Catharine M. Sturgeon

American Society of Clinical Oncology/College of American Pathologists Guideline Recommendations for Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer

PURPOSE To develop a guideline to improve the accuracy of human epidermal growth factor receptor 2 (HER2) testing in invasive breast cancer and its utility as a predictive marker. METHODS The American Society of Clinical Oncology and the College of American Pathologists convened an expert panel, which conducted a systematic review of the literature and developed recommendations for optimal HER2 testing performance. The guideline was reviewed by selected experts and approved by the board of directors for both organizations. RESULTS Approximately 20% of current HER2 testing may be inaccurate. When carefully validated testing is performed, available data do not clearly demonstrate the superiority of either immunohistochemistry (IHC) or in situ hybridization (ISH) as a predictor of benefit from anti-HER2 therapy. RECOMMENDATIONS The panel recommends that HER2 status should be determined for all invasive breast cancer. A testing algorithm that relies on accurate, reproducible assay performance, including newly available types of brightfield ISH, is proposed. Elements to reliably reduce assay variation (for example, specimen handling, assay exclusion, and reporting criteria) are specified. An algorithm defining positive, equivocal, and negative values for both HER2 protein expression and gene amplification is recommended: a positive HER2 result is IHC staining of 3+ (uniform, intense membrane staining of > 30% of invasive tumor cells), a fluorescent in situ hybridization (FISH) result of more than six HER2 gene copies per nucleus or a FISH ratio (HER2 gene signals to chromosome 17 signals) of more than 2.2; a negative result is an IHC staining of 0 or 1+, a FISH result of less than 4.0 HER2 gene copies per nucleus, or FISH ratio of less than 1.8. Equivocal results require additional action for final determination. It is recommended that to perform HER2 testing, laboratories show 95% concordance with another validated test for positive and negative assay values. The panel strongly recommends validation of laboratory assay or modifications, use of standardized operating procedures, and compliance with new testing criteria to be monitored with the use of stringent laboratory accreditation standards, proficiency testing, and competency assessment. The panel recommends that HER2 testing be done in a CAP-accredited laboratory or in a laboratory that meets the accreditation and proficiency testing requirements set out by this document.

American Society of Clinical Oncology/College of American Pathologists guideline recommendations for human epidermal growth factor receptor 2 testing in breast cancer

PURPOSE To develop a guideline to improve the accuracy of human epidermal growth factor receptor 2(HER2) testing in invasive breast cancer and its utility as a predictive marker. METHODS The American Society of Clinical Oncology and the College of American Pathologists convened an expert panel, which conducted a systematic review of the literature and developed recommendations for optimal HER2 testing performance. The guideline was reviewed by selected experts and approved by the board of directors for both organizations. RESULTS Approximately 20% of current HER2 testing may be inaccurate. When carefully validated testing is performed, available data do not clearly demonstrate the superiority of either immunohistochemistry(IHC) or in situ hybridization (ISH) as a predictor of benefit from anti-HER2 therapy. RECOMMENDATIONS The panel recommends that HER2 status should be determined for all invasive breast cancer. A testing algorithm that relies on accurate, reproducible assay performance, including newly available types of brightfield ISH, is proposed. Elements to reliably reduce assay variation (for example, specimen handling, assay exclusion, and reporting criteria) are specified. An algorithm defining positive, equivocal, and negative values for both HER2 protein expression and gene amplification is recommended: a positive HER2 result is IHC staining of 3 + (uniform, intense membrane staining of 30% of invasive tumor cells), a fluorescent in situ hybridization (FISH) result of more than six HER2 gene copies per nucleus or a FISH ratio (HER2 gene signals to chromosome 17 signals) of more than 2.2; a negative result is an IHC staining of 0 or 1 +, a FISH result of less than 4.0 HER2 gene copies per nucleus, or FISH ratio of less than 1.8. Equivocal results require additional action for final determination. It is recommended that to perform HER2 testing, laboratories show 95% concordance with another validated test for positive and negative assay values. The panel strongly recommends validation of laboratory assay or modifications, use of standardized operating procedures, and compliance with new testing criteria to be monitored with the use of stringent laboratory accreditation standards, proficiency testing, and competency assessment. The panel recommends that HER2 testing be done in a CAP-accredited laboratory or in a laboratory that meets the accreditation and proficiency testing requirements set out by this document.

National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for use of tumor markers in testicular, prostate, colorectal, breast, and ovarian cancers

BACKGROUND Updated National Academy of Clinical Biochemistry (NACB) Laboratory Medicine Practice Guidelines for the use of tumor markers in the clinic have been developed. METHODS Published reports relevant to use of tumor markers for 5 cancer sites--testicular, prostate, colorectal, breast, and ovarian--were critically reviewed. RESULTS For testicular cancer, alpha-fetoprotein, human chorionic gonadotropin, and lactate dehydrogenase are recommended for diagnosis/case finding, staging, prognosis determination, recurrence detection, and therapy monitoring. alpha-Fetoprotein is also recommended for differential diagnosis of nonseminomatous and seminomatous germ cell tumors. Prostate-specific antigen (PSA) is not recommended for prostate cancer screening, but may be used for detecting disease recurrence and monitoring therapy. Free PSA measurement data are useful for distinguishing malignant from benign prostatic disease when total PSA is <10 microg/L. In colorectal cancer, carcinoembryonic antigen is recommended (with some caveats) for prognosis determination, postoperative surveillance, and therapy monitoring in advanced disease. Fecal occult blood testing may be used for screening asymptomatic adults 50 years or older. For breast cancer, estrogen and progesterone receptors are mandatory for predicting response to hormone therapy, human epidermal growth factor receptor-2 measurement is mandatory for predicting response to trastuzumab, and urokinase plasminogen activator/plasminogen activator inhibitor 1 may be used for determining prognosis in lymph node-negative patients. CA15-3/BR27-29 or carcinoembryonic antigen may be used for therapy monitoring in advanced disease. CA125 is recommended (with transvaginal ultrasound) for early detection of ovarian cancer in women at high risk for this disease. CA125 is also recommended for differential diagnosis of suspicious pelvic masses in postmenopausal women, as well as for detection of recurrence, monitoring of therapy, and determination of prognosis in women with ovarian cancer. CONCLUSIONS Implementation of these recommendations should encourage optimal use of tumor markers.

Tumor markers in pancreatic cancer: a European Group on Tumor Markers (EGTM) status report

Pancreatic ductal adenocarcinoma is one of the most difficult malignancies to diagnose and treat. The aim of this article is to review how tumor markers can aid the diagnosis and management of patients with this malignancy. The most widely used and best validated marker for pancreatic cancer is CA 19-9. Inadequate sensitivity and specificity limit the use of CA 19-9 in the early diagnosis of pancreatic cancer. In non-jaundiced patients, however, CA 19-9 may complement other diagnostic procedures. In patients with resectable pancreatic cancer, presurgical and postresection CA 19-9 levels correlate with overall survival. In advanced disease, elevated pretreatment levels of CA 19-9 are associated with adverse patient outcome and thus may be combined with other factors for risk stratification. Most, but not all, reports indicate that serial levels of CA 19-9 correlate with response to systemic therapy. Use of CA 19-9 kinetics in conjunction with imaging is therefore recommended in monitoring therapy. Although several potential serum and tissue markers for pancreatic cancer are currently undergoing evaluation, none are sufficiently validated for routine clinical use. CA 19-9 thus remains the serum pancreatic cancer marker against which new markers for this malignancy should be judged.

Roadmap for Harmonization of Clinical Laboratory Measurement Procedures

Results between different clinical laboratory measurement procedures (CLMP) should be equivalent, within clinically meaningful limits, to enable optimal use of clinical guidelines for disease diagnosis and patient management. When laboratory test results are neither standardized nor harmonized, a different numeric result may be obtained for the same clinical sample. Unfortunately, some guidelines are based on test results from a specific laboratory measurement procedure without consideration of the possibility or likelihood of differences between various procedures. When this happens, aggregation of data from different clinical research investigations and development of appropriate clinical practice guidelines will be flawed. A lack of recognition that results are neither standardized nor harmonized may lead to erroneous clinical, financial, regulatory, or technical decisions. Standardization of CLMPs has been accomplished for several measurands for which primary (pure substance) reference materials exist and/or reference measurement procedures (RMPs) have been developed. However, the harmonization of clinical laboratory procedures for measurands that do not have RMPs has been problematic owing to inadequate definition of the measurand, inadequate analytical specificity for the measurand, inadequate attention to the commutability of reference materials, and lack of a systematic approach for harmonization. To address these problems, an infrastructure must be developed to enable a systematic approach for identification and prioritization of measurands to be harmonized on the basis of clinical importance and technical feasibility, and for management of the technical implementation of a harmonization process for a specific measurand.

National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for Use of Tumor Markers in Liver, Bladder, Cervical, and Gastric Cancers

BACKGROUND Updated National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for the use of tumor markers in the clinic have been developed. METHODS Published reports relevant to use of tumor markers for 4 cancer sites--liver, bladder, cervical, and gastric--were critically reviewed. RESULTS Alpha-fetoprotein (AFP) may be used in conjunction with abdominal ultrasound for early detection of hepatocellular carcinoma (HCC) in patients with chronic hepatitis or cirrhosis associated with hepatitis B or C virus infection. AFP concentrations >200 microg/L in cirrhotic patients with typical hypervascular lesions >2 cm in size are consistent with HCC. After a diagnosis of HCC, posttreatment monitoring with AFP is recommended as an adjunct to imaging, especially in the absence of measurable disease. Although several urine markers have been proposed for bladder cancer, none at present can replace routine cystoscopy and cytology in the management of patients with this malignancy. Some may, however, be used as complementary adjuncts to direct more effective use of clinical procedures. Although carcinoembryonic antigen and CA 19-9 have been proposed for use gastric cancer and squamous cell carcinoma antigen for use in cervical cancer, none of these markers can currently be recommended for routine clinical use. CONCLUSIONS Implementation of these recommendations should encourage optimal use of tumor markers for patients with liver, bladder, cervical, or gastric cancers.

National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for Use of Tumor Markers in Clinical Practice: Quality Requirements

BACKGROUND This report presents updated National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines summarizing quality requirements for the use of tumor markers. METHODS One subcommittee developed guidelines for analytical quality relevant to serum and tissue-based tumor markers in current clinical practice. Two other subcommittees formulated recommendations particularly relevant to the developing technologies of microarrays and mass spectrometry. RESULTS Prerequisites for optimal use of tumor markers in routine practice include formulation of the correct clinical questions to ensure selection of the appropriate test, adherence to good clinical and laboratory practices (e.g., minimization of the risk of incorrect patient and/or specimen identification, tube type, or timing), use of internationally standardized and well-characterized methods, careful adherence to manufacturer instructions, and proactive and timely reactions to information derived from both internal QC and proficiency-testing specimens. Highly desirable procedures include those designed to minimize the risk of the reporting of erroneous results attributable to interferences such as heterophilic antibodies or hook effects, to facilitate the provision of informative clinical reports (e.g., cumulative and/or graphical reports, appropriately derived reference intervals, and interpretative comments), and when possible to integrate these reports with other patient information through electronic health records. Also mandatory is extensive validation encompassing all stages of analysis before introduction of new technologies such as microarrays and mass spectrometry. Provision of high-quality tumor marker services is facilitated by dialogue involving researchers, diagnostic companies, clinical and laboratory users, and regulatory agencies. CONCLUSIONS Implementation of these recommendations, adapted to local practice, should encourage optimization of the clinical use of tumor markers.

Tumor markers in colorectal cancer, gastric cancer and gastrointestinal stromal cancers: European group on tumor markers 2014 guidelines update.

Biomarkers currently play an important role in the detection and management of patients with several different types of gastrointestinal cancer, especially colorectal, gastric, gastro‐oesophageal junction (GOJ) adenocarcinomas and gastrointestinal stromal tumors (GISTs). The aim of this article is to provide updated and evidence‐based guidelines for the use of biomarkers in the different gastrointestinal malignancies. Recommended biomarkers for colorectal cancer include an immunochemical‐based fecal occult blood test in screening asymptomatic subjects ≥50 years of age for neoplasia, serial CEA levels in postoperative surveillance of stage II and III patients who may be candidates for surgical resection or systemic therapy in the event of distant metastasis occurring, K‐RAS mutation status for identifying patients with advanced disease likely to benefit from anti‐EGFR therapeutic antibodies and microsatellite instability testing as a first‐line screen for subjects with Lynch syndrome. In advanced gastric or GOJ cancers, measurement of HER2 is recommended in selecting patients for treatment with trastuzumab. For patients with suspected GIST, determination of KIT protein should be used as a diagnostic aid, while KIT mutational analysis may be used for treatment planning in patients with diagnosed GISTs.

Differences in Recognition of the 1st WHO International Reference Reagents for hCG-Related Isoforms by Diagnostic Immunoassays for Human Chorionic Gonadotropin

BACKGROUND The 1st WHO International Reference Reagents (IRRs) for 6 human chorionic gonadotropin (hCG)-related molecular variants, highly purified and calibrated in substance concentrations by the IFCC Working Group for hCG, permit experimental elucidation of what commercially available hCG methods measure in molar terms and enable assessment of their fitness for clinical purposes. METHODS Pools containing known amounts of the IRRs spiked into normal human serum were issued to participants through the UK National External Quality Assessment Service for hCG for a period of 7 years. Among 16 assays used, 4 recognized only hCG, whereas 6 recognized hCG and its free beta-subunit (hCGbeta), and 6 recognized hCG, hCGbeta, and the beta core fragment. RESULTS Differences in calibration of current hCG assays are moderate. Mean recovery of the current International Standard (IS), hCG IS 75/589, was 107% (range 93% to 126%), whereas that of the IRR 99/688 for hCG was 139% (range 109%-164%). Between-method variation for the latter (CV 12.3%) was also greater than for IS 75/589 (CV 8.8%). Recognition of hCGbeta varied markedly (CV 37%). Most assays overestimated it, but 2 RIAs produced results that were slight underestimations. Recognition of the beta core fragment was even more variable (CV 57%) and was closest to equimolarity for the RIAs. CONCLUSIONS Assays for hCG show considerable variation in their recognition of various forms of hCG, and this variability is the most important cause of method-related differences in hCG results in serum and an even more important cause of method-related differences in urine measurements. Equimolar recognition of the major hCG isoforms is essential if between-method comparability for hCG is to be improved.

Analytical error and interference in immunoassay: minimizing risk

Although generally robust, immunoassays remain vulnerable to occasional analytical errors that may have serious implications for patient care. Sporadic errors that occur as a result of properties of the specimen are particularly difficult to detect. They may be due to the presence of cross-reacting substances, antianalyte antibodies or antireagent antibodies, all of which may lead to erroneously high or low results. Low results may be observed for tumour markers due to high-dose hooking in the presence of very high analyte concentrations. Erroneous results can occur unexpectedly with any specimen and there is no practical means of identifying specimens likely to cause problems in immunoassays. The possibility of interference should always be considered when results do not appear to be in accord with the clinical picture. Errors can occur in even the best-managed laboratories and their early investigation is always desirable. If there is any doubt whatsoever about a result, clinical staff should be encouraged to contact the laboratory. Investigations for possible interference that can be undertaken in most laboratories include testing for linearity on dilution, recovery experiments, treatment with heterophilic blocking tubes and confirmation using a different method. It may be desirable to consult specialist laboratories if more complex studies are necessary. Informing clinical and laboratory staff of the ever-present possibility of unexpected interference, ensuring brief clinical details are available to laboratory staff, and above all facilitating excellent communication between laboratory and clinical staff are key to minimizing the risk of clinical mismanagement due to unsuspected interference.