Chromogranin A (CgA) is gaining acceptance as a serum marker of neuroendocrine tumors. Its specificity in differentiating between neuroendocrine and nonneuroendocrine tumors, its sensitivity to detect small tumors, and its clinical value, compared with other neuroendocrine markers, have not clearly been defined, however. The objectives of this study were to evaluate the clinical usefulness of CgA as neuroendocrine serum marker. Serum levels of CgA, neuron-specific enolase (NSE), and the alpha-subunit of glycoprotein hormones (alpha-SU) were determined in 211 patients with neuroendocrine tumors and 180 control subjects with nonendocrine tumors. The concentrations of CgA, NSE, and alpha-SU were elevated in 50%, 43%, and 24% of patients with neuroendocrine tumors, respectively. Serum CgA was most frequently increased in subjects with gastrinomas (100%), pheochromocytomas (89%), carcinoid tumors (80%), nonfunctioning tumors of the endocrine pancreas (69%), and medullary thyroid carcinomas (50%). The highest levels were observed in subjects with carcinoid tumors. NSE was most frequently elevated in patients with small cell lung carcinoma (74%), and alpha-SU was most frequently elevated in patients with carcinoid tumors (39%). Most subjects with elevated alpha-SU levels also had elevated CgA concentrations. A significant positive relationship was demonstrated between the tumor load and serum CgA levels (P < 0.01, by chi 2 test). Elevated concentrations of CgA, NSE, and alpha-SU were present in, respectively, 7%, 35%, and 15% of control subjects. Markedly elevated serum levels of CgA, exceeding 300 micrograms/L, were observed in only 2% of control patients (n = 3) compared to 40% of patients with neuroendocrine tumors (n = 76). We conclude that CgA is the best general neuroendocrine serum marker available. It has the highest specificity for the detection of neuroendocrine tumors compared to the other neuroendocrine markers, NSE and alpha-SU. Elevated levels are strongly correlated with tumor volume; therefore, small tumors may go undetected. Although its specificity cannot compete with that of the specific hormonal secretion products of most neuroendocrine tumors, it can have useful clinical applications in subjects with neuroendocrine tumors for whom either no marker is available or the marker is inconvenient for routine clinical use.
The use of the road map based on Sigma Metrics leads to fast and easy implementation of optimal Westgard QC rules.
The Cyfra 21.1 assay is a newly developed test which measures in serum a fragment of cytokeratin 19. We evaluated this marker in 212 patients with non-small-cell lung cancer (NSCLC), predominantly stage 3a-b and 4, and compared it with three other markers: carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC) and tissue polypeptide antigen (TPA). Sensitivities for Cyfra 21.1, TPA, CEA and SCC (using cut-off levels corresponding to a 95% specificity for benign lung diseases) were 40%, 40%, 42% and 19% respectively. The sensitivity of CEA was significantly higher in patients with adenocarcinomas compared with the other three markers, while the sensitivity of Cyfra 21.1 and TPA was significantly higher in patients with squamous cell carcinomas. The value of Cyfra 21.1 for monitoring disease during chemotherapy could be evaluated in 23 patients with squamous cell carcinomas. When the cases of lead time were included a concordance between clinical evaluations according to WHO response criteria and evaluations according to changes in the marker levels of 74% was found. The criteria defined for marker response were a 65% decrease in the marker level for a partial response and a 40% increase for progressive disease. In particular, increasing levels of this marker indicated usually disease progression. In conclusion, Cyfra 21.1 is a useful serum marker for patients with NSCLC, especially for disease monitoring of patients with squamous cell carcinoma during and after chemotherapy.
The influence of interference by hemolysis, icterus and lipemia on the results of routine chemistries may lead to wrong interpretations. The H-, I- and L-indices that can be measured by the Beckman LX-20 instrument (Beckman Coulter) in serum or plasma samples are a reliable semi-quantitative measure of the size of these interferences. A survey carried out in 16 Dutch clinical laboratories on the use of these indices demonstrated that in several of these laboratories, the influence of interferences is largely underestimated. Therefore, a multicenter study was carried out in which we examined the interference of hemolysis, icterus and lipemia on 32 analytes. On the basis of biological variation, we decided on cutoff indices above which analytically significant interference exists. We found analytically significant interference by hemolysis, icterus or lipemia, in 12, 7 and 15 of the 32 analytes studied, respectively. Flagging of results on the basis of analytically significant interference, however, results in too many clinically insignificant comments. On the basis of clinical significance, we conclude that significant interference by hemolysis, icterus or lipemia is present in only 5, 6 and 12 of the analytes studied, respectively. Use of the cutoff indices presented here facilitates optimal use of the LX-20 indices to prevent reporting of wrong results due to interference.
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