In summary, on the current rise of the gene expression profile studies and their use in the calculation of relapse risk in breast cancer [32], we must not forget that the classification of tumors based in TNM system and IHC including Ki-67 assessment has not lost its prognostic value, keeping greater efficiency and accessibility, and being able to be used with security and lower cost in the clinical routine. The gene discussed is MKI67; the disease is breast carcinoma.