Abstracts
1998 Digestive Disease Week

#1000

CEA IS USEFUL TO DETERMINE THE NEED FOR A PREOPERATIVE CT SCAN IN PATIENTS WITH COLORECTAL CANCER. S Kelly, MA Malangoni, Case Western Reserve University, Dept. of Surgery, MetroHealth Medical Center, Cleveland, Ohio.

Objective: To determine the utility of preoperative serum carcinoembryonic antigen (CEA) determination to predict the presence or absence of hepatic and lymphatic metastasis. Methods: Retrospective review of patients with colorectal cancer treated between 1985-1993. Results: 213 patients were evaluated. 110 patients had a preoperative abdominal CT scan and 149 had a CEA done before operation. The pathologic stage was used as the standard for comparison. The distribution of tumor stage (modified Dukes' class) was: CIS, 4 pts.; A, 18 pts.: B, 93 pts.; C, 52 pts.; and D, 39 pts.. The incidence of hepatic metastasis was slightly, but not significantly, higher in patients who had a preoperative CT scan (25.4% vs. 10.7% in unscanned patients); however, the incidence of lymphatic metastasis was similar in scanned (21.8%) and unscanned (27.2%) patients. The threshold of a CEA < 5 had a sensitivity of 84.6%, a specificity of 52.2% and correctly predicted the absence of hepatic metastasis in 93.8% of patients. The use of CEA _ 15 had a sensitivity of 69.2%, a specificity of 83.5% and a positive predictive value of 48.7% for hepatic metastasis. In contrast, CEA < 5 had a lower negative predictive value (70.8%) while CEA _ 15 had a similar positive predictive value (47.6%) for determining the presence of lymphatic metastases. Of the 13 patients who had their operative plan changed based on the CT scan (additional service involvement, change to palliative procedure), only two had a CEA < 5. Conclusions: Preoperative CEA is useful to determine which patients with colorectal cancer may benefit from a preoperative CT scan. CEA < 5 is a highly accurate predictor of the absence of hepatic metastasis and other abnormalities on CT scan that affect operative strategy. Eliminating the CT scan in these patients can save costs (approximately ,400/patient). A CEA > 15 is associated with a high incidence of hepatic metastasis and should prompt a preoperative CT scan. CEA values between 5 and 15 are indeterminate and require further study.

Copyright 1996 - 1998, SSAT, Inc. Revised 29 June 1998.