Background Human epididymis protein 4 (HE4) measurements in serum have been proposed for improving the specificity of laboratory identification of ovarian cancer (OC). Objective To critically revise the available literature on the comparison between the diagnostic accuracy of HE4 and carbohydrate antigen 125 (CA-125) to confirm the additional clinical value of HE4. Methods A literature search was undertaken on electronic databases and references from retrieved articles; articles were analysed according to predefined criteria. Meta-analyses for HE4 and CA-125 biomarkers with OR, diagnostic sensitivity, specificity, positive (LR+) and negative (LR–) likelihood ratios as effect sizes were performed. Results 16 articles were originally included in meta-analyses, but two for HE4 and one for CA-125 were eliminated as outliers. Furthermore, for HE4 a publication bias was detected. ORs for both HE4 (37.2, 95% CI 19.0 to 72.7, adjusted for publication bias) and CA-125 (15.4, 95% CI 10.4 to 22.8) were significant, although in a heterogeneous set of studies (p<0.0001). By combining sensitivity and specificity, the overall LR+ and LR– were 13.0 (95% CI 8.2 to 20.7) and 0.23 (95% CI 0.19 to 0.28) for HE4 and 4.2 (95% CI 3.1 to 5.6) and 0.27 (95% CI 0.23 to 0.31) for CA-125, respectively. Conclusions HE4 measurement seems to be superior to CA-125 in terms of diagnostic performance for identification of OC in women with suspected gynaecological disease. Due to the high prevalence of OC in post-menopausal women and the need for data focused on early tumour stages, more studies tailored on these specific subsets are needed.

Background: Measurement of α-fetoprotein (AFP) concentrations in the serum of infants is useful for the management of testicular germ cell tumors, hepatoblastoma and hepatocellular carcinoma. Here, we provide a critical review of the available information about pediatric reference intervals (RI), focusing on their utility in interpreting AFP as an aid for cancer diagnosis. Content: Evidence sources in the available literature were critically appraised. Out of 3873 retrieved papers, 24 were finally selected and carefully inspected, and six of them overcame exclusion criteria (i.e. methodological limitations in the study design, statistical gaps, drawbacks in traceability of the AFP assay to higher order materials and/or biased reporting of AFP results). Preterm and term infants up to the 3rd month of life exhibited the highest average AFP concentrations, but the attempt of defining RI by data pooling and partitioning for age intervals was impeded by the wide variability of data. The inability of defining robust RI in the first months of life made difficult, if not impossible, using upper reference limits for ruling out malignancies with a single AFP result. Evaluating the behavior of AFP concentrations 5 days from the baseline result, if this exceeds risk thresholds partitioned for age, according to the formula X_t=X₀*2^−t/HL (where: t=days elapsed for AFP retest; HL=AFP half-life according to age; X₀=AFP baseline concentration, and X_t=predicted AFP concentration at day 5), could give a better information. Summary: Novel studies defining AFP RI in infants based on robust methodology are warranted to improve the interpretation of AFP results in pediatric oncology. In the meantime, algorithms based on both serum AFP absolute concentrations and HL may aid in cancer diagnosis.

Serum ferritin is used for diagnosing iron-related disorders. However, most studies validating this application were performed before the introduction of the 2nd and 3rd WHO International Standards (ISs) to harmonize assay results. We revised the available literature to evaluate if consolidated clinical applications of ferritin and recommended cut-offs have been validated using ISs calibrated assays. All Medline retrieved reviews and individual studies performed since ISs availability were selected and analyzed according to predefined criteria. Concerning ferritin and iron deficiency (ID), only one review, including studies published before 1988, met established criteria. Results showed that ferritin can effectively rule out ID anemia in patients with or without inflammatory disease at cut-offs of 70 and 40 μg/L, respectively. From two studies using ISs calibrated assays that met inclusion criteria, no information emerged on which cut-off should be employed to obtain similar sensitivity. Regarding iron overload, even when the framework was restricted to hereditary hemochromatosis, no synthesis of scientific evidence, if any, about diagnostic accuracy of ferritin was available both before and after ISs introduction. Available evidence of the ferritin diagnostic effectiveness is limited to ID conditions. Recommended cut-offs for this application are, however, based on studies published from 1970 to the 1980s using non-harmonized assays.

Background: In laboratory setting evaluating the agreement between two measurement methods is a very frequent practice. Unfortunately, the guidelines to refer to are not free from criticisms from a statistical methodological point of view. We reviewed the Clinical and Laboratory Standards Institute guideline EP09c, 3rd ed. pointing out some drawbacks and some aspects that have not been well defined, leaving situations of uncertainty and/or of excessive subjectivity in the judgement. Content: We have stressed the need of having replicates to estimate the systematic and the proportional biases of the measurement methods to be compared. Indeed, unequal variance of the two measurement methods gives a slope and intercept of the regression between the difference and the mean of the two values of the measurement methods to be compared that can be absolutely calculated from their means, their variances and their correlation coefficient. So, it is not possible to disentangle true from spurious biases. For laboratory professionals we have developed a worked exemplification of an agreement assessment. Summary: We have stressed the need of other approaches than the classic Bland and Altman method to calculate the systematic and proportional biases of two measurement methods compared for their agreement in a study with replicates.