Reproducibility of AJCC staging parameters in primary cutaneous melanoma: an analysis of 4,924 cases

Pathology reports are of critical importance for conveying information to clinicians who must make important management decisions for their patients. This study sought to assess and compare the precision, reproducibility, and completeness of external pathology reports and pathology reports generated by central review of each case in a large cohort of primary cutaneous melanoma patients.

Details of matched external pathology reports and corresponding review reports for 4,924 primary cutaneous invasive melanomas diagnosed and treated at Melanoma Institute Australia (MIA) between 2001 and 2011 were analyzed.

Interobserver agreement was excellent for American Joint Committee on Cancer (AJCC) T staging parameters: Breslow thickness (intraclass correlation coefficient [ICC] 0.984), mitotic rate (ICC 0.833), and ulceration (kappa statistic [κ] 0.823). All three of these important pathologic variables were included in 92.4 and 66.9% of review (MIA) and external (non-MIA) pathology reports, respectively. Completeness of MIA and non-MIA pathology reports for the three essential T-staging criteria increased significantly from 87.9 to 94.6% (χ(2) = 9.1, df = 1, P = 0.003) and from 53.2 to 74.3% (χ(2) = 35.0, df = 1, P < 0.001) over the 10-year study period. The AJCC N staging parameter of microsatellites was recorded in only 43% of non-MIA reports and demonstrated moderate concordance (κ = 0.560).

Reproducibility and completeness of pathology reports for many important histopathologic features have improved in recent years. Nevertheless, the documentation of microsatellites remained poor in external pathology reports. To enhance the usefulness of the pathology report for the provision of optimal melanoma patient care, continued efforts to encourage pathologists to document its key features appear warranted.