The clinical significance of the pattern of elevated serum carcinoembryonic antigen (CEA) levels in recurrent colorectal cancer.

Serial serum carcinoembryonic antigen (CEA) assays were performed in 148 patients after potentially curative surgery for colorectal cancer. Thirty-seven patients developed proved recurrent tumour in a follow-up period of 2-5 years. Elevated CEA levels were recorded in 36 of these patients and in 27 rising levels preceded clinical symptoms of recurrent tumour. Two distinct patterns of CEA rise were observed: a 'fast' rise in which serum concentrations reached 100 microgram/l within 6 months of the first elevation and a 'slow' rise in which concentrations remained less than 75 microgram/l for at least 12 months. The majority of patients with the 'fast' rise had metastatic spread, whereas most patients with a 'slow' rise had local recurrence alone. This differential pattern may help to predict the site of recurrent tumour.