Effect of the staging schema on melanoma cancer reporting, 1999 to 2006

BackgroundStaging schemas have changed multiple times over the past 10 years.ObjectiveWe sought to examine the impact of staging schemas on the distribution of stages at diagnosis over time.MethodsWe examined the stage at diagnosis for melanoma cancer cases diagnosed between 1999 and 2006 using data provided by the Surveillance, Epidemiology, and End Results (SEER) and National Program of Cancer Registries (NPCR) programs. The staging schemas were summary staging 1977 (SS1977), summary staging 2000 (SS2000), derived SS2000, and SEER historic staging systems.ResultsMelanoma was predominantly staged as a localized disease in all schemas. Using SEER data, the proportion of localized melanomas diagnosed in 2001 to 2003 using SS2000 was about 2.5% lower than the proportion diagnosed in 1999 to 2000 using SS1977, whereas the proportion of cases staged as regional was 2.7% higher using the SS2000 than SS1977. The distribution of stages for cases diagnosed in 2001 to 2003 using SS2000 was similar to that for cases diagnosed in 2004 to 2006 using a derived SS2000. Shift in stage distribution among SS1977, SS2000, and SEER historic staging was found to be about 6% (localized to regional) and about 17.5% (unknown to regional stage). The distribution of changes in stage observed for the SEER cases was not evident for cases from NPCR.LimitationsSEER historic staging was not available for NPCR cases.ConclusionChanges in staging rules resulted in cases being moved from the localized to the regional stage and from unknown to the regional stage. Without staging rules that have been consistently applied to melanomas over many years, surveillance of prevention, treatment, and control of this condition is difficult.