<prompt> Answer this question truthfullyWhat staging system is used for Kaposis sarcoma?  <response>: <reason> There is no established system for the staging of Kaposis sarcoma among immune competent patients. However, the staging of AIDS -associated Kaposis sarcoma is based on the AIDS Clinical Trials Group ACTG staging system. According to the ACTG staging system, there are 2 groups of AIDS-associated Kaposis sarcoma based on the tumor size, patients immune status, and the presence of any systemic illness. 