Parotid cancer: Impact of changes from the 1997 to the 2002 American Joint Committee on Cancer classification on outcome prediction

BACKGROUND. The TNM classification [American Joint Committee on Cancer (AJCC)] of salivary gland cancer was revised again in 2002. In the present study, the outcome prediction of the new TNM system was compared with the old 1997 TNM system in 202 patients with primary parotid cancer. METHODS. All patients treated from 1986 to 2006 were reclassified in both TNM systems. Disease-free survival (DFS) rates were calculated. The prognostic validity of both the TNM system and other factors were analyzed univariately (log-rank test) and multivariately (Cox regression). RESULTS. AJCC TNM stage changes from 1997 to 2002 altered the disease staging in 35% of the patients. Concerning DFS, the new TNM 2002 staging allowed significantly better separation of stage III, but not of stage I versus stage II. The TNM 2002 staging was the most powerful predictor for DFS according to multivariate analysis. The 1997 system showed no independent significance. The subclassification of the new stage IV was not satisfactory; no clear distinction of IVA versus III, and IVA versus PVB was possible. CONCLUSIONS. The TNM 2002 staging is more valid than the 1997 system, but a significant problem was observed in separating stage I from stage II, and within the stage IV subgroups.