<prompt> Which of the following test is unable to differentiate between in situ breast cancer and invasive disease:Core needle biopsyFNACExcisional biopsyNone  <response>: FNAC is the least invasive technique for obtaining a cell diagnosis and is very accurate if both operator and cytologists are experienced.However false negatives do occur, mainly through sampling error, and invasive cancer cannot be distinguished from in situ disease.A histological specimen taken by core biopsy allows a definitive preoperative diagnosis, differentiates between duct carcinoma in situ DCIS and invasive disease and also allows the tumor to be stained for receptor status.This is important before commencing neoadjuvant therapy. Bailey and Love 