation. If you had a mastectomy, you may be done without further treatment.
Good luck!
Sherree