A case of serum CEA disappearance curve after resection of breast carcinoma.

Carcinoembryonic antigen (CEA) elimination kinetics after tumor resection were measured in a case of breast cancer. A 45-year-old woman with a left breast carcinoma underwent surgery after neoadjuvant chemotherapy. The serum CEA level before surgery was 34.3 ng/ml. After sequential monitoring of serum CEA levels, postoperative serum CEA elimination kinetics were calculated using non-linear least square analysis with the fitting equation C(t)=(C0-Cp)exp(-kt)+Cp, where C(t) was the postoperative CEA level, t was the number days after surgery, C0 was the CEA level at postoperative time zero, Cp was the CEA at plateau, and k was the rate constant of elimination. Cp was calculated as 6.9 ng/ml, which was above the cut-off level and indicated residual malignancy. After adjuvant chemotherapy, CEA normalized to 1.8 ng/ml. In breast cancer patients with high preoperative serum CEA levels, our analytical method for CEA elimination might be useful for the detection of residual malignancies.