Background and objective: An increase in carcinoembryonic antigen (CEA) and/or carbohydrate antigen 19-9 (CA19-9) levels is generally considered as tumor progression in patients with metastatic colorectal cancer (MCRC). However, a transient CEA surge has been observed in patients with MCRC responding to chemotherapy. This study was to investigate the clinical significance of transient CEA/CA19-9 surges in Chinese MCRC patients.
Methods: One hundred and twenty-one MCRC patients with histologically proven adenocarcinoma and baseline ECOG performance status of < or =2 were treated with oxaplatin and (or) irinotecan-based chemotherapy regimens. Serum CEA and CA 19-9 levels were measured before and after chemotherapy.
Results: Of the 121 patients, 14 (11.6%) had transient CEA surges with median baseline CEA level of 45 microg/L (9.67-2208 microg/L) and median surge peak level of 80.1 microg/L (13.38-4044 microg/L). The transient CEA surge occurred at a median of 4 weeks (2-6 weeks), and lasted for a medium of 6.5 weeks (4-14 weeks). Of the 14 patients, 11 received oxaplatin-based chemotherapy; three received irinotecan-based chemotherapy. All the 14 patients showed clinical benefit from chemotherapy, among which seven achieved partial response and seven had stable disease. In the meantime, five patients (3.8%) had transient CA19-9 surges. However, no significant correlation was found between an increase in the CA19-9 level and clinical benefits.
Conclusions: Transient CEA surges can be observed in Chinese MCRC patients receiving oxaplatin or irinotecan-based chemotherapy, which does not indicate tumor progression, but good therapeutic efficacy. A transient elevation of CA19-9 is not correlated to short-term clinical benefits.