Tumour Markers in the Differential Diagnosis of Patients With Isolated Involuntary Weight Loss.

BACKGROUND/AIM: Paraneoplastic syndrome symptoms include isolated involuntary weight loss (IIWL). The differential diagnosis of cancer from other diseases may require a significant number of tests. Tumour markers (TMs) can be used for the diagnosis and stratification of patients according to cancer risk. PATIENTS AND METHODS: This study included 606 patients (48% females) seen at the rapid diagnostic unit for IIWL. We determined the levels of TMs carcinoembryonic antigen, carbohydrate antigen 19-9, soluble fragments of cytokeratin 19, carbohydrate antigen 15-3, carbohydrate antigen 125, neuron specific enolase, alpha-fetoprotein, prostatic specific antigen using the multiparametric analyser COBAS 601. Two cut-off points were established, the upper reference limit described by the manufacturer and a high cut-off point suggested by Molina et al., to stratify patients according to cancer risk. RESULTS: Patients were classified according to TM levels as follows: I) all TMs below the upper reference limit; II) highest number of TMs between the two cut-offs; III) at least one TM above the higher cut-off. The odds ratio for malignancy was 4.3 for group II and 248 for group III. These results indicate that when at least one TM is above the higher cut-off, neoplasia is highly probable. CONCLUSION: TM determination allowed to establish cancer risk in patients with IIWL.

Comparative Assessment of Two Strategies for Interpreting Tumor Markers in Ascitic Effusions.

BACKGROUND/AIM: There are two strategies for the interpretation of tumor markers (TM) in fluid effusions: i) high cut-off and ii) fluid/serum ratio (F/S) and low cut-off. The objective of this study is to compare these two strategies and to determine whether diagnostic accuracy improves by the identification of possible false positives using Adenosine deaminase (ADA), C reactive protein (CRP) and % of polymorphonuclear cells (%PN). PATIENTS AND METHODS: We studied 157 ascitic fluids, 74 of which were malignant. ADA, CRP and %PN were determined in ascitic fluid, and Carcinoembryonic antigen (CEA), Cancer antigen 72-4 (CA72-4), Cancer antigen CA19-9 and Cancer antigen 15-3 (CA15-3) in both fluid and serum. RESULTS: The strategy of high cut-off showed 59.5% sensitivity at 100% specificity. The F/S strategy showed 75.7% sensitivity at 95.2% specificity. Subclassifying cases with ADA, CRP and %PN negative showed 67.5% sensitivity at 100% specificity for high cut-off and for the F/S strategy was 81.7% sensitivity at 98.7% specificity. CONCLUSION: The strategy of F/S with negative ADA, CRP and %PN allow the best interpretation for TM in the ascitic fluid.

Determination of the biological variation of S100ß and lactate dehydrogenase in disease-free patients with malignant melanoma.

BACKGROUND: Biological variation is important for determining analytical goals and for establishing the magnitude of change between two consecutive measurements. The aim of this study was to determine the biological variation for S100ß and lactate dehydrogenase in patients diagnosed with malignant melanoma but without evidence of disease recurrence. METHODS: The biological variation of S100ß and lactate dehydrogenase was estimated from a mean of four consecutive measurements in 32 patients diagnosed with malignant melanoma but without evidence of disease recurrence, 3 months after tumor resection or 4 months after finishing adjuvant treatment. The mean sampling interval was 3 months. RESULTS: Mean concentrations of S100ß and lactate dehydrogenase were 0.0557 µg/L and 6.3 µkat/L, respectively. Between-run analytical variation was 3.5% at 0.181 µg/L for S100ß and 3.5% at 2.83 µkat/L for lactate dehydrogenase. Biological variations obtained for S100ß and lactate dehydrogenase were 14.2% and 8.2%, respectively. The analytical goals (defined as 50% of biological variation) were 7.1% for S100ß and 4.1% for lactate dehydrogenase. CONCLUSIONS: The estimation of biological variation allows us to calculate analytical goals and reference change values. These are necessary tools for the correct interpretation of serial measurements in patient follow-up.

Determination of biological variation of α-fetoprotein and choriogonadotropin (ß chain) in disease-free patients with testicular cancer.

BACKGROUND: Knowledge of biological variation (BV) is important for determining analytical goals and for establishing the magnitude of change between two consecutive measurements which indicate change in a patients' health status. The aim of this work is to determine the BV for total choriogonadotropin (ß chain) (ß-hCG) and α-fetoprotein (AFP) in patients diagnosed with testicular cancer but with no evidence of recurrence of disease. METHODS: We estimated BV from a mean of five consecutive measurements in 28 patients diagnosed with testicular cancer, 3 months after tumor resection or 4 months after complete treatment with chemotherapy. The mean sampling interval was 3 months. RESULTS: The mean concentrations of α-fetoprotein and choriogonadotropin (ß chain) were 3.9 µg/L and 0.79 IU/L, respectively. Between-run analytical variation was 7.1% at 4.1 µg/L for α-fetoprotein, and 19% at 0.65 IU/L for choriogonadotropin (ß chain). BV obtained for α-fetoprotein and choriogonadotropin (ß chain) was 12.4% and 16.7%, respectively, and the reference change value (RCV) for one-tail showed 38.2% and 60.7% for α-fetoprotein and choriogonadotropin (ß chain), respectively. CONCLUSIONS: The estimation of BV allows us to calculate analytical goals and RCVs, necessary tools for the correct interpretation of serial measurements in the follow-up of patients.