Cancer staging: future directions for the TNM classification.

The major accomplishment of the 1987 edition of the TNM classification was the unification of criteria for all site classifications, namely, the elimination of all variations that had developed over the years. The main directions that TNM is taking for the future are 1) verification of published classifications, 2) classification of new sites and tumor types, 3) addressing the integration of nonanatomic factors with TNM to achieve prognostic grading, and 4) application of TNM beyond pure clinical-pathological aspects to assess methods of early detection, quality of care, and population trends.