Serum carcinoembryonic antigen and acute phase reactant proteins in the pre-operative detection of fixation of colorectal tumours.

Fixity of colorectal tumours carries a poor prognosis, but only if it is the consequence of malignant spread. Pre-operative radiotherapy may be beneficial but selection depends on clinical examination which is often inaccurate or impossible. We therefore investigated if serum concentrations of carcinoembryonic antigen and acute phase reactant proteins (APRPS) which may be elevated in patients with colorectal cancer could determine the degree and nature of local spread prior to operation. Carcinoembryonic antigen (CEA), alpha 1 acid glycoprotein (AGP) and C-reactive protein (CRP) were measured pre-operatively in 100 patients with colorectal tumours, 89 of whom had a carcinoma. Thirty-two (36 per cent) were fixed, 18 (56 per cent) by malignancy (FM) and 14 (44 per cent) by inflammation (FI). Levels of CEA, AGP and CRP were all significantly higher in the serum of patients with fixed tumours (P less than 0.05). Concentrations of AGP greater than 1.4 g/l or CRP greater than 15 mg/l were accurate predictors of tumour fixation (specificity 87 and 90 per cent; sensitivity 78 and 78 per cent. CEA appeared more accurate in determining the nature of fixation. A value of greater than 50 ng/ml predicted 82 per cent of FM tumours (specificity 100 per cent; sensitivity 87 per cent). Thus, pre-operative measurement of serum CEA and APRP appear able to predict fixation of colorectal tumours.