Updated staging criteria yield "modest" improvement in melanoma diagnosis


By Marilynn Larkin

NEW YORK (Reuters Health) - New criteria for staging melanoma, from the American Joint Committee on Cancer (AJCC), will likely have a positive effect on patients, but concordance and reproducibility "remain low," researchers say.

Dr. Joann Elmore of the David Geffen School of Medicine, University of California, Los Angeles and colleagues analyzed interpretations by 187 U.S. pathologists of 4,342 slides representing 116 melanoma cases. Concordance with a reference diagnosis was compared using both AJCC7 and AJCC8 criteria.

As reported online May 18 in JAMA Network Open, for T1a diagnoses, concordance with the consensus reference diagnosis increased from 44% using AJCC7 to 54% using AJCC8 criteria. Concordance for cases of T1b or greater increased from 72% to 78%.

Intraobserver reproducibility of diagnoses improved as well, increasing from 59% to 64% for T1a invasive melanoma, and from 74% to 77% for T1b or greater invasive melanoma cases.

"Even modest improvements of 6% to 10% in diagnostic concordance resulting from changes from AJCC 7 to AJCC 8 are important," the authors state. "However, despite improvement, concordance and reproducibility remain low and suggest that conventional histopathology has been parsed to a degree that falls below the limits of reliability for the demands and consequences of the staging schemata that have evolved over time."

"The low accuracy that we see in diagnosing melanoma is very concerning and has significant implications for patient care and outcomes," Dr. Elmore told Reuters Health by email.

"My own research has been about turning the microscope back on ourselves to see how we, as physicians, can improve our diagnoses," she said. "The longer I continue this line of research, the more I realize how challenging it truly is."

"Given the diagnostic uncertainty surrounding certain kinds of melanocytic skin lesions (e.g. diagnoses in the middle of the disease spectrum, difficult cases), clinicians should remind patients that medicine is, at times, a science of uncertainty," she noted. Dr. Elmore herself experienced the fear of having been (incorrectly) told she had melanoma (http://blogs.bmj.com/bmj/2017/06/28/joann-elmore-when-diagnostic-uncertainty-hits-home/).

"We are currently studying second opinion strategies as well as computer machine learning to find out if these aid in increasing accuracy," she said.

Dr. Richard Scolyer of Royal Prince Alfred Hospital in New South Wales, coauthor of a related editorial, told Reuters Health by email, "The results from this study suggest that the new 8th edition AJCC melanoma staging system will enhance the accuracy and reproducibility of melanoma staging, which will translate into improvements in patient care."

In their editorial, Dr. Scolyer and colleagues suggest, "Future studies could investigate the reproducibility of each parameter required by AJCC 8 or pathological factors proposed for inclusion in subsequent iterations, and how this may be influenced by the experience of the reporting pathologist (e.g., by the nature and number of melanocytic cases evaluated per year) and/or the availability of relevant clinical and molecular information."

"Such studies could potentially inform future editions of the AJCC melanoma staging system and contribute to improved accuracy in the pathological staging of patients with melanoma," they conclude.

SOURCE: http://bit.ly/2sp4owI and http://bit.ly/2H4oOjY

JAMA Network Open 2018.

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