PLASMA SIALIC-ACID AS A MARKER OF THE EFFECT OF THE TREATMENT ON METASTATIC COLORECTAL-CANCER

The concentration of total sialic acid (TSA) is increased in the plasm a of patients with many types of cancer. The purpose of this study was to assess the usefulness of the TSA marker in predicting the efficacy of the treatment, and to compare TSA with two common markers, carcino embryonic antigen (CEA) and the carbohydrate antigen 19-9 (CA 19-9). T he study was performed on 44 patients treated for advanced colorectal carcinoma by a weekly 8h continuous infusion of 5-fluorouracil (1300 m g/m(2)) plus bolus injection of L-folinic acid (100 mg/m(2)). TSA, CEA and CA 19-9 levels were measured before and after 3 months of treatme nt and their variations analysed as a function of the response to the treatment. TSA levels of patients with metastatic colorectal carcinoma before treatment (959 +/- 265 mg/l) were significantly higher than th ose of 32 healthy people (584 +/- 99 mg/l). The percentage of patients with TSA concentration above the cut-off level (782 mg/l) was 73% bef ore treatment and 23% after. All patients who experienced an objective response to the treatment (complete, partial or minor response) (n=29 ) had a significant decrease of TSA levels (t = 5.96; P < 0.001). When the disease was considered as stabilised (n=10), TSA changed slightly , but it increased with progressive disease (4 out of 5 patients). Cha nges in CEA and CA 19-9 did not correlate as web as TSA to the treatme nt efficacy. Initial levels of TSA did not permit prediction of the ef ficacy of the treatment since they were not significantly different be tween the five response groups. TSA seems to be more likely involved i n tumour changes than in tumour volume. Its determination could provid e useful information about the spreading and metastatic properties of the tumour. TSA normalisation is an indicator of probable tumour growt h arrest and its elevation could be a marker of relapse. (C) 1997 Else vier Science Ltd.