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Context.— The process for identifying patients with monoclonal gammopathies is complex. Initial detection of a monoclonal immunoglobulin protein (M protein) in the serum or urine often requires compilation of analytical data from several areas of the laboratory. The detection of M proteins depends on adequacy of the sample provided, available clinical information, and the laboratory tests used. Objective.— To develop an evidence-based guideline for the initial laboratory detection of M proteins. Design.— To develop evidence-based recommendations, the College of American Pathologists convened a panel of experts in the diagnosis and treatment of monoclonal gammopathies and the laboratory procedures used for the initial detection of M proteins. The panel conducted a systematic literature review to address key questions. Using the Grading of Recommendations Assessment, Development, and Evaluation approach, recommendations were created based on the available evidence, strength of that evidence, and key judgements as defined in the Grading of Recommendations Assessment, Development, and Evaluation Evidence to Decision framework. Results.— Nine guideline statements were established to optimize sample selection and testing for the initial detection and quantitative measurement of M proteins used to diagnose monoclonal gammopathies. Conclusions.— This guideline was constructed to harmonize and strengthen the initial detection of an M protein in patients displaying symptoms or laboratory features of a monoclonal gammopathy. It endorses more comprehensive initial testing when there is suspicion of amyloid light chain amyloidosis or neuropathies, such as POEMS (polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes) syndrome, associated with an M protein.

Context.—The performance of laboratory testing has recently come under increased scrutiny as part of important and ongoing debates on regulation and reimbursement. To address this critical issue, this study compares the performance of assay methods, using either commercial kits or assays designed and implemented by single laboratories (“home brews”), including next-generation sequencing methods, on proficiency testing provided by the College of American Pathologists Molecular Oncology Committee.Objective.—To compare the performance of different assay methods on College of American Pathologists proficiency testing for variant analysis of 3 common oncology analytes: BRAF, EGFR, and KRAS.Design.—There were 6897 total responses across 35 different proficiency testing samples interrogating 13 different variants as well as wild-type sequences for BRAF, EGFR, and KRAS. Performance was analyzed by test method, kit manufacturer, variants tested, and preanalytic and postanalytic practices.Results.—Of 26 reported commercial kits, 23 achieved greater than 95% accuracy. Laboratory-developed tests with no kit specified demonstrated 96.8% or greater accuracy across all 3 analytes (1123 [96.8%] acceptable of 1160 total responses for BRAF; 848 [97.5%] acceptable of 870 total responses for EGFR; 942 [97.0%] acceptable of 971 total responses for KRAS). Next-generation sequencing platforms (summed across all analytes and 2 platforms) demonstrated 99.4% accuracy for these analytes (165 [99.4%] acceptable of 166 total next-generation sequencing responses). Slight differences in performance were noted among select commercial assays, dependent upon the particular design and specificity of the assay. Wide differences were noted in the lower limits of neoplastic cellularity laboratories accepted for testing.Conclusions.—These data demonstrate the high degree of accuracy and comparable performance across all laboratories, regardless of methodology. However, care must be taken in understanding the diagnostic specificity and reported analytic sensitivity of individual methods.

Context.— Detection of acquired variants in cancer is a paradigm of precision medicine, yet little has been reported about clinical laboratory practices across a broad range of laboratories. Objective.— To use College of American Pathologists proficiency testing survey results to report on the results from surveys on next-generation sequencing–based oncology testing practices. Design.— College of American Pathologists proficiency testing survey results from more than 250 laboratories currently performing molecular oncology testing were used to determine laboratory trends in next-generation sequencing–based oncology testing. Results.— These presented data provide key information about the number of laboratories that currently offer or are planning to offer next-generation sequencing–based oncology testing. Furthermore, we present data from 60 laboratories performing next-generation sequencing–based oncology testing regarding specimen requirements and assay characteristics. The findings indicate that most laboratories are performing tumor-only targeted sequencing to detect single-nucleotide variants and small insertions and deletions, using desktop sequencers and predesigned commercial kits. Despite these trends, a diversity of approaches to testing exists. Conclusions.— This information should be useful to further inform a variety of topics, including national discussions involving clinical laboratory quality systems, regulation and oversight of next-generation sequencing–based oncology testing, and precision oncology efforts in a data-driven manner.