The invention provides methods for predicting or determining the response of a mammalian tumor to a chemotherapeutic agent and for treating a mammalian tumor comprising detecting and quantifying the SPARC protein or RNA in a sample isolated from the mammal. The invention further provides kit for predicting the response of a mammalian tumor to a chemotherapeutic agent, comprising a means for the isolation of protein or RNA from the tumor, a SPARC protein or RNA detection and quantification means, control RNAs, and rules for predicting the response of the tumor based on the level of SPARC protein or RNA in tumor.