Circulating tumor markers: a guide to their appropriate clinical use | Comparative summary of recommendations from clinical practice guidelines (PART 1)

Design, validation and performance of aspartate aminotransferase- and lactate dehydrogenase-reporting algorithms for haemolysed specimens including correction within quality specifications

BACKGROUND

In vitro haemolysis is a major operational challenge for medical laboratories. A new experimental design was used to investigate under what conditions algorithms could be designed to report either quantitative or qualitative aspartate aminotransferase and lactate dehydrogenase results outside the manufacturer's haemolysis specifications. Quantitative corrections were required to meet prespecified quality specifications.

METHODS

Twenty-five patient samples were used to design reporting algorithms and another 41 patient samples were used to validate the algorithms. Aspartate aminotransferase, lactate dehydrogenase and haemolysis index were determined using a Cobas 6000 analyser (Roche diagnostics, Mannheim, Germany). Correction factors were determined, and the accuracy of the correction was investigated. Reporting algorithms were designed based on (i) the manufacturer's cut-off for the haemolysis index, (ii) corrections within the total allowable error specification and (iii) qualitative reporting based on obtained results. The impact of the reporting algorithms was retrospectively determined by recalculating six months of aspartate aminotransferase and lactate dehydrogenase results.

RESULTS

No correction for aspartate aminotransferase/lactate dehydrogenase was possible for results below the upper reference interval limit, while results equal to or greater than the upper reference interval limit could, up to mild haemolysis, be corrected within the total error criterion. All samples generated from the validated patient cohort fulfilled the set criteria. The algorithms allowed reporting 88.5% and 85.9% of otherwise unreported aspartate aminotransferase and lactate dehydrogenase results, respectively.

CONCLUSIONS

An approach is presented that allows to generate and validate reporting algorithms for aspartate aminotransferase and lactate dehydrogenase compatible with prespecified quality specifications. The designed algorithms resulted in a significant reduction of otherwise unreported aspartate aminotransferase and lactate dehydrogenase results.

Relevance of blood tumor markers in inpatients with significant involuntary weight loss and elevated levels of inflammation biomarkers

PURPOSE

To assess the diagnostic performance of a panel of standard tumor markers (TMs) in patients hospitalized with significant involuntary weight loss (IWL) and elevated levels of inflammation biomarkers, and a combination of the TM panel and the finding of the computed tomography (CT) scan.

METHODS

We conducted a retrospective study in the internal medicine department at Amiens-Picardie University Medical Center (Amiens, France) between January 1st, 2015, and November 1st, 2021. The inclusion criteria were age 18 or over, significant IWL (≥ 5 kg over 6 months), elevated inflammation biomarkers (e.g. C-reactive protein), and assay data on two or more standard TMs (carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 19 - 9, CA 15 - 3, CA 125, neuron-specific enolase (NSE), alpha-fetoprotein (AFP), calcitonin, and prostate-specific antigen (PSA)). The result of each TM assay was interpreted qualitatively (as positive or negative), according to our central laboratory's usual thresholds.

RESULTS

Cancer was diagnosed in 50 (37.0%) of the 135 patients included. Positivity for one or more TMs had a positive predictive value (PPV) of 0.55 [0.43-0.66], and a negative predictive value (NPV) of 0.84 [0.75-0.93] for cancer diagnosis. When combined with the presence of suspicious CT findings (e.g. a mass, enlarged lymph nodes and/or effusion), positivity for one or more TMs had a PPV of 0.92 [0.08-0.30]. In the absence of suspicious CT findings, a fully negative TM panel had an NPV of 0.96 [0.89-1.00].

CONCLUSION

A negative TM panel argues against the presence of a cancer, especially in the absence of suspicious CT findings.

Are Tumor Marker Tests Applied Appropriately in Clinical Practice? A Healthcare Claims Data Analysis

Tumor markers (TM) are crucial in the monitoring of cancer treatment. However, inappropriate requests for screening reasons have a high risk of false positive and negative findings, which can lead to patient anxiety and unnecessary follow-up examinations. We aimed to assess the appropriateness of TM testing in outpatient practice in Switzerland. We conducted a retrospective cohort study based on healthcare claims data. Patients who had received at least one out of seven TM tests (CEA, CA19-9, CA125, CA15-3, CA72-4, Calcitonin, or NSE) between 2018 and 2021 were analyzed. Appropriate determinations were defined as a request with a corresponding cancer-related diagnosis or intervention. Appropriateness of TM determination by patient characteristics and prescriber specialty was estimated by using multivariate analyses. A total of 51,395 TM determinations in 36,537 patients were included. An amount of 41.6% of all TM were determined appropriately. General practitioners most often determined TM (44.3%) and had the lowest number of appropriate requests (27.8%). A strong predictor for appropriate determinations were requests by medical oncologists. A remarkable proportion of TM testing was performed inappropriately, particularly in the primary care setting. Our results suggest that a considerable proportion of the population is at risk for various harms associated with misinterpretations of TM test results.

Overordering of tumor marker for outpatients revealed by performance indicators and the impact of a health policy intervention: An observational study using administrative records

PURPOSE

The overuse of laboratory tests contributes to impair health systems effectiveness, tumor markers (TMs) being a paradigmatic example. In the present study we applied indicators of TMs appropriateness developed from administrative datasets to appraise regionwide overordering in the clinical practice.

PATIENTS AND METHODS

TMs ordered to outpatients in the Veneto Region over 6 years were obtained from the eletronic Outpatients' Records of Diagnostic and Therapeutic Procedures. TMs orders were examined as aggregated data or stratified according to disease codes, gender, age, and requests per patient. TMs recommended only for specific malignancies were examined using epidemiological data obtained from Veneto Tumor Registry.

RESULTS

A total of 5,821,251 TMs were ordered in 4,382,159 patients over 6 years. Overall, 3,252,389 (55.9%) TMs were ordered without appropriate disease codes (ranging from 77.0% for PSA to 17.5% for CA15.3). TM orders declined over 6 years (-13.4%), with a noticeable reduction of orders without appropriate disease codes (-21.3%). Orders decreased sharply from 2015 to 2016, after the enactment of a national Decree-Law aimed at improving appropriateness, and remained stable thereafter. However, the rate of inappropriate TMs requests still remained elevated (44.4%) in the last year of observation, with orders of TMs being much higher than expected on the basis of prevalence and incidence figures of specific malignancies.

CONCLUSIONS

Indicators developed from administrative datasets were effective in assessing the overordering of TMs and the impact of interventions to improve appropriateness. The developed indicators could be considered for other diagnostic tests.

Clinical usefulness of circulating tumor markers

Tumor markers are a heterogeneous group of substances released by cancer cells into bloodstream, but also expressed by healthy tissues. Thus, very small concentrations can be present in plasma and serum from healthy subjects. Cancer patients tend to show increased levels correlating with tumor bulk, but false positive results could be present in patients with benign conditions. The correct interpretation of TM results could be challenging and many factors should be considered, from pre-analytical conditions to patient concomitant diseases. In this line, the Clinical Chemistry and Laboratory Medicine journal has made important contributions though several publications promoting the adequate use of TM and therefore improving patient safety. TM measurement offers valuable information for cancer patient management in different clinical contexts, such as helping diagnosis, estimating prognosis, facilitating early detection of relapse and monitoring therapy response. Our review analyzes the clinical usefulness of tumor markers applied in most frequent epithelial tumors, based on recent evidence and guidelines.

Serum Tumor Markers in Paraneoplastic Neurologic Syndromes: A Systematic Review of Guidelines

Purpose: Algorithms for the detection of a malignancy in patients with unclear neurologic symptoms of suspicious paraneoplastic origins are not universally applied. Frequently, circulating tumor markers (TMs) are considered a valuable tool for cancer diagnosis in patients with paraneoplastic neurologic syndromes (PNS). Our aim was to extract the recommendations on the use of TMs and onconeural antibodies (Abs) for the diagnosis of malignancies in PNS from clinical practice guidelines and put them forward as evidence in a common framework to facilitate diffusion, dissemination, and implementation.

Methods: Systematic literature searches were performed for guidelines on both oncology and PNS published since 2007. Guidelines containing information and recommendations for clinical practice pertaining to the screening and diagnosis of PNS were selected. Information on circulating TMs and onconeural Abs was extracted and synthesized in consecutive steps of increasing simplification.

Results: We retrieved 799 eligible guidelines on oncology for the potential presence of information on PNS but only six covered treated diagnosis or the screening of cancer in PNS, which were then selected. Seventy-nine potentially relevant guidelines on PNS were identified as eligible and 15 were selected. Synoptic tables were prepared showing that classical TMs are not recommended for the screening or the diagnosis of a malignancy in patients with a suspected PNS. Neither should onconeural Abs be considered to screen for the presence of a malignancy, although they could be helpful to define the probability of the paraneoplastic origin of a neurologic disorder.

Conclusion: The present work of synthesis may be a useful tool in the diffusion, dissemination, and implementation of guideline recommendations, potentially facilitating the decrease of the inappropriate use of circulating biomarkers for cancer screening in the presence of PNS.

The appropriate use of circulating EBV-DNA in nasopharyngeal carcinoma: Comprehensive clinical practice guidelines evaluation

BACKGROUND

In EBV-related nasopharyngeal carcinoma (NPC), quantitative determination of circulating EBV-DNA (cEBV-DNA) can potentially be applied as disease marker. The aim of the study was to investigate if the clinical utility of cEBV-DNA is established in clinical practice guidelines and if recommendations are provided to standardize the quantitative cEBV-DNA determination.

METHODS

A systematic literature search for NPC guidelines published since 2011 was performed. Information for cEBV-DNA detection method and use in clinical practice was synthesized in consecutive steps of increasing simplification.

RESULTS

From 570 titles and abstracts identified by the search, 16 guidelines were included. The selected documents were further clustered as either being based on a systematic literature revision to generate recommendations (4/16) or not (12/16). cEBV-DNA was evaluated in only one guideline based on a systematic revision and in 8 guidelines without systematic revision. Half of available guidelines provide recommendation for its clinical use. Methodological issues on cEBV-DNA determination are discussed by 31% of guidelines, without providing any recommendation on method standardization.

CONCLUSIONS

Due to its prognostic value, cEBV-DNA is suggested in the pre-treatment work-up and in the follow-up. Guideline producers need to take into more consideration methodological aspects impacting the actual reliability and generalizability of laboratory results.

State of the art and trends of circulating cancer biomarkers

The role of biomarkers is crucial in oncology for both early diagnosis and the personalization of cancer treatments. Tissue biomarkers have gained a central role as predictors of the response to an increasing number of anticancer agents; conversely, the clinical role of circulating biomarkers (c-TMs) is limited and has remained almost unchanged over the years. The position of guidelines is summarized and discussed with reference to the potential usefulness of c-TMs in those areas of application that cannot be covered by tissue biomarkers. The pipeline of translational research on biomarkers is briefly described; the differences among analytical validation, clinical validation, and clinical utility are discussed, emphasizing that the assessment of clinical utility is the ultimate step toward clinical use. The role of monitoring of appropriateness as a proxy indicator of how the research pipeline has actually worked is discussed, and data and c-TMs overordering rates are reported. The role and limits of guidelines to influence appropriate c-TMs ordering are discussed. The design of primary studies on c-TMs is examined, underlining that they mainly focus on clinical validation rather than on clinical utility. The role of regulatory boards is also briefly presented and discussed.

Insufficient uptake of systematic search methods in oncological clinical practice guideline: a systematic review

Background

The use of systematic review methods are widely recognized to be essential in the development of recommendations in clinical practice guidelines to prove their trustworthiness. The objective of this study was to assess the use of systematic search methods by authors of guidelines published in the oncology field.

Methods

We analyzed 590 guidance documents identified in PubMed, NGC, GIN and web sites for guidelines in 2009–2015 in oncology. The main outcome measure used was incidence of guidance documents supported by a systematic search of the literature. In addition to descriptive analyses, logistic regression was used to evaluate if adequate search methods were explained by guideline characteristics.

Results

Of 590 guidance documents included in the study, 305 (51.7%) declared the use of systematic search methods but only 168 (28.5%) applied methods meeting minimum standards for quality and provided sufficient details to allow classification. 164 (27.8%) guidance documents did not report any use of literature evaluation.

Guidance documents produced by a Government Agency in North America (OR 2.16, 95% CI 1.16–4.17) and those with a focused scope (OR 2.35, 95% CI 0.97–5.56) were positively associated with the use of systematic search methods. We found no association between the year of publication and use of systematic search methods.

Conclusions

A relatively small number of guidance documents was informed by scientific evidence identified through adequate systematic search methods. We observed substantial room for improvement of applied methods and reporting, especially in documents with a broad focus, or those produced by professional societies or independent expert panels in other continents than North America.

Electronic supplementary material

The online version of this article (10.1186/s12874-019-0818-5) contains supplementary material, which is available to authorized users.

Human Chorionic Gonadotropin Assays for Testicular Tumors: Closing the Gap between Clinical and Laboratory Practice

BACKGROUND

Clinical practice guidelines recommend the measurement of human chorionic gonadotropin (hCG) and/or hCGβ in serum for management of testicular germ cell tumors (GCTs). These guidelines, however, disregard relevant biochemical information on hCG variants to be detected for oncological application. We set out to provide a critical review of the clinical evidence together with a characterization of the selectivity of currently marketed hCG immunoassays, identifying assays suitable for management of GCTs.

CONTENT

Evidence sources in the available literature were critically appraised. Most instances of misdiagnosis and mismanagement of testicular GCTs have been associated with hCG results. According to the clinical evidence, 36% of patients with seminoma show an exclusive hCGβ increase, and 71% of patients with nonseminomatous GCTs (NSGCTs) show an increase of intact hCG and/or hCG + hCGβ, whereas the hCGβ increase in NSGCTs is variable according to the tumor stage and histology.

SUMMARY

hCG + hCGβ assays that display an equimolar recognition of hCG and hCGβ, or at least do not overtly underestimate hCGβ, may be employed for management of testicular GCTs. Assays that underestimate hCGβ are not recommended for oncological application. In addition to the hCG + hCGβ assay in service, an additional assay with broader selectivity for other hCG variants should be considered when false-negative or false-positive results are suspected on the basis of clinical data.

Indicators of inappropriate tumour marker use through the mining of electronic health records

RATIONALE, AIMS, AND OBJECTIVES

Although the issue of monitoring appropriateness of tumour markers (TMs) request in outpatients remains crucial, proper indicators are still demanding. The present study developed and explored indicators of inappropriate TM ordering in outpatients through the data mining of electronic health records (EHRs).

METHODS

Carcinoembryonic antigen (CEA), alfa-fetoprotein (AFP), carbohydrate antigen (CA)125, CA15.3, CA19.9, and prostate-specific antigen (PSA) ordered in outpatients during a year were examined by mining EHRs of a Local Health Authority in Italy. Evidence-based criteria were used to develop performance indicators. Demographic and clinical information associated with TM orders were examined.

RESULTS

A total of 80 813 TMs were ordered in 52 536 outpatients (1.54 markers/patient). Indicators related to disease codes, gender, age, and TM repetitions were developed, and their application showed that (1) CA15.3 and CEA are prevalently requested in patients with cancer (79.2% and 65.6%) whereas the other TMs are largely requested also in patients without cancer; (2) requests of PSA in women and of CA125 or CA15.3 in men are negligible; (3) although requests in people older than 80 years are relevant (16.4% of total), the highest rate of request of all markers occurs in patients aged 40 to 79 years; (4) CA15.3 and CEA are mainly requested in cancer cases between 50 and 79 years and AFP, CA19.9, and CA125 in those between 60 and 69 years; (5) <50% of PSA orders are associated with cancer code for all age intervals; and (6) multiple repetitions of AFP, CA125, CA15.3, CA19.9, and CEA are prevalent in cancer patients or benign diseases to which TMs are appropriate, whereas PSA repetitions occur mainly in patients without cancer.

CONCLUSIONS

The developed indicators resulted suitable to monitor TM overordering in outpatients through the mining of EHRs. The present study is a first approach towards the use of big-data mining for TM appropriateness evaluation purposes.

YAP, TAZ and AREG expression in eighth cranial nerve schwannoma

BACKGROUND

Although the diagnosis and treatment of eighth cranial nerve (VIII CN) schwannoma (acoustic neuroma) has improved over the years, no factors capable of predicting tumor growth have been identified as yet. This study is a preliminary investigation of the expression in sporadic VIII CN schwannomas of Yes-associated protein (YAP), transcriptional coactivator with PDZ-binding motif (TAZ), and amphiregulin (AREG), a direct target gene of YAP and TAZ. The expression of YAP, TAZ and AREG was correlated with the volumetric dimensions of tumors on contrast-enhanced magnetic resonance imaging (ceMRI).

METHODS

YAP, TAZ and AREG expression was assessed immunohistochemically in surgical specimens of 36 consecutive sporadic VIII CN schwannomas. 3D reconstructions of the tumors and their corresponding volumes in cm3 were obtained from measurements on ceMRI images using the OsiriX® software.

RESULTS

We found a significant direct correlation between TAZ expression and VIII CN schwannoma volumes on latest preoperative ceMRI (p<0.0003). Mean TAZ expression was also significantly higher in VIII CN schwannomas with a volume ≥2.1 cm3 than in those with a volume <2.1 cm3(p<0.0018). No significant correlations emerged for YAP or AREG expression and VIII CN schwannoma volume.

CONCLUSIONS

The immunohistochemical expression of TAZ (but not YAP or AREG) correlated significantly with schwannoma volume measured on ceMRI. Further investigations are needed to identify the biological factors influencing tumor proliferation (ideally secreted proteins like AREG) that might be detected using non-invasive approaches (i.e., blood samples).

Appropriateness of tumor marker request: a case of study

Appropriateness is crucial to provide efficient and high-quality health services at affordable costs. Laboratory medicine is a sector of special interest for the investigation of inappropriateness, due to the high rate of technological innovation and its pivotal role in many diseases and clinical settings. Some subjective aspects related to either the patient or physician seem to have a major role on inappropriateness rates. Given the psychological impact of cancer on both patients and physicians, tumor markers represent a case of study for appropriateness. The assessment of inappropriateness of laboratory tests has been focused mainly on ordering patterns. Appropriateness can barely be appraised by matching the requested test with the clinical problem because clinical information on the test requisition form is usually inadequate. Monitoring inappropriateness through individual clinical information may be feasible in inpatient (clinical data are available), while an indirect approach should be used for outpatients. To estimate inappropriateness in outpatients our group developed innovative models based on comparison between the actually ordered and expected requests of tumor marker, calculated according to recommendations of clinical practice guidelines (CPGs) applied to figures of cancer prevalence. The implementation of the model at national scale in Italy led to recognize a very high rate of overordering of tumor markers. The model was further focused by a dedicated algorithm to be adapted to different clinical conditions or organizational settings by applying performance indicators to cohort-wide structured information in electronic health records (EHRs). With this novel approach, we showed that inappropriateness is multifaceted even within the specific category of tumour markers. The model was effective in identifying both over- and underordering. Implementation of evidence based information and monitoring their impact on the clinical practice are parts of the same, multistage, process aimed at the progressive improvement of health care.