Tumour markers in the detection of opisthorchiasis-associated cholangiocarcinoma

Opisthorchiasis is a major public health problem in north-east Thailand, where over 7 million inhabitants are reported to be infected. A significant percentage of infected individuals develops cholangiocarcinoma terminally, which is rapidly fatal. To determine whether certain tumour markers are elevated in Thai patients with cholangiocarcinoma, and thus might be useful in the diagnosis of cholangiocarcinoma associated with opisthorchiasis in Thailand, the tumour markers CA125 and CA19-9 were measured by radioimmunoassay in 94 serum samples. The subjects consisted of 52 patients admitted for non-gastroenterological diseases, 7 patients with histologically proven cholangiocarcinoma, 7 patients with clinically suspected cholangiocarcinoma, and 28 patients with uncomplicated opisthorchiasis. The mean levels (±standard deviation [SD]) of CA19-9 and CA125 in the controls were 12·5 ± 10·2 and 24·7 ± 11·1 units/ml respectively. Using the mean + 3SD as the cut-off level, 57·1% of patients with confirmed cholangiocarcinoma had elevated CA19-9 and 28·6% had elevated CA125. In patients with clinically suspected cholangiocarcinoma, 71·4% had elevated CA19-9 and 28·6% had elevated CA125. Among opisthorchiasis patients, 3·6% had elevated CA125 and none had elevated CA19-9. 1·9% of controls had elevated CA19-9 and none had elevated CA125. When positivity of either CA125 or CA19-9 was used as an indicator of malignancy, the sensitivity and specificity of the combined tests reached 85·7% and 98·1% respectively. These preliminary results suggest that the measurement of CA125 and CA19-9 may be useful in the early detection of opisthorchiasis-associated cholangiocarcinoma.