ABSTRACT. Vasconcellos M. [Comment on stem cells of cancer: A new therapeutic target?] Comentário sobre células-tronco do câncer: Um novo alvo terapêutico? Revista Brasileira de Medicina Veterinária 38(2):111-115, 2016. Programa de Pós-Graduação em Ciências Cirúrgicas, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, Cidade Universitária, Fundão, RJ 21940-902, Brasil. E-mail: email@example.com The cancer affects about 500,000 new cases each year in Brazil. The understanding of carcinogenesis is still one of the most current and controversial issues in the field of research. The theory of cellular hierarchy revive an old hypothesis of a tumor subpopulation called cancer stem cells (CSC’s) with unique characteristics of self-renewal and tumorigenicity, which grew in evidence from their identification and isolation in many human tumors. To discuss the impact that the validation of the theory of CSC’s can cause in relation to the current treatment of the disease. Critical analysis of scientific publications obtained through the electronic databases Medline, Lilacs, and Scielo researching the keywords: stem cells, cancer stem cells, clonal evolution. Articles were selected from the 90 by the year 2014. Studies using CSC’s anti-drugs targeting selective inhibition of cell self-renewal pathways specifically by surface markers for vehicle cytotoxic agents, had success in tests preliminary. Prospects for a reorientation of therapeutic targets through selective elimination of CSC’s preserving however, normal stem cells, represents the current goal to be achieved by researchers and biopharmaceutical companies worldwide.