BACKGROUND Rising serum tumor markers after chemotherapy are generally considered to indicate tumor progression. However, we have observed a transient increase in carcinoembryonic antigen (CEA) or carbohydrate antigen 19-9 (CA19-9) levels despite clinical benefits from chemotherapy in patients with metastatic or recurrent gastric cancer (MRGC). Therefore, this study was performed to determine the incidence of CEA and CA19-9 surges and their implications on the clinical outcome in MRGC patients.

MATERIAL AND METHODS Fifty-one and 40 patients who had evaluable data for CEA or CA19-9 surges, respectively, were included. Both CEA and CA 19-9 surges were defined as a > 20% increase in these tumor markers from the baseline that was followed by a > 20% drop in subsequent levels compared to the baseline.

RESULTS Of 51 evaluable patients for CEA surges, nine patients (18%) had documented CEA surges. The median time to CEA peak and the duration of the CEA surge were 2.8 (1.7 approximately 7.0) and 9.1 weeks (7.6 approximately 21.0), respectively. Of 40 evaluable patients for CA19-9 surges, seven patients (18%) had CA19-9 surges. The median time to peak and the duration of the CA19-9 surge were 2.3 (1.9 approximately 6.0) and 7.1 weeks (4.3 approximately 16.1), respectively. All patients with CEA or CA19-9 surges had radiographic evidence of benefits from chemotherapy.

CONCLUSION CEA or CA19-9 surges can be observed in MRGC patients receiving chemotherapy. All patients with these surge phenomena had clinical benefits from chemotherapy. An initial rise in CEA or CA19-9 levels after initiation of chemotherapy should not be used as an indicator of progressive disease.