The recently updated American Joint Committee on Cancer (AJCC) Cancer Staging Manual, 8th edition (AJCC 8), shows greater reproducibility and higher concordance with a reference standard compared with AJCC 7, according to results published in JAMA Network Open.
The results suggest that an improved classification of invasive melanoma can be expected with the implementation of AJCC 8, which will likely lead to a positive patient impact. However, the researchers noted that although the AJCC 8 has improvements compared with AJCC 7, concordance and reproducibility remain low.
The AJCC 8 includes revisions to definitions of T1a vs T1b or greater.
For this study, 187 pathologists who interpret melanocytic skin lesions in their practices completed 4342 independent case interpretations of 116 invasive melanoma cases. A consensus reference diagnosis and participating pathologists’ interpretations were classified into the Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis class IV (T1a) or class V (T1b), using both the AJCC 7 and AJCC 8 criteria.
For T1a diagnoses, participating pathologists’ concordance with the consensus reference diagnosis increased from 44% with AJCC 7 criteria (95% CI, 41%-48%) to 54% (95% CI, 51%-57%), using AJCC 8 criteria.
For cases of T1b or greater, pathologists’ concordance increased from 72% (95% CI, 69%-75%) with AJCC 7 criteria to 78% (95% CI, 75%-80%) with AJCC 8 criteria.
Intraobserver reproducibility of diagnoses increased from 59% (95% CI, 56%-63%), using AJCC 7 criteria, to 64% (95% CI, 62%-67%) using AJCC 8 criteria, for T1a invasive melanoma, and from 74% (95% CI, 71%-76%) to 77% (95% CI, 74%-79%) for invasive melanoma cases that were T1b or greater.
Disclosures: Dr Elder reported serving as a consultant for Myriad Genetics and SciBase and receiving research funding from the National Institutes of Health/National Cancer Institute. Dr Barnhill reported a financial relationship with Myriad Genetics. Dr Longton reported receiving grants from Fred Hutchinson Cancer Research Center and the National Cancer Institute during the conduct of the study. Dr Titus, Dr Weinstock, Dr Pepe, and Dr Piepkorn reported receiving grants from the National Cancer Institute during the conduct of the study.
Elmore JG, Elder DE, Barnhill RL, et al. Concordance and reproducibility of melanoma staging according to the 7th versus 8th edition of the AJCC Cancer Staging Manual. JAMA Network Open. 2018;1(1):e180083.