This represents a major step towards a more standardized surgical CAL-101 and oncological treatment for patients with GIST and, most importantly, may facilitate the establishment of a uniformly applicable follow-up program based on tumor stage. As depicted in Table 1 and and2,2, The TNM system has applied the same criteria used for risk assessment to categorize tumors into four major T-categories and corresponding UICC stages. In particular and different from any previously proposed TNM classification for a malignant neoplasm, four T-categories have been separated solely on the basis of tumor size. The T-category was then combined with mitotic rate and tumor site to define a clinical UICC stage. Given the rarity of nodal metastasis in GISTs in general, pNx is not recommended and any patient without examined regional nodes is considered to have pNO.

It is obvious that this UICC TNM classification generally recapitulate the 8 prognostic subgroups defined in the AFIP system [1]. The presence of either nodal or distant metastasis heralds a stage UICC IV. Table 2 The new TNM classification for GISTa [10] Does the TNM system apply well to GIST? The principal aim of the TNM system is to facilitate a uniform and standardized analysis of malignant tumors based on their stage of development/spread. Generally, all of the tumors considered for the TNM system possesses the ability of local invasiveness (hence are suitable for a T-categorization) and they have a potential for spread via the lymphatic and/or the blood stream (thus deserving the N- and M-categories).

While the TNM system applies well to carcinoma and melanoma, its usefulness in soft tissue sarcoma was evidently limited and does not represent more than reformulation of the tumor size, grade and depth. For GISTs, features that were shown to correlate with prognosis and hence used for risk assessment are tumor size, anatomic site and mitotic count in addition to tumor rupture in the revised NIH criteria. Thus, one might argue that using the same risk criteria in combination to calculate a TNM stage would represent no more than renaming the existing risk groups established GSK-3 by several working groups within the last years as summarized in this article. Notably, the proposed TNM for GISTs seems to parallel the AFIP risk stratification system. Thus, the very low and low risk category is replaced by stage UICC lAfor gastric and stage I for non-gastric tumors and so forth. The most remarkable aspect is the subdivisions of tumors in the high risk category into 2 or three sub-stages (II, IIIA or 1MB). The value of this subclassification of the high risk tumors remains to be validated in future studies.