Estimates of stage-specific survival are altered by changes in the 2002 American Joint Committee on Cancer staging system for melanoma

Background: The objectives of the current study were to examine how the estimated stage-specific survival is altered in the 2002 American Joint Committee on Cancer (AJCC) melanoma staging system compared with the 1997 AJCC staging system and to contrast the predictive accuracy of the 2 staging systems.

Methods: There were 5847 consecutive melanoma patients who presented to Memorial Sloan-Kettering Cancer Center from 1996 to 2004 and who were entered prospectively into a data base. These patients were staged according to both the 1997 and 2002 AJCC staging criteria. Overall survival estimates were determined using the Kaplan-Meier method. The overall predictive accuracy of the two staging systems was compared using concordance estimation.

Results: In total, 1035 patients were shifted to a lower stage in the 2002 staging system, whereas only 15 patients were upstaged. The number of patients with Stage I melanoma increased by 697 under the 2002 system (n = 2166 patients) compared with the 1997 system (n = 1463 patients). Because of the changes in 2002, the estimated 5-year overall survival for patients with Stage II melanoma decreased considerably, from 79% (1997) to 64% (2002). With the initiation of subgroups in 2002, it became apparent that patients with Stage III melanoma were very heterogeneous in terms of their survival probabilities (5-yr overall survival ranged from 70% in patients with Stage IIIA disease to 24% in patients with Stage IIIC disease). Furthermore, in the 2002 system, there was substantial prognostic overlap between Stage II and Stage III. Despite the increased complexity of the 2002 system, the 2 staging systems had similar concordance estimates: 58% for the 1997 staging system compared with 58% (ignoring the subgroups) and 59% (with subgroups) for the 2002 system.

Conclusions: Estimates of stage-specific survival were altered substantially by the changes made in the 2002 AJCC staging system for melanoma, particularly for Stage II. Stage subgroups that were added in the 2002 system resulted in a large diversity of risk within Stage III. This must be taken into account to stratify patients properly for clinical trials. The increased complexity of the 2002 system did not improve its predictive ability over the simpler 1997 system, highlighting the importance of developing individualized risk-prediction models.