G-CSF induces elevation of circulating CA 15-3 in breast carcinoma patients treated in an adjuvant setting

These data provide strong evidence that G-CSF administration can induce elevation of CA 15-3 and indicate that false-positive results should be considered when evaluating CA 15-3 in patients who are receiving G-CSF. It is speculated that this phenomenon occurs through the induction of MUC1 antigen of unknown origin by G-CSF. Experimental investigation of this clinical observation is warranted.