The Masaoka-Koga Stage

No official stage classification for thymic malignancies has been defined by the Union Internationale Contre le Cancer (UICC) and the American Joint Commission on Cancer (AJCC). The International Thymic Malignancy Interest group (ITMIG) has selected the Masaoka system 1 with the modification proposed by Koga et al 2 as the one that will be used 3 , until a scientifically validated system is defined in the next edition of the international tumor staging manuals in 2017. However, there are details of the Masaoka and Koga classifications that have never been clearly defined. This article addresses this issue in order to achieve consistency in terms from this point forward for ITMIG initiatives. We hope that this standard will be adopted by all researchers, as it will enhance collaboration and definition of a better classification system in the future.