Relation between carcinoembryonic antigen (CEA) production in colorectal cancer (CRC) tissue and serum CEA levels: Comparison between the time of recurrence and initial diagnosis.

Abstract

561 Background: Because serum CEA often becomes positive before the diagnosis of recurrence, CEA is widely used for postoperative surveillance. Serum CEA is negative at initial diagnosis as well as at recurrence in some patients. We examined the relation between serum CEA levels and tissue CEA staining status both at initial surgery and at recurrence. Methods: Between 1998 to 2012, 1,306 patients (pts) with colon cancer (CC) underwent curative resection. Serum CEA levels were measured at initial surgery and at recurrence and immunohistochemical staining for CEA in primary and metastatic lesions was performed in 46 pts. Serum CEA levels of 10ng/mL or more were regarded as positive. Results: Serum CEA were positive in 17 pts (37%) at initial surgery and in 20 (43%) at recurrence. CEA staining was positive in primary lesions in 24 pts (52%) and metastatic lesions in 33 (72%). The positive rate was higher in metastatic lesions (p=0.053). Among pts in whom serum CEA was positive at initial surgery, CEA staining in primary lesion was positive in 12 pts (71%) and negative in 5 (29%). Among pts in whom serum CEA was negative, CEA staining in primary lesion was positive in 12 pts (41%) and negative in 17 (59%). Serum CEA at initial surgery was not related to CEA staining in primary lesion(p=0.0722). Among pts positive for serum CEA at recurrence, CEA staining in metastatic lesions was positive in 19 pts(95%) and negative in 1(5%). Among pts negative for CEA at recurrence, CEA staining in metastatic lesions was positive in 14 pts (54%) and negative in 12 (46%). Serum CEA at recurrence was significantly related to CEA staining in metastatic lesions (p=0.0026). Among 33 pts in whom CEA staining was positive at recurrence, serum CEA was negative in 14 (42%). Conclusions: In pts with recurrence of CC, there was no relation between the staining CEA status and serum CEA level at initial diagnosis. In contrast, these variables were significantly related at recurrence. However, 42% of pts with positive staining for CEA in metastatic lesions had negative serum CEA levels. Our findings suggest that factors besides the production of CEA by cancer cells are related to serum CEA levels.