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Evaluation of the Number-Needed-to-Biopsy Metric for the Diagnosis of Cutaneous MelanomaA Systematic Review and Meta-analysis

Educational Objective
To understand the number needed to biopsy (NNB) among clinicians for cutaneous melanoma.
1 Credit CME
Key Points

Question  Does the number-needed-to-biopsy for cutaneous melanoma differ among clinicians according to the medical literature?

Findings  In this systematic review of 46 articles on the number-needed-to-biopsy metric for melanoma diagnosis, the number ranged from 2.2 to 287.

Meaning  The number needed to biopsy appeared to vary significantly across geographic regions and according to prevalence of disease and clinician characteristics, including level of training, age, and use of dermoscopy; standardization of NNB and its reporting may be warranted.


Importance  To date, no concerted effort has been made to date to evaluate the literature on number-needed-to-biopsy (NNB) metrics, particularly to account for the differences in clinician type and melanoma prevalence in certain geographic locations.

Objective  To review and synthesize worldwide data for NNB for the diagnosis of cutaneous melanoma.

Data Source  MEDLINE, Embase, and PubMed databases were searched for English-language articles published worldwide from January 1, 2000, to November 28, 2018.

Study Selection  A total of 46 studies were included that addressed NNB for at least 3681 clinicians worldwide and included 455 496 biopsied tumors and 29 257 melanomas; primary care practitioner (PCP) data were only available from Australia.

Data Extraction and Synthesis  Articles were screened for eligibility, and possible overlapping data sets were resolved. Data extracted included clinician specialization, use of dermoscopy, geographic region and location-specific health care system, study design, number of benign tumors, number of melanomas, and NNB. The review followed the PRISMA guidelines.

Main Outcome and Measures  The NNB for the diagnosis of cutaneous melanoma.

Results  A total of 46 studies were included that addressed NNB for at least 3681 clinicians worldwide and included 455 496 biopsied tumors and 29 257 melanomas; primary care practitioner (PCP) data were only available from Australia. The reported NNB ranged from 2.2 to 287, and the weighted mean NNB for all included publications was 15.6. The exclusion of publications structured as all biopsied tumors, owing to variable data characterization, resulted in reported NNB ranging from 2.2 to 30.5, with a global weighted mean NNB of 14.8 for all clinicians, 7.5 for all dermatologists, 14.6 for Australian PCPs, and 13.2 for all US-based dermatological practitioners, including dermatologists and advanced practice professionals. The summary effect size (ES) demonstrates that a mean 4% of biopsies demonstrated melanoma for study stratum A (all biopsied skin tumors, ES, 0.04; 95% CI, 0.03-0.05), and a mean 12% of biopsies demonstrated melanoma for study strata B (melanocytic tumors on pathology review, ES, 0.12; 95% CI, 0.10-0.14) and C (clinical concern for melanoma, ES; 0.12; 95% CI, 0.09-0.14).

Conclusions and Relevance  The existing NNB for cutaneous melanoma appeared to vary widely worldwide, lacking standardization in the metric and its reporting, and according to clinician characteristics as well; the NNB of US-based clinicians may warrant further exploration.

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Article Information

Accepted for Publication: April 26, 2019.

Corresponding Author: Kelly C. Nelson, MD, MD Anderson Cancer Center, Department of Dermatology, The University of Texas, 1400 Pressler St, Unit 1452, Houston, TX 77030 (kcnelson1@mdanderson.org).

Published Online: July 10, 2019. doi:10.1001/jamadermatol.2019.1514

Author Contributions: Drs Nelson and Curiel-Lewandrowski had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Nelson, Swetter, Chen, Curiel-Lewandrowski, MD.

Acquisition, analysis, or interpretation of data: Nelson, Saboda, Curiel-Lewandrowski.

Drafting of the manuscript: Nelson, Curiel-Lewandrowski.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Nelson, Saboda.

Obtained funding: Nelson.

Administrative, technical, or material support: Curiel-Lewandrowski.

Supervision: Curiel-Lewandrowski.

Conflict of Interest Disclosures: Dr Curiel-Lewandrowski reported grants from Amgen and personal fees from Novartis outside of the submitted work. No other disclosures were reported.

Funding/Support: This study was supported by the philanthropic contributions of the Lyda Hill Foundation to The University of Texas MD Anderson Cancer Center Moon Shots Program.

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Additional Contributions: The authors recognize the invaluable assistance of Gregory F Pratt, DDS, MSLS, Research Medical Librarian, MD Anderson Cancer Center, in the structuring of the systematic literature review search. Dr Pratt received no additional compensation, outside of his usual salary, for his contributions.

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