Positive predictive value of breast fine needle aspiration cytology (FNAC) in combination with clinical and imaging findings: a series of 2334 subjects with abnormal cytology.

We calculate the positive predictive value (PPV) of abnormal (C3-5) FNAC, alone and in combination with clinical and imaging findings, based on a consecutive series of 2,334 subjects. The PPV of a C3, C4 or C5 report is 55.0%, 95.9% and 99.4%, respectively. C5 Cytology is highly predictive of malignancy (PPV=99.4-99.7%) except where imaging is negative or benign. When C4 cytology is associated with suspicious findings on imaging and/or palpation, its PPV increases to 98.5-98.7%. C3 is the least predictive of malignancy and even when associated with suspicious findings on imaging and/or palpation its PPV is 83.3% - C3 FNAC should therefore prompt pre-operative core biopsy. These data indicate that FNAB is still a useful test in breast diagnosis, and it may assist clinical decision-making as far as whether patients should progress to surgical management or should have further core biopsy before planning surgery.